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The passage of a pulse wave via an intact segment of a dog's thoracic aorta, its denerved autograft, and thoracic aortal allograft from a dog donor, was studied using equipment for arterial pressure measurement and tensometry of longitudinal and transversal blood vessel deformations at the point of pressure measurement. The frequency characteristics of the equipment were adjusted beforehand. The experiment demonstrated the impossibility of the formation and spread of a normal solitary pulse wave and preservation of laminar blood flow without an intact aortal innervation. Optimal blood flow hydrodynamics in the aorta is possible only in the presence of the system for neuroreflectory control of each wave passing; the system must determine the solitary character of the wave and provide antifluttery stabilization for blood flow.

The role of endogenous opioid system in learning (Pavlovian conditioning) and reinforcement was studied in newborn rats by pairing central injection of dynorphin A (1-13), an endogenous ligand with high affinity for kappa opioid receptors, with a surrogate nipple. For conditioning, the nipple served as the conditioned stimulus and dynorphin as the unconditioned stimulus. Dynorphin was found to elicit an immediate unconditioned, dose-dependent increase in the neonatal responsiveness to a surrogate nipple providing water, an effect apparently mediated through the kappa opioid receptors. This immediate effect of dynorphin was evident in the context of suckling behavior but not in the context of adult-like drinking when water was delivered through an intra-oral cannula. One hour after injection, the unconditioned stimulatory effect of dynorphin had dissipated and no longer affected responsiveness to the nipple. However, pairing of centrally injected dynorphin and suckling on a nipple delivering water substantially enhanced responsiveness to a nipple 1h later. This suggested conditioning, and hence reinforcement, by the centrally injected dynorphin. The conditioned sustained nipple attachment was mediated through both kappa and micro opioid receptors. These experiments confirm a central role for the brain opioid systems in reinforcement of neonatal behavior on the nipple.

Toward understanding why infant rats ingest high levels of ethanol without initiation procedures, the authors tested effects of mu and kappa receptor antagonists on ethanol reinforcement in neonatal rats. After an intracisternal injection of CTOP (micro antagonist), nor-Binaltorphimine (kappa antagonist), or saline, newborn (3-hr-old) rats were given conditioning pairings of an odor with intraorally infused ethanol or a surrogate nipple with ethanol administered intraperitoneally (to minimize ethanol's gustatory attributes). In each case, these opioid antagonists reduced or eliminated ethanol's reinforcement effect. The same effects occurred with saccharin as the reinforcer in olfactory conditioning. The results imply that activation of mu and kappa receptors, apparently acting jointly, is necessary for reinforcement or that antagonists of this activity impair basic conditioning., (((c) 2006 APA, all rights reserved).)

The present study compared intake of sweet (saccharin), bitter (quinine), and neutral (water) tastants available either in the context of suckling behavior through a surrogate nipple or independent adultlike feeding through an intraoral cheek cannula in 3-hr-old newborn rats lacking any suckling experience and 24-hr-old rats with regular experience with the dam's nipple. The new technique of online monitoring of fluid flow was applied for assessment of the temporal patterns of ingestion. Newborn and 1-day-old rats tested in the context of suckling behavior showed extremely low intake of quinine, moderate intake of water, and high intake of saccharin. In the same way, they demonstrated low intake of quinine and high intake of saccharin in the context of independent feeding, but intake of water was also high and comparable to that of saccharin. Suckling rats attained higher efficacy of fluid extraction from nipple than pups drinking from cannula. The differential responsiveness to quinine, saccharin, and water in suckling rats was also manifested through attachment behavior, with pups spending less time on the nipple providing quinine and more time on the nipple with saccharin than on the nipple providing water. These results suggest that neonates show taste differentiation as early as 3 hr after birth, and that this taste differentiation is more pronounced in the context of suckling behavior than in the context of adultlike, independent ingestion., ((c) 2006 Wiley Periodicals, Inc. Dev Psyshobiol 48: 133-145, 2006.)

