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The role of the brain renin-angiotensin system (RAS) in blood pressure (BP) and autonomic control isrecognized. However, the lack of the precise source of renin in the brain is one of the main barrierstowards a complete understanding of how the brain RAS operates. Here, we hypothesized that renin isexpressed in brain regions involved in sympathetic control such as the rostroventral lateral medulla(RVLM). We employed RNAscope, a highly sensitive and specific in situ hybridization technology.Surprisingly, the renin positive signals were absent in the RVLM, but we identified renin transcripts inthe nucleus ambiguus (NA), a site in the vicinity of the RVLM that contains cardiac vagal motoneurons.There was no signal in this region with the negative control scrambled probe. The signal strength wasgreater than that observed in other regions of the brain classically associated with the brain RAS. Wealso observed that the NA contains other necessary RAS components to produce angiotensin.Interestingly, renin was colocalized with cells expressing choline acetyltransferase (ChAT), suggesting itspossible role in cholinergic neurotransmission. Therefore, we generated mice lacking renin specifically incholinergic neurons (Ren-a ChAT-null ). Because we previously identified an alternative brain-specific reninisoform (ren-b) that elicits cardioprotective roles, we also generated mice lacking ren-b in cholinergicneurons (Ren-b ChAT-null ). At baseline, Ren-a ChAT-null exhibited a trend towards decreased BP, while Ren-b ChAT-null exhibited higher BP, although these differences were not statistically significant. Importantly,Ren-a ChAT-null exhibited an attenuated tachycardiac and pressor responses to atropine (pChAT-null exhibited an augmented pressor response to atropine (p

Background An early-life anxious temperament (AT) is a risk factor for the development of anxiety, depression, and comorbid substance abuse. We validated a nonhuman primate model of early-life AT and identified the dorsal amygdala as a core component of AT's neural circuit. Here, we combine RNA sequencing, viral-vector gene manipulation, functional brain imaging, and behavioral phenotyping to uncover AT's molecular substrates. Methods In response to potential threat, AT and brain metabolism were assessed in 46 young rhesus monkeys. We identified AT-related transcripts using RNA-sequencing data from dorsal amygdala tissue (including central nucleus of the amygdala [Ce] and dorsal regions of the basal nucleus). Based on the results, we overexpressed the neurotrophin-3 gene, NTF3, in the dorsal amygdala using intraoperative magnetic resonance imaging–guided surgery (n = 5 per group). Results This discovery-based approach identified AT-related alterations in the expression of well-established and novel genes, including an inverse association between NTRK3 expression and AT. NTRK3 is an interesting target because it is a relatively unexplored neurotrophic factor that modulates intracellular neuroplasticity pathways. Overexpression of the transcript for NTRK3's endogenous ligand, NTF3, in the dorsal amygdala resulted in reduced AT and altered function in AT's neural circuit. Conclusions Together, these data implicate neurotrophin-3/NTRK3 signaling in the dorsal amygdala in mediating primate anxiety. More generally, this approach provides an important step toward understanding the molecular underpinnings of early-life AT and will be useful in guiding the development of treatments to prevent the development of stress-related psychopathology.

BackgroundChildren exhibiting extreme anxious temperament (AT) are at an increased risk for developing anxiety and depression. Our previous mechanistic and neuroimaging work in young rhesus monkeys linked the central nucleus of the amygdala to AT and its underlying neural circuit.MethodsHere, we used laser capture microscopy and RNA sequencing in 47 young rhesus monkeys to investigate AT's molecular underpinnings by focusing on neurons from the lateral division of the central nucleus of the amygdala (CeL). RNA sequencing identified numerous AT-related CeL transcripts, and we used immunofluorescence (n= 3) and tract-tracing (n= 2) methods in a different sample of monkeys to examine the expression, distribution, and projection pattern of neurons expressing one of these transcripts.ResultsWe found 555 AT-related transcripts, 14 of which were confirmed with high statistical confidence (false discovery rate < .10), including protein kinase C delta (PKCδ), a CeL microcircuit cell marker implicated in rodent threat processing. We characterized PKCδ neurons in the rhesus CeL, compared its distribution with that of the mouse, and demonstrated that a subset of these neurons project to the laterodorsal bed nucleus of the stria terminalis.ConclusionsThese findings demonstrate that CeL PKCδ is associated with primate anxiety, provides evidence of a CeL to laterodorsal bed nucleus of the stria terminalis circuit that may be relevant to understanding human anxiety, and points to specific molecules within this circuit that could serve as potential treatment targets for anxiety disorders.

