Search

This paper provides an accessible review of the biological and psychological evidence to guide new and experienced researchers in the study of emotional piloerection in humans. A limited number of studies have attempted to examine the physiological and emotional correlates of piloerection in humans. However, no review has attempted to collate this evidence to guide the field as it moves forward. We first discuss the mechanisms and function of non-emotional and emotional piloerection in humans and animals. We discuss the biological foundations of piloerection as a means to understand the similarities and differences between emotional and non-emotional piloerection. We then present a systematic qualitative review (k = 24) in which we examine the physiological correlates of emotional piloerection. The analysis revealed that indices of sympathetic activation are abundant, suggesting emotional piloerection occurs with increased (phasic) skin conductance and heart rate. Measures of parasympathetic activation are lacking and no definite conclusions can be drawn. Additionally, several studies examined self-reported emotional correlates, and these correlates are discussed in light of several possible theoretical explanations for emotional piloerection. Finally, we provide an overview of the methodological possibilities available for the study of piloerection and we highlight some pressing questions researchers may wish to answer in future studies.

During infection, sickness behaviors, such as a hunched stance with piloerection, can facilitate host resistance by supporting the generation and maintenance of fever. Fever, in turn, is mediated by hypothalamic neuroimmune signaling. Sickness behaviors, however, can also be influenced by social stimuli. In the present study, guinea pig pups were injected with lipopolysaccharide to simulate a bacterial infection and then exposed to a novel, threatening environment while either with their mother or alone. We found the presence of the mother suppressed sickness behavior, but enhanced fever, and had no measureable effect on gene expression of hypothalamic mediators of fever. This 3-way dissociation induced by the mother’s presence is interpreted in terms of the differential adaptive consequences of behavioral and febrile responses for pups in this situation. The results contribute to a growing literature linking immunological and social processes.

Female urine-induced male mice ultrasonic vocalizations (FiUSV) are ultrasonic vocalizations produced by adult male mice after presentation of adult female urine, whereas intruder-induced ultrasonic vocalizations (IiUSV) are produced by resident adult female mice when interacting with an intruder female mouse. These affiliative behaviors may be reduced when mice have decreased wellbeing or are in pain and distress. To determine whether FiUSV and IiUSV can be used as proxy indicators of animal wellbeing, we assessed FiUSV produced by male C57BL/6J mice in response to female urine and IiUSV produced by female C57BL/6J mice in response to a female intruder at baseline and 1 and 3 h after administration of a sublethal dose of LPS (6 or 12.5 mg/kg IP) or an equal volume of saline. Behavior was assessed by evaluating orbital tightness, posture, and piloerection immediately after USV collection. We hypothesized that LPS-injected mice would have a decreased inclination to mate or to interact with same-sex conspecifics and therefore would produce fewer USV. At baseline, 32 of 33 male mice produced FiUSV (149 ± 127 USV in 2 min), whereas all 36 female mice produced IiUSV (370 ± 156 USV in 2 min). Saline-injected mice showed no change from baseline at the 1- and 3-h time points, whereas LPS-injected mice demonstrated significantly fewer USV than baseline, producing no USV at both 1 and 3 h. According to orbital tightness, posture, and piloerection, LPS-injected mice showed signs of poor wellbeing at 3 h but not 1 h. These findings indicate that FiUSV and IiUSV can be used as proxy indicators of animal wellbeing associated with acute inflammation in mice and can be detected before the onset of clinical signs.

Piloerection (goosebumps) requires concerted actions of the hair follicle, the arrector pili muscle (APM), and the sympathetic nerve, providing a model to study interactions across epithelium, mesenchyme, and nerves. Here, we show that APMs and sympathetic nerves form a dual-component niche to modulate hair follicle stem cell (HFSC) activity. Sympathetic nerves form synapse-like structures with HFSCs and regulate HFSCs through norepinephrine, whereas APMs maintain sympathetic innervation to HFSCs. Without norepinephrine signaling, HFSCs enter deep quiescence by down-regulating the cell cycle and metabolism while up-regulating quiescence regulators Foxp1 and Fgf18. During development, HFSC progeny secretes Sonic Hedgehog (SHH) to direct the formation of this APM-sympathetic nerve niche, which in turn controls hair follicle regeneration in adults. Our results reveal a reciprocal interdependence between a regenerative tissue and its niche at different stages and demonstrate sympathetic nerves can modulate stem cells through synapse-like connections and neurotransmitters to couple tissue production with demands.

Measuring body surface temperature changes with infrared thermography has recently been put forward as a non-invasive alternative measure of physiological correlates of emotional reactions. In particular, the nasal region seems to be highly sensitive to emotional reactions. Several studies suggest that nasal temperature is negatively correlated with the level of arousal in humans and other primates, but some studies provide inconsistent results. Our goal was to establish the use of infrared thermography to quantify emotional reactions in common marmosets (Callithrix jacchus), with a focus on the nasal region. To do so we exposed 17 common marmosets to a set of positive, negative and control stimuli (positive: preferred food, playback of food calls; negative: playback of aggressive vocalizations, teasing; control: no stimulus). We compared nasal temperature before and after the stimuli and expected that highly aroused emotional states would lead to a drop in nasal temperature. To validate the thermography measure, we coded piloerection of the tail as an independent measure of arousal and expected a negative correlation between the two measures. Finally, we coded physical activity to exclude its potential confounding impact on nasal temperature. Our results show that all predictions were met: the animals showed a strong decrease in nasal temperature after the presentation of negative arousing stimuli (teasing, playback of aggressive vocalizations). Furthermore, these changes in nasal temperature were correlated with piloerection of the tail and could not be explained by changes in physical activity. In the positive and the control conditions, we found systematic sex differences: in males, the preferred food, the playbacks of food calls, as well as the control stimulus led to an increase in nasal temperature, whereas in females the temperature remained stable (preferred food, control) or decreased (playback of food calls). Based on naturalistic observations that document higher food motivation and competition among female marmosets, as well as stronger reactions to separation from group members in male marmosets, these sex differences corroborate a negative correlation between arousal and nasal temperature. Overall, our results support that measuring nasal temperature by infrared thermography is a promising method to quantify emotional arousal in common marmosets in a fully non-invasive and highly objective way.

We determined the receptor subtypes of α1-adrenoceptor, which is involved in autonomic functions induced by methamphetamine (METH) in rats. An intraperitoneal injection of METH provoked the autonomic responses piloerection, eyelid retraction, and ejaculation. Pretreatment with prazosin, a nonselective α1-adrenoceptor antagonist, completely abolished the above METH-induced responses. Prazosin also provoked eyelid ptosis in saline controls. The effects of prazosin were mimicked only by a selective α1A-adrenoceptor antagonist, silodosin, not by selective α1B or α1D antagonists. These results suggest that α1A-adrenoceptor participates in the regulation of piloerection, palpebral fissure width, and ejaculation in rats.