Responsiveness to a surrogate nipple providing water, 0.1% saccharin, 10% sucrose, pedialyte, or milk was tested in naïve-to-suckling newborn rats during six 10-min exposures, one every 1.5 h over a 7.5 h period. Across a succession of exposures, newborn rats repeatedly attached to and ingested milk from a surrogate nipple, yielding significant body weight gain and increased concentration of blood plasma glucose. Initially, pups ingested considerable amounts of saccharin and sucrose, but then dramatically decreased their consumption of these fluids across the experimental sessions. Intake of milk was significantly higher than that of all other substances. Blood glucose concentration in pups treated with water, saccharin, sucrose, and pedialyte did not differ significantly from that of non-treated pups. The present data suggest a potential contribution of a fluid's palatability and nutritive value in the persistence and efficacy of diet intake for neonatal rats in the context of suckling behavior.

Using light and electron microscopic methods, the histogenesis and structural organization of the walls of rat venae cavae and pulmonary veins were studied in prenatal and postnatal periods of development. The special attention was paid to the appearance of the striated myocytes in the walls of these vessels during the process of ontogenesis. The time of initial divergent development of myoblastic differon was established, the stages of differentiation of striated myoblasts and the peculiarities of intercellular junctions were characterized, as well as the innervation and vascularization of the walls of venae cavae and pulmonary veins.

Newborn rats, 3 hr after birth and before any experience in suckling, were exposed for 10 min to a surrogate nipple providing milk. One hour later, they were exposed to an empty nipple for another 10-min period. The basic characteristics of oral behavior (oral compression activity, OCA) were assessed by recording intranipple pressure during the pups' first attachment to a nipple. The peculiarities of milk-induced changes of OCA were examined with three modes of milk delivery (milk infusions, and intermittent and continuous milk deliveries). The pattern of OCA exerted by the newborn pups on a surrogate nipple consisted of rhythmic oscillations within a frequency range of 0.4 to 1.0 Hz superimposed on slow (frequency < 0.2 Hz), irregular intranipple pressure fluctuations. Oral behavior during the first minute after oral capture of the nipple differed significantly from that during any subsequent 1-min interval in terms of frequency content of OCA. The pattern of OCA changes induced by milk infusions or intermittent milk delivery included an abrupt rise in intranipple pressure, accompanied or followed by a burst of fast nipple compressions (bites). Our data suggest that newborn rats attached to a surrogate nipple demonstrate patterns of oral behavior that simulate, in terms of basic frequency characteristics, patterns of nutritive and nonnutritive suckling observed in more mature pups on the maternal nipple.

Background: The preweanling period in the rat is characterized by acceptance of substantial amounts of ethanol and susceptibility to its reinforcing effects. It has been unclear, however, whether the neurobiological basis of ethanol reinforcement properties at this age is in ethanol's olfactory, gustatory, or pharmacological effects., Methods: The effectiveness of intraperitoneal (ip) ethanol as a reinforcer for newborn (3-hr-old) rats was tested toward separation of the orosensory and pharmacological sources of ethanol reinforcement. Responsiveness to a test nipple by pups given such pairings was compared with that of pups given unpaired presentations of the nipple and ethanol., Results: Reinforcement was assessed in terms of response to a surrogate nipple 1 hr after a single pairing of a similar nipple providing water (conditioned stimulus) and ip injection of ethanol (0.125, 0.25, 0.50, or 0.75 g/kg; unconditioned stimulus). Significant effects of ethanol reinforcement occurred with the lower doses (0.125 and 0.25 g/kg); higher doses of ethanol (0.50 and 0.75 g/kg) had no significant reinforcement effect. A second experiment determined that for conditioning with ip ethanol as the unconditioned stimulus, a conditioned stimulus consisting of only ingesting water or only suckling on an empty nipple also yielded significant reinforcing effects of ethanol, although with less strength than their combination. Both reinforcing doses of ethanol, 0.125 and 0.25 g/kg, yielded detectable concentrations of ethanol in the blood 5 min after injection, which were sustained at a significantly lower level 60 min after administration., Conclusions: These data indicate that aside from possible, and likely weak, hematogenic sources of gustatory and olfactory attributes of ethanol, the basis of ethanol's reinforcement effect in neonatal rats is primarily pharmacological. For the pharmacological effects of ethanol to be reinforcing for the neonatal rat, concurrent appetitive activity on a nipple providing a fluid may be necessary for a substantial effect with this paradigm.