Background Nonhuman primate models are critical for understanding mechanisms underlying human psychopathology. We established a nonhuman primate model of anxious temperament (AT) for studying the early-life risk to develop anxiety and depression. Studies have identified the central nucleus of the amygdala (Ce) as an essential component of AT's neural substrates. Corticotropin-releasing factor (CRF) is expressed in the Ce, has a role in stress, and is linked to psychopathology. Here, in young rhesus monkeys, we combined viral vector technology with assessments of anxiety and multimodal neuroimaging to understand the consequences of chronically increased CRF in the Ce region. Methods Using real-time intraoperative magnetic resonance imaging-guided convection-enhanced delivery, five monkeys received bilateral dorsal amygdala Ce-region infusions of adeno-associated virus serotype 2 containing the CRF construct. Their cagemates served as unoperated control subjects. AT, regional brain metabolism, resting functional magnetic resonance imaging, and diffusion tensor imaging were assessed before and 2 months after viral infusions. Results Dorsal amygdala CRF overexpression significantly increased AT and metabolism within the dorsal amygdala. Additionally, we observed changes in metabolism in other AT-related regions, as well as in measures of functional and structural connectivity. Conclusions This study provides a translational roadmap that is important for understanding human psychopathology by combining molecular manipulations used in rodents with behavioral phenotyping and multimodal neuroimaging measures used in humans. The results indicate that chronic CRF overexpression in primates not only increases AT but also affects metabolism and connectivity within components of AT's neural circuitry.

Induced pluripotent stem cell (iPSC)-derived neurons represent an opportunity for cell replacement strategies for neurodegenerative disorders such as Parkinson's disease (PD). Improvement in cell graft targeting, distribution, and density can be key for disease modification. We have previously developed a trajectory guide system for real-time intraoperative magnetic resonance imaging (RT-IMRI) delivery of infusates, such as viral vector suspensions for gene therapy strategies. Intracerebral delivery of iPSC-derived neurons presents different challenges than viral vectors, including limited cell survival if cells are kept at room temperature for prolonged periods of time, precipitation and aggregation of cells in the cannula, and obstruction during injection, which must be solved for successful application of this delivery approach. To develop procedures suitable for RT-IMRI cell delivery, we first performed in vitro studies to tailor the delivery hardware (e.g., cannula) and defined a range of parameters to be applied (e.g., maximal time span allowable between cell loading in the system and intracerebral injection) to ensure cell survival. Then we performed an in vivo study to evaluate the feasibility of applying the system to nonhuman primates. Our results demonstrate that the RT-IMRI delivery system provides valuable guidance, monitoring, and visualization during intracerebral cell delivery that are compatible with cell survival.

Maternal overnutrition or associated complications putatively mediate the obesogenic effects of perinatal high-fat diet on developing offspring. Here, we tested the hypothesis that a Western diet developmental environment increases adiposity not only in male offspring from obesity-prone (DIO) mothers, but also in those from obesity-resistant (DR) dams, implicating a deleterious role for the Western diet per se. Selectively bred DIO and DR female rats were fed chow (17% kcal fat) or Western diet (32%) for 54 days before mating and, thereafter, through weaning. As intended, despite chow-like caloric intake, Western diet increased prepregnancy weight gain and circulating leptin levels in DIO, but not DR, dams. Yet, in both genotypes, maternal Western diet increased the weight and adiposity of preweanlings, as early as in DR offspring, and increased plasma leptin, insulin, and adiponectin of weanlings. Although body weight normalized with chow feeding during adolescence, young adult Western diet offspring subsequently showed decreased energy expenditure and, in DR offspring, decreased lipid utilization as a fuel substrate. By mid-adulthood, maternal Western diet DR offspring ate more chow, weighed more, and were fatter than controls. Thus, maternal Western diet covertly programmed increased adiposity in childhood and adulthood, disrupted relations of energy regulatory hormones with body fat, and decreased energy expenditure in offspring of lean, genetically obesity-resistant mothers. Maternal Western diet exposure alone, without maternal obesity or overnutrition, can promote offspring weight gain.