The development of myoclonic activity as a toxic effect of morphine application into the intrathecal space in rats is described. This syndrome resembled the human syndrome of action myoclonus by its spontaneous onset and its augmentation by initiation of movement or by an acoustic stimulus. It was not reversed or prevented by naloxone. This effect of morphine was associated with an increase in serotonergic activity in the spinal cord and was reduced by pretreatment with parachlorophenylalanine in doses which reduced spinal 5-HT by approximately 60%. The dose which produced this syndrome was about ten times higher than the analgesic dose applied by the same route. Other commonly used opiates such as: methadone (0.5-2 mg/kg), pethidine (2-10 mg/kg), fentanyl (2-10 micrograms/kg) and ketamine (2-10 mg/kg) did not produce myoclonic-like activity, but methadone and pethidine at the highest doses caused respiratory arrest. Fentanyl appeared to be the safest of the drugs tested since a relatively high dose, administered into the intrathecal space did not cause any side effects, while morphine was least safe of the five drugs since it produced myoclonic activity in addition to the widely documented respiratory depression. We suggest that the production of the myoclonic activity is mediated by spinal serotonergic systems.

Responding for rewarding brain stimulation has been used to track hedonic status in animals. In addition to neurochemical alterations, stimulation of the lateral hypothalamus or ventral tegmentum has been shown to influence immunological processes, including elevation of peripheral natural killer cell activity. In the present study, we examined whether ventral tegmental area (VTA) stimulation or environmental enrichment altered the severity of lipopolysaccharide (LPS)-induced sickness behaviors and the provocation of cytokine expression induced by the endotoxin. Accordingly, rats received either trials of brain stimulation reward or exposure to an enriched environment and subsequently challenged with 150 ug/kg i.p. of LPS. Groups receiving LPS and saline injections without further manipulation were also included. Using the real-time RT-PCR and a multiplex bead assay, mRNA and protein levels for several cytokines and their receptors were determined to evaluate how these may vary as a consequence of reward. Both brain stimulation and environmental enrichment similarly diminished sickness behaviors associated with the endotoxin. Receptor gene levels were generally stable across groups. Levels of IL-6 within the VTA were increased in the group receiving LPS challenge alone and environmental enrichment was associated with modestly reduced IL-6 levels within this brain region. Taken together, these data suggest that rewarding brain stimulation and environmental enrichment buffer against malaise provoked by endotoxin challenge. Moreover, IL-6 expression within the VTA may influence the development of sickness behavior following inflammatory stimuli.

Interferon-alpha (IFN-alpha) is a cytokine used as a first line of defense against diseases such as cancer and hepatitis C. However, reports indicate that its effectiveness as a treatment is countered by central nervous system (CNS) disruptions in patients. Our work explored the possibility that it may also cause long-term behavioral disruptions by chronicling the behavioral and physiological disturbances associated with a single injection of vehicle, 10, 100, or 1,000 units of IFN-alpha in male Sprague-Dawley rats (n = 5/dose). Following 1 day of locomotor baseline collection, we monitored sickness behaviors (ptosis, piloerection, lethargy, and sleep), food and water intake, body weight, temperature, and motor activity. Observations were recorded 4 days prior to and 4 days following the IFN-alpha injection. Temperature and sickness behaviors were recorded three times daily at 9:00, 15:00, and 21:00 h, and all other indices, once daily. On the injection day, temperature values were highest in the animals receiving the 10-unit IFN-alpha dose 15 min and 13 h post-injection. In the case of sickness behaviors, a significant increase was observed in piloerection in all IFN-alpha groups at each time point measured, while the scores of the rats in the vehicle condition remained unchanged between pre- and post-injection days. Analyses of overall sickness behaviors during morning and night observation periods indicated increased scores in all IFN-alpha groups following injection. Cumulatively, these data suggest that a single IFN-alpha exposure may elicit long-term behavioral disruptions and that its consequences should be thoroughly investigated for its use in clinical populations.

We have proposed that passive responses observed following maternal separation in guinea pig pups represent "stress-induced sickness behaviors" mediated by proinflammatory processes. In this study, the anti-inflammatory peptide, alpha-melanocyte stimulating hormone (alpha-MSH) administered intracerebroventricularly, but not intraperitoneally, reduced the passive responses of crouching, eye-closing, and extensive piloerection relative to levels following administration of vehicle. These findings support our hypothesis and are as would be expected if pro-inflammatory processes act centrally to promote the passive behaviors of separated guinea pig pups.

Prepulse inhibition (PPI) refers to the attenuation of startle when a weak prestimulus precedes the startling stimulus. PPI is deficient in several psychiatric illnesses involving poor sensorimotor gating. Previous studies indicate that alpha1 adrenergic receptors regulate PPI, yet the extent to which these effects are mediated by central vs peripheral receptors is unclear. The present studies compared the effects of intracerebroventricular (ICV) vs intraperitoneal (IP) delivery of several alpha1 receptor agonists on PPI. Male Sprague-Dawley rats received either cirazoline (0, 10, 25, 50 microg/5 microl), methoxamine (0, 30, 100 microg/5 microl), or phenylephrine (0, 3, 10, 30 microg/5 microl) ICV immediately before testing. Separate groups received either cirazoline (0, 0.25, 0.50, 0.75 mg/kg), methoxamine (0, 2, 5, 10 mg/kg), or phenylephrine (0, 0.1, 2.0 mg/kg) IP 5 min before testing. PPI, baseline startle responses, and piloerection, an index of autonomic arousal, were measured. Cirazoline disrupted PPI; effective ICV doses were approximately six times lower than effective IP doses. Methoxamine disrupted PPI after ICV infusion but failed to affect PPI with IP doses that were up to 30-fold higher than the effective ICV dose. Phenylephrine disrupted PPI with ICV administration, but did not alter PPI after IP injection of even a 20-fold higher dose. None of the ICV treatments altered baseline startle magnitude, but phenylephrine and methoxamine lowered startle after administration of high systemic doses. Piloerection was induced by cirazoline via either route of administration, and by IP methoxamine and phenylephrine, but not by ICV infusion of methoxamine or phenylephrine. These findings indicate that alpha1 receptor-mediated PPI disruption occurs exclusively through stimulation of central receptors and is dissociable from alterations in baseline startle or autonomic effects.

We recently reported that the centromedian–parafascicular thalamic complex (CM–Pf) degenerates in Parkinson's disease and progressive supranuclear palsy. The contribution of such thalamic pathology to disease symptoms has not yet been established. The present study therefore investigated the behavioural impact of lesioning the corresponding thalamic region (termed Pf) on a range of behaviours present in rodents. There were four surgical groups: (1) sham medial forebrain bundle (mfb) + sham Pf, (2) 6-OHDA mfb lesion + sham Pf, (3) sham mfb + NMDA Pf lesion, (4) 6-OHDA + NMDA Pf lesions. Posture, sensory functions and apomorphine-induced rotational asymmetry were assessed before and after each surgery. Other assessments performed including a timed motivational task, grooming behaviours and piloerection. 6-OHDA lesions induced postural (ipsilateral curling and head position biases), sensorimotor (increased latency to respond to tactile stimulation of the contralateral side when eating or grooming) and rotational abnormalities (contralateral circling after apomorphine). The main effects of combined 6-OHDA + Pf lesions were improved performance in a motivational task (decreased latency to retrieve reward) but worsened piloerection, relative to animals with either 6-OHDA or Pf lesions alone. The thalamic zone common to all lesioned animals involved the posterior Pf. Our data suggests that the posterior CM–Pf may be involved in motivational responses and autonomic dysfunction in parkinsonian disorders.