Between 1993 and 2002, 41 operations were performed for formation of a vascular access (VA) to conduct hemodialysis using vascular transplants: autogenous veins (8 cases) and PTFE allografts (33 cases). Experience gained with the use of autogenous veins and PTFE allografts for creation of a permanent VA to carry out hemodialysis was summarized and analyzed. An attempt was made to explain the causes of thrombosis of autogenous veins transplanted and allo-vessels implanted on the basis of the new general theory of circulation. The technical procedures accomplished during operations aimed at the prolongation of the time of VA functioning were offered and substantiated.

An olfactory conditioning paradigm tested whether newborn rats can acquire a conditioned aversion to olfactory events associated with their first postnatal meal 3-5 hr after birth. Exposure to lemon odor (conditioned stimulus [CS]) paired with intraoral infusions of 0.1% quinine (unconditioned stimulus) resulted in explicit conditioning. Responsiveness to a surrogate nipple providing water in the presence of the CS was significantly lower than the 3 control conditions. The conditioning dramatically suppressed responsiveness to a surrogate nipple providing milk, which normally is expressed voraciously in terms of sustained nipple attachment and milk intake. These findings suggest that as early as 3-5 hr after birth newborn rats are capable of aversive conditioning to odors in the context of suckling behavior.

The present study examined responsiveness of newborn rats to a surrogate nipple providing fluids with basic tastes (sweet, sour, bitter and salty) and assessed the effects of this first gustatory experience on subsequent responding to the nipple itself (empty nipple) or the nipple providing water. Responsiveness (attachment to and ingestion from a surrogate nipple providing saccharin, saline, quinine or ammonium chloride) was compared with that toward a nipple providing water. Compared to water, saline and quinine significantly reduced attachment to and ingestion from the nipple, while saccharin and milk significantly increased attachment behavior. Ammonium chloride increased attachment but not ingestive behavior. Suckling experience with saline, quinine and ammonium chloride attenuated both attachment and ingestive behaviors when subjects were tested 1 h later with an empty surrogate nipple or a nipple providing water. Experience with saccharin and milk (but not water) increased both measures. The data suggest that in newborn rats, as early as a few hours after birth, mechanisms of gustatory detection have control over suckling behavior. Initial experience with the tastants available from the nipple in the first suckling episode may alter further responsiveness to the nipple itself, mediated perhaps by mechanisms of appetitive and aversive conditioning.

Responsiveness to a surrogate nipple providing water, saccharin, 5% ethanol, or 10% ethanol was tested in newborn rats naive to suckling (3-5 hr old) on Postnatal Day (P) 0 and in older neonates with regular suckling experience on P1 or P2. At all ages, pups demonstrated greater nipple attachment for saccharin or 5% ethanol than for water. Intake of saccharin and 5% ethanol was high in newborns, far exceeding that of water. At P1 and P2, pups exhibited a preference for saccharin, but not for 5% ethanol. Preexposure to a nipple providing ethanol or saccharin (but not a nipple alone or fluids alone) increased subsequent responsiveness toward an empty surrogate nipple (no fluid), both 1 hr and 24 hr after preexposure. Although, during preexposure, pups responded most positively to the nipple providing saccharin, the longest time spent on an empty nipple was observed in pups preexposed to 10% ethanol.