BACKGROUND AND PURPOSE Infusion of corticotropin-releasing factor (CRF)/urocortin (Ucn) family peptides suppresses feeding in mice. We examined whether rats show peripheral CRF/Ucn-induced anorexia and determined its behavioural and pharmacological bases. EXPERIMENTAL APPROACH Male Wistar rats (n= 5–12 per group) were administered (i.p.) CRF receptor agonists with different subtype affinities. Food intake, formation of conditioned taste aversion and corticosterone levels were assessed. In addition, Ucn 1- and Ucn 2-induced anorexia was studied in fasted CRF2 knockout (n= 11) and wild-type (n= 13) mice. KEY RESULTS Ucn 1, non-selective CRF receptor agonist, reduced food intake most potently (∼0.32 nmol·kg−1) and efficaciously (up to 70% reduction) in fasted and fed rats. The peptides' rank-order of anorexic potency was Ucn 1 ≥ Ucn 2 > >stressin1-A > Ucn 3, and efficacy, Ucn 1 > stressin1-A > Ucn 2 = Ucn 3. Ucn 1 reduced meal frequency and size, facilitated feeding bout termination and slowed eating rate. Stressin1-A (CRF1 agonist) reduced meal size; Ucn 2 (CRF2 agonist) reduced meal frequency. Stressin1-A and Ucn 1, but not Ucn 2, produced a conditioned taste aversion, reduced feeding efficiency and weight regain and elicited diarrhoea. Ucn 1, but not Ucn 2, also increased corticosterone levels. Ucn 1 and Ucn 2 reduced feeding in wild-type, but not CRF2 knockout, mice. CONCLUSIONS AND IMPLICATIONS CRF1 agonists, Ucn 1 and stressin1-A, reduced feeding and induced interoceptive stress, whereas Ucn 2 potently suppressed feeding via a CRF2-dependent mechanism without eliciting malaise. Consistent with their pharmacological differences, peripheral urocortins have diverse effects on appetite.

Dieting to control body weight involves cycles of deprivation from palatable food that can promote compulsive eating. The present study shows that rats withdrawn from intermittent access to palatable food exhibit overeating of palatable food upon renewed access and an affective withdrawal-like state characterized by corticotropin-releasing factor-1 (CRF 1 ) receptor antagonist-reversible behaviors, including hypophagia, motivational deficits to obtain less palatable food, and anxiogenic-like behavior. Withdrawal was accompanied by increased CRF expression and CRF 1 electrophysiological responsiveness in the central nucleus of the amygdala. We propose that recruitment of anti-reward extrahypothalamic CRF-CRF 1 systems during withdrawal from palatable food, analogous to abstinence from abused drugs, may promote compulsive selection of palatable food, undereating of healthier alternatives, and a negative emotional state when intake of palatable food is prevented.