A combination of medetomidine hydrochloride (medetomidine) and ketamine hydrochloride (ketamine) was evaluated in 16 boma-confined and 19 free-ranging impalas (Aepyceros melampus) to develop a non-opiate immobilisation protocol. In free-ranging impala a dose of 220 +/- 34 microg/kg medetomidine and 4.4 +/- 0.7 mg/kg ketamine combined with 7500 IU of hyaluronidase induced recumbency within 4.5 +/- 1.5 min, with good muscle relaxation, a stable heart rate and blood pH. PaCO2 was maintained within acceptable ranges. The animals were hypoxic with reduced oxygen saturation and low PaO2 in the presence of an elevated respiration rate, therefore methods for respiratory support are indicated. The depth of sedation was adequate for minor manipulations but additional anaesthesia is indicated for painful manipulations. Immobilisation was reversed by 467 +/- 108 microg/kg atipamezole hydrochloride (atipamezole) intramuscularly, but re-sedation was observed several hours later, possibly due to a low atipamezole:medetomidine ratio of 2:1. Therefore, this immobilisation and reversal protocol would subject impalas to possible predation or conspecific aggression following reversal if they were released into the wild. If the protocol is used on free-ranging impala, an atipamezole:medetomidine ratio of 5:1 should probably be used to prevent re-sedation.

This study was aimed at investigating the coping style of mice subjected to a subchronic unpredictable mild stress procedure and its relationship to initial emotional reactivity. Two inbred strains of mice, the BALB/c ByJ and the C57BL/6 J, known to exhibit distinct emotionality, have been used. They were first observed in the elevated plus-maze and the free exploratory paradigm, each provides a separation of the population in high and low emotional mice. Half of the mice of each strain were then confronted to a 2-week subchronic unpredictable mild stress and tested for their responses in different behavioural situations (consumption of a palatable food, physical state, grooming behaviours and reactivity to a conflict situation). Mice were also tested in the light/dark procedure to assess the effect of the subchronic stress on emotional reactivity. First, a relationship between initial emotional reactivity in the elevated plus-maze and behavioural coping style in response to stress was found, high emotional mice (i.e., BALB mice) displaying inhibited behaviours and less emotional mice (i.e., BL/6 mice) exhibiting few behavioural changes. Furthermore, emotional reactivity was increased in stressed mice compared with nonstressed ones.

Some rodent species show rhythmic bouts of vibrissal protractions and retractions, referred to as whisking, that are among the fastest movements performed by mammals. To better understand the muscular basis of whisking, we compared (1) whisker movements of two whisking species (mouse, rat) and a non-whisking species (guinea pig), (2) the muscle fiber composition of intrinsic whisker muscles of whisking and a non-whisking species, and (3) the muscle fiber composition of intrinsic whisker muscles and of selected skeletal muscles. Using high-speed videography, we found that mice, rats, and guinea pigs can generate fast and large-amplitude whisker movements. Guinea pigs do not show bouts of fast, strictly rhythmic whisker movements, and the average speed of their whisker movements is much lower than in mice and rats. Analysis of mRNA expression of myosin heavy chain isoforms, myofibrillar ATPase staining, and antibody labeling indicate that in all three species intrinsic whisker muscles are composed predominantly of type 2B muscle fibers. Intrinsic whisker muscles of mice consisted of type 2B (> or =90%) and type 2D fibers. In rats we observed, in addition to type 2B/2D fibers, approximately 10% of slow type 1 fibers, and in guinea pigs we observed approximately 3% of slow type 1 fibers and 20% of type 2A fibers. Type 2B fibers have high levels of anaerobic glycolytic enzymes providing a rapid source of ATP and high maximum velocity of contraction but are less fatigue resistant than other muscle fiber types. The high percentage of type 2B fibers distinguishes the intrinsic whisker musculature from skeletal muscles and may have evolved for fast scanning of the sensory environment.

When guinea pig pups are isolated in a novel environment, they show an initial active phase of behavioral responsiveness characterized by vocalizations and locomotor activity. One earlier study found that after about an hour, pups began to exhibit a second, passive stage of responsiveness marked by a crouched stance, eye-closing, and extensive piloerection. The present experiments tested the hypothesis that the responses during the second, passive stage result from the isolation experience activating pathways underlying the acute phase response, i.e., that behaviors of the second stage represent "stress-induced sickness behaviors". We found the following: (1) the passive stage did not emerge if pups remained with the mother during exposure to a novel cage; (2) injection of lipopolysaccharide, which induces an acute phase response, also led pups to exhibit crouching, eye-closing, and piloerection; and, (3) isolation in the novel cage produced a rise in rectal temperature, but did not affect peripheral or central levels of interleukin-1beta (IL-1beta)-immunoreactivity. Overall, these results are consistent with the notion that stress-induced sickness behaviors can account for some of the behaviors of isolated guinea pig pups, though if this is the case, cytokines other than IL-1beta appear to be involved.

Laetia suaveolens, known as “casinga-cheirosa”, crude extract EB719 has previously shown cytotoxic activity against prostate cancer and squamous cell carcinoma. For the first time, seven molecules were isolated from its apolar—α-tocopherol (1) and sitosterol (2)—and polar—3-O-caffeoylquinic acid (3), 4-O-caffeoylquinic acid (4), 5-O-feruloylquinic acid (5), hyperoside (6), and isoquercitrin (7)—fractions. Acute toxicity was determined in a two-stage experiment: (1) a reduced number of Balb-c male mice received 5000 mg/kg of EB719 to allow evaluation of general activity and other 27 parameters, plus death, up to the establishment of non-lethal dose (NLD), as well as lethal dose 50% (LD50); (2) NLD was administered and diazepam introduced as reference drug. EB719 showed LD50 = 178.0 mg/kg, and NLD 156.3 mg/kg. In stage one EB719 did not influence general activity, but provoked impairment in grasp reflexes, tail squeeze and breathing; piloerection and cyanosis were increased. In stage two, alterations occurred in auricular reflex, piloerection and breathing after diazepam administration, but not in response to EB719. Intestinal hemorrhage caused by local bleeding was observed after necropsy, and may be the main cause of animals’ death other than a systemic effect of the extract. Although the isolated compounds are biologically and pharmacologically active in both men and animal systems, it is premature to relate their occurrence in EB719 to the observed intestine hemorrhage in mice.