Background: Recent evidence suggests that human infants prefer alcohol-flavored milk when fed through a bottle. Animal models also indicate a surprising predisposition for neonatal and infant rats to voluntarily and willingly ingest ethanol. These findings suggest high susceptibility to the reinforcing properties of ethanol early in ontogeny., Methods: A surrogate nipple technique-a highly effective tool for investigation of the reinforcing properties of different fluids-was applied in the present study. Tests of ethanol reinforcement were accomplished in terms of two basic paradigms of Pavlovian conditioning. In one paradigm, the conditioned stimulus (CS) was the surrogate nipple, and in the other, the CS was a novel odor., Results: Newborn rats showed sustained attachment to the nipple providing 5% ethanol, and later reproduced this behavioral pattern toward the empty nipple (CS alone). Ingestion of ethanol yielding appetitive reinforcement was accompanied by detectable blood alcohol concentrations, with most in the range of 20-30 mg/dl. The reinforcing efficacy of ethanol was also confirmed in the classical olfactory conditioning paradigm: following pairing with intraoral ethanol infusions, the odor (CS) alone elicited sustained attachment to an empty nipple. Females showed better olfactory conditioning with low concentrations of ethanol, whereas males were effectively more conditioned to high concentrations. Although there were no reinforcing consequences of intraperitoneally injected ethanol [as an unconditioned stimulus (US)] when a neutral odor was the CS, when paired with ingestion of water from a nipple, the injection of ethanol had a reinforcing effect., Conclusions: The present series of experiments revealed ethanol reinforcement in the newborn rat. Two varieties of Pavlovian conditioning established that ethanol can serve as an effective US, and hence reinforcer, in such a way as to increase the approach and responsiveness toward stimuli paired with that US, indicating appetitive reinforcement.

The present study examined the role of endogenous activity at mu and kappa opioid receptors in attachment to and ingestion of milk from a surrogate nipple in cesarean-delivered newborn rats prior to regular suckling experience. Selective opioid antagonist drugs were injected into the cisterna magna (IC administration) or lateral ventricles (ICV administration). Blockade of endogenous activity at mu opioid receptors by IC administration of the selective antagonist CTOP reduced attachment time and markedly increased disengagements from the nipple. CTOP also increased the intensity of suckling measured as milk intake per min attached to the nipple, when milk was available from the nipple in a free-access regime, and enhanced intake when milk was infused through an intraoral cannula aside from the suckling context. The ICV administration of the selective kappa antagonist nor-BNI considerably increased latency to grasp the surrogate nipple, while time on the nipple and milk intake were decreased. The presented data suggest that populations of mu and kappa receptor-containing neurons, differentiable by the route of antagonist administration, play an important role in initiation and maintenance of suckling behavior in the newborn rat during its first encounter with the nipple and milk. The kappa opioid system is predominantly involved in the initiation of the newborn's behavior directed toward the nipple providing milk. The role of the mu opioid system seems more complicated: it transforms initial oral grasp responses into sustained attachment to the nipple and maintains the intake of milk at a certain physiological level., (Copyright 2000 John Wiley & Sons, Inc.)

The rat fetus exhibits oral grasp responses when presented with an artificial nipple in utero. Preexposure to milk produces a transient decrease in oral grasp responses. The effect of milk on oral grasping is mediated by endogenous activity in brain opioid systems. Specifically, milk triggers mu activity in rostral brain regions and kappa opioid activity in caudal brain regions to decrease oral grasping of the artificial nipple. Reexposure to the artificial nipple after it has been paired with milk during a classical conditioning trial results in a conditioned reduction in oral grasping that is evident when fetuses are reexposed to the nipple. The classically conditioned decrease in oral grasping is mediated by mu opioid activity in rostral brain regions and kappa opioid activity in caudal brain regions. Endogenous opioid systems, activated by exposure to milk and the nipple, may regulate the processing of sensory information during suckling in the rat., (Copyright 2000 John Wiley & Sons, Inc.)