Defeat is a social stressor involving subordination by a threatening conspecific. Type 2 corticotropin-releasing factor receptors (CRF(2)) are abundant in brain regions implicated in defeat responses and are putative stress-related molecules. The present study sought to determine whether neuroactivation and CRF(2) expression co-occurred at brain region or cellular levels following acute defeat. Male "intruder" Wistar rats were placed into the cage of an aggressive "resident" Long-Evans rat (n=6). Upon defeat, intruders (n=6) were placed in a wire-mesh chamber and were returned to the resident's cage for an additional 75 min. Controls (n=6) were handled and returned to their home cage for the same duration. Coronal brain sections were stained for an immediate early gene product, Fos, as a neuronal activation marker. Combined immunohistochemistry with in situ hybridization was performed on a subset of brain sections from defeated intruders to visualize Fos immunoreactivity and CRF(2) mRNA jointly. Defeated rats had fivefold, sevenfold, and 10-fold more Fos-positive cells than controls in the arcuate, ventromedial nucleus of the hypothalamus, and medial amygdala post-defeat. Significant colocalization of CRF(2) mRNA and Fos-positive cells was observed in the posterior medial amygdala but not in the arcuate nucleus or ventromedial hypothalamus. The results indicate CRF(2) receptor-positive neurons in the posterior medial amygdala are involved in the neural response to social defeat.

Lateral hypothalamic orexin expressing neurons send fibers to various brain areas such as the brainstem, hypothalamus, cortex and limbic system, including the amygdala and the bed nucleus of stria terminalis (BST). The role of orexins in reward seeking, response to stress, learning and memory have recently been investigated. BST is known to be involved in the regulation of hormonal and behavioral responses to stress, anxiety and sexual behavior. The present study aimed to elucidate the involvement of orexin-A (OXA) in learning, anxiety and reinforcement processes in the BST. Bilateral OXA microinjections in the doses of 250 ng (70 pmol) and 500 ng (140 pmol) into the BST of male Wistar rats were performed 30 min prior to open field (OPF), elevated plus maze (EPM), conditioned place preference (CPP), or passive avoidance (PAV) tests. In the CPP, 250 ng OXA increased the number of entering into the treatment quadrant. The 500 ng OXA had significant anxiolytic effects on EPM. There was a mild increase in the locomotor activity in the OPF as well as in the EPM. In the PAV, OXA dose-dependently reduced the retention time to enter the dark room, indicating its suppressive effect on avoidance learning. Our findings reveal that OXA shows functional heterogeneity in learning and memory processes having a specific role in the modulation of PAV learning. The inhibition on avoidance learning is supposed to be due to the anxiolytic effect of OXA.

Urocortins, three paralogs of the stress-related peptide corticotropin-releasing factor (CRF) found in bony fish, amphibians, birds and mammals, have unique phylogenies, pharmacologies, and tissue distributions. As a result and despite a structural family resemblance, the natural functions of urocortins and CRF in mammalian homeostatic responses differ substantially. Endogenous urocortins are neither simply counterpoints nor mimics of endogenous CRF action. In their own right, urocortins may be clinically relevant molecules in the pathogenesis or management of many conditions, including congestive heart failure, hypertension, gastrointestinal and inflammatory disorders (irritable bowel syndrome, active gastritis, gastroparesis, rheumatoid arthritis), atopic/allergic disorders (dermatitis, urticaria, asthma), pregnancy and parturition (preeclampsia, spontaneous abortion, onset and maintenance of effective labor), major depression and obesity. Safety trials for intravenous urocortin treatment have already begun for the treatment of congestive heart failure. Further understanding the unique functions of urocortin 1, urocortin 2 and urocortin 3 action may uncover other therapeutic opportunities.

Bombesin-like peptides including gastrin releasing peptide and neuromedin C are known to inhibit feeding. Bombesin receptors have been found in moderate to high densities in the amygdaloid body, which is essentially involved in the regulation of feeding and body weight. In the present experiments neuromedin C (15, 30, and 60 ng), a carboxyterminal decapeptid fragment of gastrin releasing peptide, was bilaterally microinjected into the central part of the amygdala in ad libitum fed male CFY rats. Food intake was measured every 5 min for 30 min and also 60 min following neuromedin C or vehicle microinjections. Fifteen nanograms neuromedin C significantly suppressed liquid food consumption for 5 min and 30 ng for 25 min. However, 60 ng was not effective. Neuromedin C effects were blocked by prior application of the bombesin receptor antagonist [Leu 13 -ψ(CH 2 NH)-Leu 14 ]-bombesin. Neuromedin C treatment increased latency to feeding, decreased food intake, decreased the time spent feeding and their ratio, the number and the duration of feeding episodes during the first 5 min, without modifying body temperature or stereotype activity. Results indicate that neuromedin C may decrease the efficiency of feeding and that activation of bombesin receptors in the central amygdala may reduce appetite.