I first saw the patient, a 4.5 kg domestic shorthair cat, when it was presented for its annual vaccinations at 3 years old. It had sustained a severe crush injury to the right hind leg in a road traffic accident 2 years earlier, necessitating amputation. On examination, the cat had an area of alopecia along the dorsum, extending from the thoracolumbar junction to the pelvis, caused by excessive self-grooming. Sometimes the cat appeared to attack its back. When I touched the lumbar area a twitch response and muscle spasm were elicited, and dorsal skin rippling and piloerection were present. The cat began to growl with stronger palpation to the area. I found significant discomfort on palpation of the longissimus dorsi muscles, especially in the thoracolumbar area with multiple myofascial trigger points (MTrPs), often seen in animals after limb amputation owing to the alteration in gait. The owners informed me that the cat had become less social since the onset of the signs and occasionally twitched whilst being stroked, jumped off the owner and ran away. Frantic licking behaviour often followed. Trichograms and skin scrapes disclosed no underlying dermatological problems and there were no lesions visible on the skin in the alopecic areas. No other abnormalities were found on clinical examination. Feline hyperaesthesia syndrome was considered to be the most likely diagnosis, possibly caused by phantom pain, as the symptoms had …

A method of measuring confrontation-induced behavioural changes in common marmosets (Callithrix jacchus) together with automated monitoring of locomotor activity has been developed as a possible model of anxiety. Recording both affiliative and agonistic behaviours between male/female pairs of marmosets and using diazepam as a reference drug, it has been possible to define a profile of behavioural changes which could be regarded as representing an anxiolytic response. Unfamiliar male/female pairs of marmosets were brought into close (non-contact) proximity in a controlled environment, in which their locomotor activity was recorded automatically. Simultaneously, their interactive behaviour was assessed by an independent observer via closed-circuit television. The following behaviours were analysed: aggressive postures, allogrooming, scratching, anxiety-related behaviours, social contact and self-grooming. Administration of diazepam at 1 and 3.5 mg/kg PO induced a significant (compared to control) reduction in scratching, aggressive behaviours, anxiety-related behaviours and an increase in allogrooming without affecting locomotor activity during confrontation. Differing responses dependent on gender were not found, nor did gender influence the effect of treatment on behaviour. Habituation to repeated confrontation did not occur. The results from this study demonstrate that this method can be used to measure anxiolytic activity in an objective manner.

The insulating properties of the primate integument are influenced by many factors, including piloerection, which raises the hair and insulates the body by creating motionless air near the skin's surface. The involuntary muscles that control piloerection, the musculi arrectores pilorum (MAP), are mostly absent except on the tail in most strepsirhines, and are entirely absent in tarsiers and some lorisids. The absence of piloerection and the reduced effectiveness of pilary insulation in preventing heat loss affected the evolution of behavior and metabolic thermoregulation in these animals. In lemurs, this situation contributed to the use of positional and social behaviors such as sunning and huddling that help maintain thermal homeostasis during day-night and seasonal temperature cycles. It also contributed in many lemurs and lorises to the evolution of a wide variety of activity patterns and energy-conserving metabolic patterns such as cathemerality, daily torpor, and hibernation. The absence of functional MAP in strepsirhines and tarsiers implies the absence of effective piloerection in early primates, and the reacquisition of whole-body MAP in ancestral anthropoids prior to the separation of platyrrhine and catarrhine lineages. © 2013 S. Karger AG, Basel.

Guinea pig pups vocalized more and were more active during a 60-min period of isolation in a novel environment when injected SC with 50 micrograms of the corticotropin-releasing factor (CRF) antagonist, [D-Phe]CRF12-41, than when injected with saline vehicle only. More pups exhibited eye closing and extensive piloerection when injected with saline than when injected with the antagonist. Plasma levels of cortisol following testing were not affected by the injections. These results support the hypothesis that endogenous CRF contributes to the normal decline in vocalizing and locomotor activity that guinea pig pups show with continued isolation. The results also suggest that endogenous CRF plays a role in the eye closing and piloerection of isolated pups. The finding that the dose of the antagonist used altered behavior, yet was not sufficient to lower plasma cortisol levels, supports earlier evidence that the observed effects of CRF are not due to the actions of ACTH or glucocorticoids.

Mono-n-benzyl phthalate (MBeP), one of the major metabolites of the plasticizer n-butyl benzyl phthalate, was evaluated for developmental toxicity in Wistar rats. Rats were given MBeP by gastric intubation at 0, 250, 313, 375, 438 or 500 mg/kg from day 7 through day 15 of pregnancy. Significant decreases in the maternal body weight gains and food consumption during administration period were observed at 313 mg/kg and above and at 250 mg/kg and above, respectively. Significant increase in the incidence of postimplantation loss per litter was found at 438 and 500 mg/kg. The incidences of fetuses with external malformations at 438 mg/kg, of fetuses with skeletal malformations at 313 mg/kg and above and of fetuses with internal malformations at 375 mg/kg and above were higher than those in the control group. Defects in the cervical and thoracic vertebrae, ribs and kidney were frequently observed.

The autologous transplantation of hair follicles that have been separated into single follicular units is an accepted treatment for androgenetic alopecia. Recent studies demonstrate that the multiple stem cell populations and surrounding cutaneous tissues coordinately regulate the hair follicle functions and skin homeostasis. Therefore, the critical issues for consideration regarding functional hair restoration therapy are reproduction the correct connectivity and cooperation with host cutaneous tissues, including the arrector pili muscle (APM) and nerve system. We report successful establishment of mouse single follicular transplantation model and autonomous restoration of transplanted hair follicle piloerection in mouse skin. Transplanted hair follicles were responsive to the neurotransmitter acetylcholine and formed proper connections with surrounding host tissues such as APM and nerve fibers, which in turn connect with not only the hair follicle bulge region but also the APM. These results demonstrate that the piloerection ability of transplanted hair follicles can be estimated quantitatively. This study makes a substantial contribution towards the development of transplantation therapy that will facilitate future functional regeneration therapy for skin and skin appendages.

This study was designed to characterize the cocaine-induced rausch or hyperarousal syndrome in rhesus monkeys. This syndrome mimics the stage observed in human abusers bingeing on cocaine and is considered crucial in the progression from recreational use to compulsive abuse. However, little research has focused on this important aspect of cocaine use. Cocaine was administered i.v. at doses of 0.0, 0.5, 1.0 and 2.0 mg/kg. Plasma concentrations were determined by gas chromatograph mass spectrometry (GC/MS) using deuterated internal standards d3 cocaine and d3 benzoylecgonine (BE). Mean plasma concentrations of cocaine, were on samples collected 1 min after infusion, 46 +/- 31, 88 +/- 15 and 275 +/- 116 mg/microliters in the 0.5, 1.0 and 2.0 mg/kg dose groups, respectively. There were no detectable concentrations of BE in any of the specimens nor was cocaine detected in the saline controls. Analysis of the behavioural data revealed that the 0.5 and 1.0 mg/kg results were intermediate between the results obtained at doses of 0.0 and 2.0 mg/kg and that the 1.0 mg/kg dose produced a higher response than the 0.5 mg/kg dose up to the 12 min. Regarding individual behavioural signs, those designated escape attempts, checking, feinting, restlessness, searching, vocalizing, chewing, crouching and wide-eyed were noted most frequently. The results showed dose-response relationships for both plasma concentrations of cocaine and for the total number of overt behavioural signs. The plasma concentrations were in the range reported for human cocaine abusers.