Newborn rat pups tested before suckling experience attached to and ingested milk from the surrogate nipple. Time attached to the nipple and amount of milk ingested depended on the schedule of milk infusion through the nipple. More frequent milk infusions resulted in more frequent disengagements from the nipple during the test, less time attached to the nipple, and less body weight gain. The initial patterns of attachment behavior--continuous or intermittent--were reproduced later when rats were tested on the surrogate nipple. Preloading of the stomach with milk effectively altered both attachment and ingestion from the nipple, whereas preloading with the same amount of water had no effect on suckling behavior. The data suggest that newborn rats flexibly adjust their attachment behavior to peculiarities of milk delivery through the surrogate nipple and reproduce the initial attachment pattern when reexposed to the surrogate nipple.

Background: In humans, early postnatal experience with alcohol is far from rare and includes exposure to alcohol through breast milk or through the bottle to attain sedative effects (Croce, 1987). Exposure to alcohol though mother's milk alters the infant's suckling behavior. However, acute effects of alcohol on suckling behavior using animal models remain to be investigated., Methods: The present study was designed to examine the effects of neonatal alcohol exposure on attachment to a surrogate nipple and ingestion of milk in rat pups, naive both to suckling and to maternal care. Cesarean-delivered rat pups were pre-exposed to four dosages of ethanol (0, 1, 2, and 3 g/kg intragastrically) and tested 30 min after ethanol administration., Results: Suckling behavior was impaired only in pups exposed to a dosage of 3 g/kg of ethanol. Pups in this group demonstrated longer latency to attach followed by less efficient suckling--the pups maintained contact with the nipple but showed decreased ingestion of milk from it. Pups treated with 1 g/kg of ethanol showed the greatest suckling efficiency, ingesting far more milk per minute attached to the surrogate nipple than pups in all other groups. At the same time, nonevoked motor activity was significantly suppressed by all three dosages of ethanol. Blood alcohol levels showed a linear relationship with dose at 30 min postintubation., Conclusions: These findings suggest a dissociation between acute ethanol effects on suckling and overall motor activity, with suckling apparently less sensitive to suppressive and more sensitive to activating effects of ethanol.

An olfactory conditioning paradigm tested the hypothesis that newborn rats are able to learn about events associated with their first experience with milk as early as 3-5 hr after birth. Exposure to lemon odor (conditioned stimulus, [CS]) paired with intraoral milk infusions (unconditioned stimulus, [US]) resulted in strong conditioning: In the presence of the CS, sustained attachment occurred to an empty nipple as if it provided milk, whereas pups in control conditions showed little attachment. A single CS-US pairing was sufficient for strong conditioning, which was evident with a trace interval as long as 60 s. Conditioning was robust enough to promote attachment to a nipple providing saline, which is aversive to the newborn rat, and comparably strong conditioning occurred with sucrose or saccharin as the US. These findings suggest that olfactory conditioning has the potential to modify suckling behavior.

Background: Ethanol intake in the context of suckling may have distinct and potentially long-lasting consequences for further responsiveness to and acceptance of ethanol, compared to other, more indirect and less natural ways of ethanol exposure early in ontogeny., Method: Our findings presented in this paper show that a surrogate nipple technique can be used for the study of early ethanol intake in cesarean-derived rat pups tested before any suckling experience., Results: Neonatal rats attached to and voluntary ingested ethanol through the surrogate nipple as early as 4 hr after birth. Moderate concentrations of ethanol (2% and 5%, v/v) promoted substantial initial suckling behavior, including sustained attachment to the nipple. Higher concentrations (10% and 15%) were not effective in sustaining suckling. Females responded less positively to 10% ethanol than did males. High concentrations of ethanol were less effective in eliciting suckling behavior, probably due to the aversiveness of ethanol odor. However, when ethanol was presented in solution with milk, newborn pups attached to the nipple and ingested even 15% ethanol. Contamination of milk with 15% ethanol was more aversive for females than for males. Newborn rat pups demonstrated similar patterns of nipple attachment and ingestive behavior for 5% ethanol and milk. Initial experience with milk in the context of suckling did not prevent further voluntary ethanol ingestion from the same nipple; furthermore, initial exposure to 5% ethanol did not impair subsequent responsiveness to milk., Conclusions: Gender differences in responsiveness or sensitivity to ethanol can be detected in rat pups as early as a few hours after birth. The results suggest a leftward shift in the dose-response curve for females compared with males, indicating that female neonates are more sensitive or more responsive than males to ethanol. The similarity of suckling behaviors produced by moderate concentrations of ethanol and milk suggests a certain unity in their reinforcing mechanisms in the context of the first suckling episode.