Brain corticotropin-releasing factor/urocortin (CRF/Ucn) systems are hypothesized to control feeding, with central administration of 'type 2' urocortins producing delayed anorexia. The present study sought to identify the receptor subtype, brain site, and behavioral mode of action through which Ucn 3 reduces nocturnal food intake in rats. Non-food-deprived male Wistar rats (n=176) were administered Ucn 3 into the lateral (LV) or fourth ventricle, or into the ventromedial or paraventricular nuclei of the hypothalamus (VMN, PVN) or the medial amygdala (MeA), regions in which Ucn 3 is expressed in proximity to CRF(2) receptors. LV Ucn 3 suppressed ingestion during the third-fourth post-injection hours. LV Ucn 3 anorexia was reversed by cotreatment with astressin(2)-B, a selective CRF(2) antagonist and not observed following equimole subcutaneous or fourth ventricle administration. Bilateral intra-VMN and intra-PVN infusion, more potently than LV infusion, reduced the quantity (57-73%) and duration of ingestion (32-68%) during the third-fourth post-infusion hours. LV, intra-PVN and intra-VMN infusion of Ucn 3 slowed the eating rate and reduced intake by prolonging the post-meal interval. Intra-VMN Ucn 3 reduced feeding bout size, and intra-PVN Ucn 3 reduced the regularity of eating from pellet to pellet. Ucn 3 effects were behaviorally specific, because minimal effective anorectic Ucn 3 doses did not alter drinking rate or promote a conditioned taste aversion, and site-specific, because intra-MeA Ucn 3 produced a nibbling pattern of more, but smaller meals without altering total intake. The results implicate the VMN and PVN of the hypothalamus as sites for Ucn 3-CRF(2) control of food intake.

Orexins are expressed by lateral hypothalamic neurons which project to numerous brain regions such as the cortex, hypothalamus, brainstem and the limbic system including the amygdala (AMY) and the bed nucleus of stria terminalis (BST). Orexinergic system coordinates the metabolic, motivational, motor, autonomic and arousal processes necessary to elicit environmentally appropriate behaviors. In our previous experiments, orexin-A (OXA) microinjections into the BST evoked dose-dependent increase of liquid food and water intake. Since in the BST high level of orexin-1 receptor (OX1R) mRNA was observed, in the present experiments the effect of selective OX1R antagonist SB334867 was examined in male Wistar rats. One hundred ng (0.26 nmol) SB334867 was microinjected bilaterally alone or 15 min prior 500 ng (0.14 nmol) OXA bilateral microinjections to prove whether the effects of OXA on liquid food and water intake can be antagonized. OXA significantly enhanced liquid food consumption and water intake, and these effects could be antagonized by SB334867. Application of the antagonist SB334867 alone did not modify intakes. Our results show that OXA induced enhancement on liquid food ingestion and water intake can be antagonized by SB334867 indicating that these effects are mediated by OX1Rs in the BST.