The purpose of the present study was to investigate the role of the locus coeruleus in the development of opiate dependence. Two groups of rats each were subjected to either a electrolytic lesion of the locus coeruleus or a sham lesion. All animals were implanted with an intracerebroventricular (i.c.v.) cannula, and made physically dependent by subcutaneous insertion of two 75-mg morphine (base) pellets. Abstinence was precipitated by i.c.v. administration of methylnaloxonium (31-1,000 ng) 72 h after pellet implantation. Methylnaloxonium administered intracerebroventricularly induced a withdrawal syndrome characterized by the appearance of teeth chattering, mastication, rearing, wet dog shakes, jumping, piloerection, hyperactivity, ptosis and eye twitch. Withdrawal observed in the electrolytic lesion groups was less severe than in sham group. The presence of mastication, rearing, piloerection, hyperactivity, ptosis and eye twitch was significantly lower. These results support the hypothesis that the locus coeruleus has an important role in the expression of the physical signs of opiate dependence.

The deformation of rat skin in response to cooling and stimulation of nerve fibers innervating the muscles piloerectors and vasoconstrictors has been studied by optical coherent microscopy. It has been found that the deformation of the skin on cooling occurs due to the contraction of bundles of collagen fibers rather than smooth muscles of vessels and piloerectors.

Triple-labelling immunofluorescence and retrograde axonal tracing with fluorescent dyes have been combined to identify and characterize the neuropeptide content of vasoconstrictor, vasodilator and pilomotor neurons in the lumbar sympathetic ganglia of guinea-pigs. Postganglionic noradrenergic pilomotor neurons lacked immunoreactivity to neuropeptide Y and comprised up to about 30% of postganglionic neurons. Most post-ganglionic noradrenergic neurons that contained neuropeptide Y immunoreactivity were likely to be vasoconstrictor neurons, although some noradrenergic neurons containing neuropeptide Y projected to pelvic viscera. Vasoconstrictor neurons comprised up to about 60% of postganglionic neurons. About 15% of postganglionic neurons were non-noradrenergic and contained immunoreactivity to vasoactive intestinal peptide, neuropeptide Y and dynorphin. They mostly innervated blood vessels supplying skeletal muscles and were likely to be vasodilator neurons. Endings of presumed preganglionic neurons containing immunoreactivity to substance P were exclusively associated with vasodilator neurons. Conversely, presumed preganglionic endings containing immunoreactivity to calcitonin gene-related peptide were exclusively associated with vasoconstrictor neurons, although not all vasoconstrictor neurons had such endings associated with them. Presumed preganglionic terminals containing immunoreactivity to enkephalin were associated with some postganglionic neurons in each functional class. These results show that preganglionic and postganglionic sympathetic neurons lying in different functional pathways can be distinguished by their neuropeptide content as well as their projections. The identification of neurochemically distinct functional pathways begins to explain how the sympathetic nervous system is organized to allow the precise control of discrete target tissues.

Percutaneous nicotine administration induces predominant sudorific and rubiform responses in the skin which may be accompanied by subtle piloerection, hyperalgesia and pruritus (although these signs are not overtly manifest). These dermal responses are complex and mechanisms have been proposed for the direct nicotine-stimulation of sweat glands, piloerection and vasoconstriction. These reactions are accompanied by secondary activation and release of vasodilator peptides which produce a predominating vasodilator tone following topical administration, this response masking the direct axon reflex-mediated vasoconstriction.

Most animals used in research are rodents, mainly mice because of their predominance in genetics and molecular biology. This article attempts to provide an introduction to mice and rats: health considerations (of the experimenter); choice of species, age, strain and sex; housing and environmental enrichment; and animal identification, handling and dosing. These considerations apply to animal work in general; the rest of the article focuses on the preliminary aspects of behavioral testing, including a protocol for an open field test. This procedure is traditionally associated with activity measurements, and although automated versions are readily available these days, the latter are expensive and may be unavailable in many non-behavioral departments. Moreover, particularly when testing novel genetically modified animals or pharmacological agents, there is no substitute for direct visual observation to detect abnormal signs in the animals: for example, ptosis, piloerection, tremor, ataxia or exophthalmos. The open field test can be adapted in several ways: to assess general behavior and activity (similar to a primary screen in the pharmaceutical industry) or to measure memory (habituation) or anxiety.

Levetiracetam (LEV, [S]-alpha-ethyl-2-oxo-1-pyrrolidine acetamide) is a new antiepileptic that has been used as adjunctive therapy to treat patients with intractable epilepsy. Systemic administration of levetiracetam (2.5-30 mg/kg, intraperitoneally (i.p.)) was able to produce a dose-dependent decrease in DBA/2 audiogenic seizure severity score. In combination with conventional antiepileptic drugs, levetiracetam, 5mg/kg, i.p., which per se did not significantly affect the occurrence of audiogenic seizures in DBA/2 mice, potentiated the anticonvulsant activity of some antiepileptic drugs studied against sound-induced seizures in DBA/2 mice. The degree of potentiation induced by levetiracetam was greater, approximately twice, for carbamazepine, diazepam, felbamate, topiramate, gabapentin, and valproate, less for lamotrigine, phenobarbital and phenytoin. This increase was associated with a comparable impairment in motor activity; however, the therapeutic index of combined treatment of antiepileptic drugs with levetiracetam was more favourable than the combination with saline with the exception of lamotrigine, phenytoin and phenobarbital. Since levetiracetam did not significantly influence the total and free plasma and the brain levels of antiepileptics studied. In addition, levetiracetam did not significantly affect the hypothermic effects of the anticonvulsants tested. In conclusion, levetiracetam showed an additive anticonvulsant effect when administered in combination with some classical anticonvulsants, most notably carbamazepine, diazepam, felbamate, gabapentin, topiramate and valproate, implicating a possible therapeutic relevance of such drug combinations.

The present work was designed to establish a novel animal model for motion sickness (MS) in rodents and to evaluate the effects of a combination of scopolamine and modafinil on MS with this novel method. It was found that the rats and mice presented several symptoms induced by rotation such as, piloerection, tremble, urinal and fecal incontinence. As the rats and mice are lack of emesis response to rotation, we used a score based on abovementioned symptoms as an index for the severity of MS in rodents. MS index was determined in 260 mice with this novel method. It was found that the distribution of MS index was normal (W=0.99; P=0.23. P>0.05 considered values' normal distribution). The effects of scopolamine on MS were studied in mice and rats. It was found that scopolamine significantly decreased MS index at the dose of 0.3 mg/kg in mice and 1.0 mg/kg in rats. Finally, the effects of a combination of scopolamine and modafinil were observed with this novel method in rats. It was found that the efficacy of the combination (5.0+5.0 mg/kg) was greater than the single drugs (10 mg/kg). Even the smallest dose of the combination (0.5+0.5 mg/kg) had a similar effect to large dose of scopolamine or modafinile when they were used alone. In conclusion, this animal model is suitable for MS study in rats and mice and the combination of scopolamine and modafinil might be a new method to treat or prevent MS.