Newborn rats showed mouthing, licking, and oral grasping when presented with a surrogate nipple. These responses changed after the pup expressed an oral grasp response and experienced milk at the nipple. Newborn pups that ingested milk from the surrogate nipple showed brief oral grasp responses and, when tested 1 hr later, showed sustained attachment to an empty surrogate nipple. Contact with the nipple, oral grasping of the nipple, and experience with milk altered subsequent behavioral responses to the nipple. Classical and instrumental conditioning may play a role in transforming brief oral grasp responses into longer oral grasp responses and sustained attachment to the nipple.

Caesarean-delivered rat pups tested before any suckling experience show oral grasp responses after stimulation with an artificial nipple. Manipulating the sensory stimuli present at the time of testing alters behavioral responses to the nipple. Specifically, when the nipple is warm, when pups are tested in the presence of amniotic fluid or milk odor, or when pups are tested in the presence of a conspecific, oral grasping of the artificial nipple is increased. Pups respond to the nipple with a shorter latency, show more oral grasp responses, and the individual grasp responses are longer in duration. The experiments suggest that the newborn rat pup exhibits a basic set of behaviors in response to the nipple early in development and that sensory stimuli normally present during the expression of suckling increase oral appetitive behaviors evoked by the nipple.

Localized injections of the mu antagonist CTOP into intracisternal (i.c.) or intracerebroventricular (i.c.v.) sites altered the behavior of 1-day-old rat pups during continuous exposure to an artificial nipple. Blockade of mu opioid receptors by i.c. injection decreased oral responsiveness to the nipple, while blockade of receptors by i.c.v. injection of CTOP increased oral responsiveness. The injection of CTOP into the i.c. site produced a transient reduction in body weight gain in pups suckling from their mother, while injection into the i.c.v. site had no effect. When cesarean-delivered pups were tested prior to suckling, injection of CTOP into the i.c. site increased latency of the first nipple attachment and decreased total time attached to a surrogate nipple providing milk. Injection of CTOP into the i.c.v. site decreased latency to the first nipple attachment. The results indicate that there is a caudal population of opioid receptors that is involved in the initiation of suckling behavior and a rostral population that plays a role in decreasing responsiveness at the nipple.

Endogenous activity at opioid receptors affects the appetitive behavior of Caesarean-delivered rat pups during presentation of a surrogate nipple that provides milk. Blockade of opioid receptors by peripheral injection of naloxone has no effect on responses evoked by the surrogate nipple. Similarly, blockade of caudal brain opioid receptors by injection of naloxone into the cisterna magna has no effect on the pup's behavior in response to the surrogate nipple. However, blockade of rostral opioid receptors by injection of naloxone into the cerebral ventricles increases the latency to the first oral grasp response, decreases total time on the nipple, and virtually eliminates ingestion of milk from the surrogate nipple (Experiment 1). Blockade of endogenous opioid activity does not affect responses to a nipple that provides distilled water (Experiment 2) or to an empty surrogate nipple (Experiment 3). These data indicate that during the initial suckling episode endogenous opioids in rostral brain regions affect the pup's behavioral responses to the nipple. The results are consistent with the hypothesis that milk engages opioid systems during the first suckling and that endogenous opioids play a role in early suckling.