Attempts to understand ingestion have sought to understand the control of meals. The present study evaluated a meal definition that included prandial drinking (drinking-explicit meals). The spontaneous nocturnal intake of male Wistar rats was studied. The meal breakpoint was defined as the interval between feeding or drinking events providing the most stable estimate of meal structure. Alternative breakpoints derived from prevailing methodology, log-survivorship, or frequency histogram analysis of interfeeding intervals without respect to drinking were compared (drinking-naive meals). Threshold interfeeding intervals that accounted for drinking indirectly were evaluated as surrogate breakpoints (drinking-implicit meals). Definitions were compared by determining which criterion better conformed to predictions of satiety. Microstructural differences resulting from the definitions were also studied. Under the drinking-explicit definition, rats averaged nine or ten 13-min meals/night, during which they consumed food and water equally in duration (5–6 min) and quantity (2.3 g). Individual differences were observed in microstructure measures. Meals defined by drinking-informed, but not drinking-naive, methods were followed by the behavioral satiety sequence and by an initially low likelihood of resuming feeding that monotonically increased with time. The drinking-explicit definition uniquely revealed preprandial and postprandial correlations of similar magnitude. Under drinking-informed definitions, food restriction increased meal size, whereas drinking-naive definitions increased meal frequency. Drinking-implicit definitions provided workable approximations of meal frequency and size but inferior estimates of feeding duration, eating rate, and the preprandial correlation. Thus log-survivorship analysis is not appropriate for identifying meal breakpoints, and the consideration of drinking in meal definitions can provide a better estimate of meal structure.

It has been demonstrated that the basolateral amygdala (ABL) represents a satiety mechanism. Experimental data indicate that peripheral or central applications of neuropeptide bombesin (BN) and BN-like peptides inhibit feeding. Since the amygdala (AMY) is rich in BN-like immunoreactive elements, the present study was performed to determine whether 10 or 40 ng doses of BN microinjected bilaterally into the ABL could modify solid food intake. Twenty nanograms of BN (10 ng per injection site) in 24-h deprived rats caused transient inhibition of food intake and 80 ng resulted in a significant reduction of food consumption for 1 h. This inhibitory effect of BN on feeding was eliminated by prior BN antagonist treatment. Results of behavioral tests showed that BN microinjections into the ABL specifically reduced food intake without altering behavioral patterns or influencing the body temperature. Present results suggest that BN-like peptides may act as a complex satiety signal in the ABL.

Urocortin 2 (Ucn 2) is a corticotrop releasing factor paralog peptide with many physiological functions and it has widespread distribution. There are some data on the cytoprotective effects of Ucn 2, but less is known about its neuro- and retinoprotective actions. We have previously shown that Ucn 2 is protective in ischemia-induced retinal degeneration. The aim of the present study was to examine the protective potential of Ucn 2 in monosodium-glutamate (MSG)-induced retinal degeneration by routine histology and to investigate cell-type specific effects by immunohistochemistry. Rat pups received MSG applied on postnatal days 1, 5 and 9 and Ucn 2 was injected intravitreally into one eye. Retinas were processed for histology and immunocytochemistry after 3 weeks. Immunolabeling was determined for glial fibrillary acidic protein, vesicular glutamate transporter 1, protein kinase Cα, calbindin, parvalbumin and calretinin. Retinal tissue from animals treated with MSG showed severe degeneration compared to normal retinas, but intravitreal Ucn 2 treatment resulted in a retained retinal structure both at histological and neurochemical levels: distinct inner retinal layers and rescued inner retinal cells (different types of amacrine and rod bipolar cells) could be observed. These findings support the neuroprotective function of Ucn 2 in MSG-induced retinal degeneration.

Hormones and visceral neural feedback signal the brain to stimulate or inhibit appetite in the service of energy homeostasis. Much of this peripheral feedback directly converges on the mediobasal hypothalamus, including the arcuate nucleus of the hypothalamus and its ascending projections to other hypothalamic nuclei; the caudal brainstem, through vagal afferents and endocrine transmission; and on brain reward pathways, such as the mesolimbic dopamine system. These feedback integration sites in the central nervous system (CNS) intercommunicate to achieve a coordinated control of food intake with both energy and nonenergy homeostatic components.