The purpose the present study was to determine if tolerance is developed to all behavioural effects produced by a single high dose of chlorpyrifos (CPF). For this, the study was divided in two phases; in the first phase, we studied the time course of the effects produced by treatment with a high dose of CPF (250 mg/kg s.c.) on rat locomotor activity and anxiety behaviours recorded on an open-field, as well as on AChE inhibition. Results showed that CPF produced a maximum inhibition of AChE (72% of inhibition) 2 days after its administration, exhibiting a partial recovery of its activity by day 30 (55% of inhibition). On locomotor activity CPF produced a biphasic effect; a reduction only on day 2, and an increase on day 30. An anxiolytic-like effect was only observed within 2 and 5 days after CPF treatment. These results indicate that the tolerance has been developed to the behavioural effects produced by s.c. administration of CPF, but with a different time course. In the second phase, since disturbances in cholinergic system might trigger dopaminergic disfunctions, we tested the locomotor activity following challenge with amphetamine (1 mg/kg i.p.) at 11 and 30 days after CPF treatment. Data obtained showed that amphetamine produced an increase in total distances and rearing in vehicle and CPF groups on days 11 and 30. However, CPF group exhibited lower increase relative to vehicle group in both days. This effect is independent of the percentage of AChE inhibition and therefore, of change in the cholinergic system. Data are discussed under the light of the adaptative mechanisms underlying the recovery of the cholinergic overstimulation after s.c. exposure to high doses of CPF.

A previous study found that intracerebroventricular (ICV) infusion of 25 microg of alpha-MSH reduced the passive responses (crouched stance, eye-closing, piloerection) of guinea pig pups during a 3-h isolation in a novel environment. Because alpha-MSH has broad anti-inflammatory properties, the results suggested that proinflammatory factors play a role in mediating the behavior of isolated infants. The present study further investigated this possibility. In Experiment 1, injection of lipopolysacchride (LPS) increased the number of 60-s intervals in which pups expressed the same three responses during a 1-h test, and ICV infusion of alpha-MSH significantly reduced the effect of LPS on crouching and piloerection. In Experiment 2, the prostaglandin synthesis inhibitor indomethacin (10 mg/kg) reduced the number of 60-s intervals in which pups exhibited both crouching and the full suite of passive responses during a 3-h isolation in a novel environment. Together these results provide further support for the hypothesis that the passive behaviors exhibited during prolonged isolation are "stress-induced sickness behaviors" mediated by proinflammatory factors.

Swiss Webster pups were fathered by sires given either an acute dose of alcohol (alcohol-sired) or saline (saline-sired) 12-24 h before mating. The same sires were used to father both groups of pups. Alcohol-sired pups were significantly lighter at birth and for the following three weeks than were saline-sired pups. Significantly more pups were fathered by saline-exposed sires, and dams carrying those pups had significantly longer gestations than those carrying pups of alcohol-using sires. More runts were born to the alcohol-sired group, and more pups in that group died over the next three weeks than in the saline-sired group. Significantly more pups in the saline-sired group achieved such developmental milestones as surface righting, clinging, the tail-pull reflex, rotation, linear movement and climbing an inclined surface earlier than did alcohol-sired pups. As adults, animals from the alcohol-sired group showed significantly less risk assessment behavior and longer latencies to such behaviors as stretched attention, flatback, freezing and defensive burying than did the saline-sired animals. Alcohol-sired animals contacted the stimulus object in the risk assessment test significantly sooner and more often than did the saline-sired group. In tests of aggression, alcohol-sired male offspring showed more frequent aggressive behaviors such as on-top, lateral attacks and jump-attacks, and significantly fewer defensive/fearful behaviors such as piloerection, tail rattling and jump-escape. This pattern of results suggests that exposure of the sire to one acute dose of alcohol before insemination caused some early developmental delays and that alcohol-sired animals are less fearful and more aggressive as adults than saline-sired animals.

Isoflavone supplements are nowadays widely used as alternative for hormone replacement therapy. However, the safety remains unanswered. This study attempted to investigate the effect of Pueraria lobata root decoction (PLRD), an isoflavone-rich herb, on the pharmacokinetics of methotrexate (MTX), a bicarboxylate antimetabolite with narrow therapeutic window. Rats were orally and intravenously given methotrexate alone and coadministered with PLRD. Blood samples were withdrawn via cardiopuncture at specific time points after drug administration. Serum methotrexate concentrations were assayed by specific monoclonal fluorescence polarization immunoassay method. Pharmacokinetic parameters were calculated using noncompartment model of WINNONLIN for both oral and intravenous data of MTX. Our results showed that coadministration of 4.0 g/kg and 2.0 g/kg of PLRD significantly increased the AUC(0-t) by 207.8% and 127.9%, prolonged the mean residence time (MRT) by 237.8 and 155.2%, respectively, finally resulted in surprisingly high mortalities of 57.1% and 14.3% in rats. When MTX was given intravenously, the coadministration of PLRD at 4.0 g/kg significantly increased the half-life by 53.9% and decreased the clearance by 47.9%. In conclusion, the coadministration of PLRD significantly decreased the elimination and resulted in markedly increased exposure of MTX in rats.

The aim of the present study was to examine possible long-term effects of the anabolic androgenic steroid (AAS), nandrolone decanoate (ND), on dominance in a provoking and competitive situation in sexually matured male rats. The experimental group (n=10) received daily injections of ND [15 mg/kg in a volume of 1 ml/kg subcutaneous (s.c.) injection for 14 days]. During the corresponding period, the controls (n=10) were given daily injections of an oil vehicle (1 ml/kg s.c.). All animals were tested in a competitive situation at four occasions after the end of the treatment period (week 5, 8, 11 and 14). Water-deprived pairs of rats, consisting of one ND-treated rat and one control, had to compete for access to water. The results showed that the ND-treated rats approached the water spout significantly more often compared to the controls. During the competition tests, the ND-treated rats spent more time drinking, an effect that was prominent for 11 weeks after the end of the treatment period. The ND-treated rats also displayed more frequently piloerection than the controls. The results indicate that ND has long-term effect on dominance in a provoking and competitive situation.

This study aimed at investigating the relationship between anxiety-like and depressive-like behaviour in mice. Therefore, we assessed the behaviour of mice from eight different strains (FVB/NA, BALB/c, C57BL/6, DBA/2, 129/Sv, C3H/He, CBA and BA) confronted first to anxiety models (the elevated plus-maze and the free exploratory test) and then to tests of depressive-like behaviours (forced swim test and unpredictable subchronic mild stress). In the forced swim test, mice from the DBA/2, the BA and the C3H/He strains displayed higher immobility than mice from the 129/Sv, the BALB/c, the C57BL/6 and the CBA strains. In the subchronic mild stress, mice from the C57BL/6 and the CBA strains displayed low sensitivity when compared with mice from all the others strains. A stepwise multiple regression analysis suggests that behaviour in the elevated plus-maze is associated with the time of immobility in the forced swim test (20%) and with the susceptibility to the unpredictable subchronic stress procedure (31%). The behaviour in the free exploratory paradigm is slightly associated with behaviours in the two tests of depression. These results suggest that anxiety may be a factor contributing, among others, to the susceptibility to depressive-like behaviours.