The present study reported a new technique in which pups ingested fluids from a surrogate nipple. Cesarean-delivered pups tested before suckling experience showed oral grasp responses and ingested milk from the surrogate nipple. Pups ingested equal amounts of distilled water and milk and rejected saline. After ingesting milk from the surrogate nipple, pups remained attached to an empty surrogate nipple, while pups exposed to distilled water or saline did not show sustained attachment. Brief experience with milk from an oral cannula or from a surrogate nipple elicited sustained attachment to an empty nipple. Pups ingesting milk from a surrogate nipple showed increased intake of water and saline from the nipple when tested subsequently. The surrogate nipple provides a new technique for experimental study of early suckling behavior. The results suggest that initial experiences with milk may reinforce components of early suckling behavior.

In this report we describe an apparatus and procedure that permits a newborn rat pup to ingest test fluids including milk through a surrogate nipple. The surrogate nipple represents a new testing situation for the experimental study of sensory and neurochemical controls of suckling behavior immediately after birth.

Newborn rat pups exhibit oral appetitive behaviors when presented with an artificial nipple. These behaviors include mouthing and licking movements and expression of stereotyped oral grasp response. Caesarean-delivered pups show increased responding to the nipple over the first 5 h after birth that is independent of experience with the nipple. Mimicking maternal licking by stimulating the anogenital region of the newborn rat with a soft paintbrush increases response to the nipple. Pups tested after 24 hr of normal experience respond to the artificial nipple when tested immediately after separation from the mother. However, oral grasping of the nipple is more frequent in 1-day-old pups tested 3 or 5 hr after separation from the mother. Study of behavioral responses to the artificial nipple promises to provide information about sensory and neurochemical controls of the initial suckling episode.

Pharmacological manipulation of mu opioid receptors located in rostral and caudal parts of the brain produces distinctive changes in perioral responsiveness to nipple-like tactile stimulation in the E20 rat fetus. Blockade of caudal mu opioid receptors by intracistema magna (I.C.) injection of the selective mu antagonist drug CTOP reduces appetitive responses directed toward the artificial nipple. In contrast, blockade of mu opioid receptors in the rostral part of the brain by intracerebroventricular (I.C.V.) administration of CTOP increases fetal responsiveness to perioral cutaneous stimulation including oral capture and grasping of the artificial nipple. This pattern of the results suggests that there are at least two functionally different neuronal populations of mu opioid receptor-containing neurons that are involved in the regulation of the perioral responsiveness in the E20 rat fetus. The caudal part of this mu opioid system increases perioral responsiveness while the rostral part of the system decreases responsiveness to nipple-like perioral stimulation. These findings suggest the possibility that mu opioid systems may play a functional role in regulating neonatal behavior at the nipple.

In the article a problem of the flow near of elastic surface body whalelike is considered. The opportunity appearance of the flutter on a surface body is shown. Additional capacity, necessary dolphin is designed at navigation in case of occurrence the flutter. It is shown, that this capacity makes about 26% of limiting capacity, output dolphin. Number Relcr = 4,4.10(6) transition to flutter's mode of the flow the body of the dolphin is found. It is discussed evolutionary formed the mechanism of antiflutter stabilization of the body.

A single paired presentation of the artificial nipple and milk results in classical conditioning of changes in perioral responsiveness in the E20 rat fetus. This classical conditioning is evidenced by a reduction in responding to perioral tactile stimulation. The results of Experiment 1 confirmed the specificity of milk as an unconditioned stimulus to support classical conditioning. Experiment 2 demonstrated that single-trial classical conditioning with the artificial nipple CS and milk US was possible with a delay of 30 s between nipple and milk presentations. Further, measurements of fetal motor behavior during the delay between CS and US presentations indicated that a single 15-s presentation of the artificial nipple increased movements of the mouth for 30 s after removal of the artificial nipple. Experiment 3 demonstrated that three exposures to the artificial nipple prolonged the expression of mouthing for up to 120 s and made possible single trial classical conditioning with a delay of 120 s between CS and US presentations. The capacity of the fetal CNS to maintain a "behavioral trace" for an ecologically important stimulus, such as the nipple, could have adaptive significance in the early development of motivated behavior.