Urocortin 2 (Ucn 2) is corticotropin-releasing factor (CRF) paralog that preferentially activates CRF(2) receptors. Ucns exert CRF(2)-mediated cytoprotective effects against ischemia-reperfusion injury in cardiomyocytes. However, little is known regarding potential retinoprotective effects of Ucns despite the known presence of CRF family peptides and their receptors (predominantly CRF(2 alpha)) in retina. Therefore, the present study investigated the effects of post-ischemic intravitreal Ucn 2 (2 nmol) administration on ischemia-induced retinal degeneration. Two-month-old rats were subjected to permanent bilateral common carotid artery occlusion, and their retinas were processed histologically after two weeks survival to determine the density of viable cells in the ganglion cell layer and the thickness of all retinal layers. In vehicle-treated subjects, carotid occlusion reduced retina thickness by approximately 60% as compared to sham-operated animals. In contrast, intraocular Ucn 2 treatment led to a marked amelioration of the retinal layers, and the thickness of all layers was significantly increased by 40% compared to ischemic vehicle-treated subjects. Ucn 2 treatment also increased the number of cells by 55% in the ganglion cell layer as compared to those from carotid-occluded retinas of vehicle-treated subjects. These findings suggest that intraocular Ucn 2 treatment may protect against ischemia-induced retinal degeneration, results with potential therapeutic implications for ophthalmic diseases.

The corticotropin-releasing factor (CRF) system mediates stress responses. Extrahypothalamic CRF1 receptor activation has anxiogenic-like properties, but anxiety-related functions of CRF2 receptors remain unclear. The present study determined the effects of intracerebroventricular administration of a CRF2 agonist, urocortin 3, on behavior of male Wistar rats in the shock-probe, social interaction, and defensive withdrawal tests of anxiety-like behavior. Equimolar doses of stressin1-A, a novel CRF1 agonist, were administered to separate rats. The effects of pyrazolo[1,5-a]-1,3,5-triazin-4-amine,8-[4-(bromo)-2-chlorophenyl]-N, N-bis(2-methoxyethyl)-2,7-dimethyl-(9Cl) (MJL-1-109-2), a CRF1 antagonist, on behavior in the shock-probe test also were studied. Stressin1-A increased anxiety-like behavior in the social interaction and shock-probe tests. Stressin1-A elicited behavioral activation and defensive burying at lower doses (0.04 nmol), but it increased freezing, grooming, and mounting at 25-fold higher (1-nmol) doses. Conversely, systemic administration of MJL-1-109-2 (10 mg/kg) had anxiolytic-like effects in the shock-probe test. Unlike stressin1-A or MJL-1-109-2, i.c.v. urocortin 3 infusion did not alter anxiety-like behavior in the shock-probe test across a range of doses that reduced locomotion and rearing and increased grooming. Urocortin 3 also did not decrease social interaction, but it decreased anxiety-like behavior in the defensive withdrawal test at a 2-nmol dose. Thus, i.c.v. administration of CRF1 and CRF2 agonists produced differential, but not opposite, effects on anxiety-like behavior. Urocortin 3 (i.c.v.) did not consistently decrease or increase anxiety-like behavior, the latter unlike effects seen previously after local microinjection of CRF2 agonists into the septum or raphe. With increasing CRF1 activation, however, the behavioral expression of anxiety qualitatively changes from "coping" to "noncoping" and offensive, agonistic behaviors.

Our recent results showed that angiotensin II or III (AII, AIII) microinjected into the zona incerta (ZI) significantly increased water intake. The most effective doses of AII and AIII were also defined. The two neuropeptides had their effects differently on drinking via different receptors. AII bound to AT(1) that was blocked by AT(1) receptor antagonist Losartan and the effect of AIII was eliminated by prior application of AT(2) receptor antagonist PD 123319. After different hydrational challenges, the effects of AII and AIII in the ZI have never been experimented, however. In the present experiments, the previously defined effective doses of AII (100 ng) or AIII (200 ng) were microinjected into the ZI after different types of challenges: (1). lowered thirst motivation when animals ingested approximately 40% of their daily fluid need during the consequent 60-min-daily-drinking period before the injection, (2). 48-h water deprivation, (3). intracellular dehydration and (4). extracellular dehydration. In all of the cases, incertally injected AII increased the animals' water ingestion. While Losartan could block these effects, PD 123319 was ineffective. Experiments were repeated by AIII, but in none of the cases differences were experienced between the groups. The finding that following hydrational challenges water intake increased only after AII injections and it could be blocked only by Losartan suggests that AII and AT(1) receptor play a pivotal role in the ZI in maintaining the body water balance.