Botulinum neurotoxins (BoNTs) act specifically on cholinergic nerve terminals, where they cause a sustained block of acetylcholine release, and therefore they are powerful tools to study the role of cholinergic neurons in neuronal processes. Peripheral effects of BoNTs are widely documented while central effects have not been studied. Here, we report for the first time on the central toxicity of BoNT serotypes A and B following their direct intracerebroventricular (icv) injection in CD1 mice. The LD50 values were found to be in the range 0.5-1.0 x 10(-6)mg/kg. We recorded the following signs preceding animal death: piloerection and weight decrease appear first, followed by temperature decrease, eyelid closure, loss of sensorimotor reflexes, dehydration, dyspnea. Mice died of heart or respiratory failure. The surviving mice recovered completely within 4-6 days and regained the initial healthy conditions. At sub-lethal doses, the same clinical signs appear in a lighter form and with a longer time course.

This work was performed to clarify the differences between a long or short development of morphine dependence as well as between a recently installed or a long-term dependence. Morphine withdrawal in rats is a well-characterized phenomenon but this is not so in mice. A study of the principal withdrawal signs have been performed in mice, evaluating their specificity and particular profile of appearance in each type of dependence. Mice were divided into two groups that received increasing doses of morphine every 24 h, three groups that received increasing doses of morphine twice a day for 3 days, and a control group that received saline. Naloxone-induced opiate withdrawal was evaluated following short-term exposition to morphine [Test 1 (T1)—saline and Test 2 (T2)—naloxone] and long-term exposition to morphine [Test 3 (T3)—naloxone and Test 4 (T4)—saline]. Morphine administration twice a day is more effective in inducing opiate dependence than once a day, and with the latter, the duration of morphine exposure increases the intensity of withdrawal signs. Weight loss, diarrhea, body shakes, jumping, paw tremor, ptosis, piloerection, and the modified Gellert–Holtzman scale for mice are specific patterns of naloxone-induced withdrawal. The first four signs allow the discrimination between different levels of opiate dependence. Body care, piloerection, and the modified Gellert–Holtzman scale could be useful to detect conditioned withdrawal.

We demonstrated emotional piloerection in mice given conditioned fear stress by means of a pass-through apparatus. The emotional piloerection was first assessed in mice of different ages. The results showed that the piloerection changed with age. Pharmacological studies showed that the piloerection was inhibited by an alpha 1-adrenoceptor antagonist prazosin, but, surprisingly, was not inhibited by anxiolytic diazepam. These findings strongly suggest that the neuronal system of piloerection is different from that of freezing behavior, and that the neuronal system of piloerection develops with age.

The present study elucidates the behavioral and toxic signs in rats following dermal application of sulphur mustard (SM). Graded doses of SM (0.10, 0.25, 0.50, 0.75 and 1.0 LD50) were topically applied to male Wister rats. The body weight as well as behavioral/toxic signs and symptoms were recorded at 1, 2, 3, and 4th day after application of SM. Sulphur mustard consistently decreased body weights of rats in a dose and time dependent manner with maximum decrease on 3rd day post treatment. Sedation and diarrhea were significant in response to doses of SM intoxication in rats. It is concluded that the body weight, sedation and diarrhea may be used as a reliable parameter in evaluating SM intoxication. It is also suggested that hydration and hypertonic saline must be used as a rescue agent within 1-3 days after exposure to SM.

The relationship between parental care received and physiological and behavioral responses to parental separation, isolation, and reunion was investigated in seven juvenile Goeldi's monkey living in their family groups. Physiological responses were measured non-invasively: the hypothalamic-pituitary-adrenal axis via urinary cortisol output and the autonomic nervous system via piloerection on the tail. Parent-infant aggression demonstrated high intergroup variation and predicted: (a) an increase in urinary cortisol output, r(s) = 0.86, p = 0.04, and duration of piloerection, r(s) = 0.71, p = 0.08, at initial separation-isolation; (b) adaptation of piloerection, r(s) = -0.89, p = 0.03, to repeated separation-isolation. Juvenile Goeldi's monkeys that had received high parental aggression were more physiologically responsive to separation; they also sought more contact with their mothers at reunion, rs = 0.93, p = 0.02. We propose that these data are consistent with the hypothesis that high emotional reactivity is related to insecure attachment to aggressive parents in this New world primate.

The effects of IV TRH pretreatment on induction of anesthesia with propofol or pentobarbital were investigated in rats. The effects of IV TRH, administered after induction, on duration of propofol anesthesia and the interaction with atropine were also studied. The doses of propofol or pentobarbital were not influenced by TRH. TRH reduced duration of anesthesia after propofol, with higher brain concentrations of propofol at recovery. Atropine did not block this effect, but given alone prolonged duration of anesthesia. It is concluded that TRH shortens the duration of propofol anesthesia, probably due to a pharmacodynamic effect and not to a pharmacokinetic interaction.

A novel method to selectively lesion preganglionic sympathetic neurones has been combined with immunohistochemistry to study the expression of peptides in the rat superior cervical ganglion (SCG). Thus, systemic administration of monoclonal antibodies against acetylcholinesterase (AChE) caused a marked reduction in the number of enkephalin (ENK)-positive fibres and a total disappearance of fibres immunoreactive for calcitonin gene-related peptide (CGRP) and AChE in the SCG. A marked increase in the number of galanin/galanin message-associated peptide (GAL/GMAP)-immunoreactive cell bodies was also observed. The present results indicate that probably all CGRP and most ENK containing fibres in the rat SCG are of preganglionic origin and that peptides not normally expressed in SCG neurones, e.g. GAL and GMAP, can be upregulated after deafferentation.

In the rat, systemic administration of murine monoclonal antibodies against acetylcholinesterase caused rapid piloerection and ptosis (within 30–60 min after the injection). Using indirect immunohistochemistry the effect of these antibodies on peptides and enzyme expression was studied in the rat adrenal gland. Four days after antibody administration a total disappearance of acetylcholinesterase-immunoreactive fibers was observed. However, groups of acetylcholinesterase-immunoreactive chromaffin cells and intramedullary ganglion cells, both cell types showing acetylcholinesterase immunoreactivity also in the control adrenal medulla, expressed increased immunoreactivity. Analysis revealed that the acetylcholinesterase-immunoreactive chromaffin cell groups lackedphenylethanolamine- N -methyltransferase staining both in controls and treated rats. Antibody administration also affected levels of several peptides present in nerve fibers and chromaffin cells. Thus, the number of cells expressing enkephalin, calcitonin gene-related peptide and galanin was dramatically increased compared to the very few cells observed containing these three peptides in the normal gland. The majority of cells expressing enkephalin after antibody treatment also showedphenylethanolamine- N -methyltransferase immunoreactivity. In contrast, the few chromaffin cells expressing strong enkephalin-like immunoreactivity in controls werephenylethanolamine- N -methyltransferase negative. The sparse networks of calcitonin gene-related peptide- and galanin-positive fibers found in control adrenals were unchanged after the antibody treatment. However, the dense network of enkephalin varicose fibers totally disappeared after the antibody injection. A few substance P- and somatostatin-immunoreactive cells, not present in the normal gland, appeared after administration of the antibodies, whereas no changes were encountered with regard to immunoreactive nerve fibers. No clear differences between normal and treated animals could be observed in chromaffin cells with regard to immunoreactivity for neuropeptide Y or any of the four catecholamine-synthesizing enzymes, tyrosine hydroxylase, aromatic l-amino acid decarboxylase, dopamine β-hydroxylase orphenylethanolamine- N -methyltransferase. The present findings demonstrating a disappearance of acetylcholinesterase- and enkephalin-immunoreactive nerve fibers in the adrenal gland after intravenous injection of acetylcholinesterase antibodies support earlier reports showing that these antibodies cause degeneration of preganglionic fibers, and that neuronal decentralization of the adrenal gland induces marked increases in the levels of several peptides in chromaffin cells.

A preliminary dose-range finding study and a 13-week toxicity study were performed in male cynomolgus monkeys with catena-(S)-[mu-[N a-(3-aminopropionyl) histidinato (2-)-N1,N2,O:N tau]-zinc] (Z-103, CAS 107667-60-7), a novel anti-peptic ulcer agent, as part of a safety evaluation program. In the preliminary ascending dose study emesis was observed in animals treated at 625 mg/kg and transient reductions in food intake with associated body weight loss in a male treated at 625 or 312.5 mg/kg. Plasma zinc levels were also increased in all animals treated at 625 or 312.5 mg/kg. As a result dosages of 0, 20, 63 and 200 mg/kg/day were selected for the 13-week toxicity study. In this study, treatment-related changes were confined to the 200 mg/kg/day dosage and consisted of emesis, piloerection and transient body weight loss in one animal, increased plasma zinc concentrations, and zinc and copper deposition in the liver and kidneys without any associated morphological change. The no observed effect level was estimated to be 63 mg/kg/day in this study.

Guinea pig pups were either not injected (NI) or given SC injection of either saline vehicle (SAL) or 14 μg of corticotropin-releasing factor (CRF). In an isolation test, mean number of vocalizations and several measures of locomotor activity were markedly lower for CRF pups than for NI or SAL controls. CRF pups defecated less than did SAL pups. No differences were found among conditions for self-grooming. Behavioral freezing was shown by only two pups in the entire study. Significantly more CRF pups displayed piloerection, eye-closing, and a characteristic crouched stance than did controls. In a defensive withdrawal test, no differences among conditions were found for the proportion of pups entering a darkened chamber or for the latency to enter the chamber; however, CRF pups entered the chamber significantly fewer times during the 60-min test than did controls. There were no differences among conditions in the distance swum or number of turns made in a forced-swim test. These results replicate our earlier findings that peripheral injection of CRF suppresses vocalizing and a measure of locomotor activity in isolated guinea pig pups and identifies a number of additional behavioral effects. Of central interest here, the results indicate that the suppression of vocalizing and locomotion during isolation is not due to an increase in competing stress-related behavior or to diminished motor capacity.

The purpose of the present study was to investigate physical dependence upon diazepam systematically in two inbred strains of rats, Lewis (LEW) and Fischer 344 (F344). Rats were chronically fed food containing diazepam on an escalating drug dosage schedule, from 1 and 2 to 12 mg/g of food, over a period of 30 days. During treatment, the growth curve in LEW and F344 rats was suppressed compared with the respective controls. Motor incoordination was evaluated by a rotarod performance test. The ranking of the motor incoordination during the final concentration of diazepam was as follows: F344 > LEW. After substitution of normal food for the diazepam-admixed food, various signs of diazepam withdrawal occurred 16–120 h later. These signs included vocalization, irritability, muscle rigidity, ear-twitching, Straub's tail, piloerection, fascicular twitch, tremor, convulsion, and death. The incidences of vocalization, ear-twitching, piloerection, and tremor in F344 were significantly higher than those in LEW rats. Furthermore, two of six F344 rats showed spontaneous convulsions and one rat died of convulsions. Overall withdrawal scores were significantly greater in F344 (16.0) than in LEW (6.3) rats. These results suggest that diazepam withdrawal severity is strongly influenced by genetic factors, and F344 rats are highly susceptible to dependence upon benzodiazepines.

The effects of intracerebroventricular administration of morphine, the selective mu-agonist DAMGO, the delta-agonist DPDPE, the kappa-preferring peptide dynorphin A(1–13) and the kappaagonist U50,488H on locomotor behaviour in the guinea pig were investigated. Morphine (total dose = 0.01, 0.1, 1, 10, 200 nmol), DAMGO and DPDPE (total dose = 0.1, 1, 10, 100 nmol of each) produced piloerection and sedation, indicating that the responses of guinea pigs to mu- and delta-opioid agonists differed from those of rats and mice. In contrast, U50,488H (total dose = 10, 100 nmol) and dynorphin A(1–13) (total dose = 100 nmol) produced increased locomotor activity which was attenuated by pretreatment with naloxone and norbinaltorphimine, thus confirming the involvement of kappa-opioid receptors. Furthermore, pretreatment with spantide, baclofen, muscimol, bicuculline, MK-801, raclopride and atropine also inhibited the U50,488H-induced locomotor activity, suggesting the involvement of GABA, dopamine, excitatory amino acids, substance P and acetylcholine in this response.

The effects of morphine D-Pen2, D-Pen5 enkephalin (DPDPE) and U50,488H on the behavioural syndrome elicited by the dopamine (DA) D-2 agonist quinpirole, were investigated. Morphine (1, 5 and 15 mg/kg SC) and morphine administered intracerebroventricularly (ICV) (2 x 5 microliters, 10(-3) M; total dose = 10 nmol) produced piloerection and sedation. DPDPE-ICV (2 x 5 microliters and 2 x 10 microliters, 10(-3) M; total doses = 10 and 20 nmol) produced piloerection and sedation similar to morphine. U50,488H (1 mg/kg SC) induced locomotor activity and some stereotyped behaviour, whereas U50,488H (5 and 10 mg/kg SC) induced muscle rigidity and dystonic-like movements. The locomotor and behavioural response elicited by quinpirole (3 mg/kg IP) was attenuated in guinea-pigs pretreated with morphine (1, 5 and 15 mg/kg SC), morphine-ICV (2 x 5 microliters, 10(-3) M), and DPDPE-ICV (2 x 5 microliters and 2 x 10 microliters, 10(-3) M). These effects were reversed by naloxone (15 mg/kg SC). U50,488H (1 mg/kg SC) increased the quinpirole-induced locomotor activity, whereas U50,488H (5 and 10 mg/kg SC) decreased the locomotor activity and stereotyped behaviours produced by quinpirole. These results indicate that the gross behavioural effects of mu, delta and kappa opioids differ in guinea-pigs compared to other rodent species, and suggest differential involvement of these opioid receptor subtypes with DA D-2 receptor-mediated activity.