Different doses of angiotensin II (AII) or angiotensin III (AIII) microinjections into the zona incerta have been studied on drinking of rats in separate experiments during the consequent 60-min-daily-drinking period. Also, the dipsogen power of only the effective dose of AII and AIII was compared to vehicle treated rats. After, angiotensin receptor (AT(1), AT(2)) antagonists on AII or AIII induced drinking were tested. In the first and second experiments only the 100 ng AII and the 200 ng AIII increased water intake significantly. In the third experiment the AII started its dipsogen effect earlier, at the 5 min measuring time, compared to the AIII. Both effects kept on lasting parallel from the 10 min on. Considering the antagonist pre-treatments in the fourth experiment, animals were injected with 90 ng losartan, an AT(1) antagonist, 180 ng PD 123319 or 200 ng CGP 42112, both AT(2) antagonists, respectively. Both AII and AIII increased water consumption. The effect of AII could be blocked by losartan, but not by PD 123319 or CGP 42112. On the other hand, the effect of AIII could not be blocked by losartan, but by both the PD 123319 and CGP 42112. Since, the effects of AII, AIII and angiotensin antagonists have not been tested in the zona incerta, the finding that water intake increased after AII or AIII injections and it could be blocked only by either of the antagonists suggests that AT(1) and AT(2) receptors play partially different roles in the regulation of water intake.

Bombesin (BN)-like peptides including gastrin-releasing peptide (GRP) are known to inhibit feeding. In the amygdaloid body BN receptors have been found in moderate to high densities. The central part of the amygdala (ACE) is essentially involved in the regulation of feeding and body weight. In the present experiments GRP was injected into the ACE and liquid food intake, general behavioural activity, as well as core temperature, were examined in male CFY rats. Food intake was measured every 5 min for 30 min and at the 40th and the 60th min following GRP or vehicle microinjections. Bilateral application of 50, 100 or 150 ng GRP resulted in transient inhibition of food intake while bilateral injection of 25 or 300 ng GRP did not modify feeding. Effect of GRP was eliminated by prior application of BN receptor antagonist [Leu13-ψ(CH2NH)-Leu14]BN. After GRP or vehicle treatments animals were video-monitored and food intake, the first meal latency (FML), intermeal intervals (IMI), the time spent feeding (FT), grooming, resting and exploration were analysed at 5-min intervals for 30 min. However, FML did not change after GRP, the first IMI increased and intake, FT and intake/FT significantly decreased during the first 5 min. Duration of resting gradually increased after GRP and animals spent less time with exploration after GRP treatment than after vehicle injection. These differences were significant during the 25–30-min period. In body temperature, no significant changes were observed. Our results show that GRP in the ACE inhibits feeding and that GRP may decrease the efficiency of eating and may act as a satiety signal.

The present study was performed to determine whether low doses (10 or 40 ng) of bombesin microinjected into the amygdala could modify solid food intake. Forty ng of bombesin in 24 h deprived rats caused transient inhibition of food intake. This inhibitory effect was eliminated by prior bombesin antagonist treatment. A series of quantitative behavioral tests indicated that low doses of bombesin application specifically reduced food intake without altering the behavioral pattern or influencing the body temperature. The present results suggest, that bombesin-like peptides may act as a satiety signal in the central part of the amygdala.

Subjects searched for a chromatic target among coloured background items. With low target-background chromatic similarity, response latencies remained uniformly short whether the target was present or not and whether the items were chromatically homogeneous or not. Latencies increased with increases in target-background similarity and were longest with heterogeneous backgrounds, with which the effects of trial also became manifest. We employed Treisman's model of visual search to account for these findings. In particular, we suggest that similarity increases forced a shift from a preattentive to an attentive search, the latter being importantly shaped by the background's level of chromatic variance.