Pharmacological manipulation of V1 receptors in rostral and caudal brain regions alters perioral responsiveness in the E20 rat fetus. Blockade of caudal V1 receptors or activation of rostral V1 receptors reduces fetal responsiveness to perioral cutaneous stimulation. Activation of caudal V1 receptors or blockade of rostral V1 receptors increases fetal responsiveness to perioral stimulation, including oral capture and grasping of an artificial nipple. These results suggest that V1 receptor-containing neurons regulate perioral responsiveness in the E20 rat fetus and that the 2 populations of neurons exhibit functional differences. The caudal part of the arginine8-vasopressin (AVP) system increases whereas the rostral part decreases responsiveness to different types of perioral stimuli. The neuropeptide AVP may affect suckling behavior immediately after birth by regulating perioral sensory responsiveness.

Administration of arginine-vasopressin (AVP) into the cisterna magna (IC injection) of the E20 rat fetus increases motor activity and promotes expression of rare patterns of behavior including mouthing, licking, and facial wiping. These effects are mediated by V1 receptors in the brain stem and spinal cord. In this study, AVP-induced changes in motor behavior were measured to characterize interactions within the AVP system and between the AVP and mu-opioid systems in the fetal rat. Injection of AVP into the brain hemispheres (IH injection) diminished the effects of an IC injection of AVP. AVP effects were potentiated by blockade of hemispheric V1 receptors, suggesting that hemispheric V1 receptors inhibit V1 receptor-containing neurons in the brain stem and spinal cord. Intracisternal injection of the mu agonist DAGO suppressed the effects of AVP whereas blockade of mu-opioid receptors in the brain stem and spinal cord with CTOP and activation of mu receptors in the hemispheres with DAGO potentiated the behavioral effects of AVP. The behavioral effects of AVP are mediated by V1 receptors in the brain stem and spinal cord and may be under the inhibitory control of a mu-opioid system localized at the same level of the brain. Facilitation of AVP effects following IH injection of DAGO may involve an inhibition of the inhibitory effects of V1 receptor-containing neurons located in the hemispheres. Interactions between mu-opioid and AVP systems in the caudal and rostral portions of the fetal brain may be based on a common principle.

The choice of a forelimb by a rat within two months after the damage of the left motor cortex (the right motor cortex remaining intact) depended on the degree of recovery of the injured forelimb. There was no such correlation when the right hemisphere was damaged. Distinctions in the course of recovery after the left- and right-hemisphere injury were most pronounced in the ambidextrous rats. Under free choice conditions within two months after the injury the "handed" rats predominantly chose the initially preferred ("damaged") forelimb, while ambidextrous rats preferred to use both forelimbs.

This study examined the reinforcing properties of dynorphin A (1-13) in a single-trial classical conditioning paradigm in the E20 rat fetus. Injection of dynorphin into the cisterna magna increased fetal motor activity and reduced facial wiping in a test of perioral cutaneous responsiveness. Dynorphin was effective as an unconditioned stimulus (US) in a classical conditioning paradigm using an artificial nipple conditioned stimulus (CS) and dynorphin A (1-13) US. The association between CS and US was dependent on activity in the kappa opioid system. Re-exposure to the artificial nipple CS after a single pairing of the nipple with dynorphin resulted in conditioned activation of the kappa opioid system. Dynorphin A (1-13) functions as a reinforcer for classical conditioning in the rat fetus after intracisternal or intrahemispheric injection, with the conditioned response depending on route of administration and site of injection.

It was shown that unilateral lesions of the left and right sensorimotor cortex in male Wistar rats led to similar deficit in manipulatory ability to perform the reaching task. Recovery rate depended on the side of lesion, i.e., damage of the right hemisphere was compensated sooner than that of the left one. This difference was significant in ambidextrous rats while in sinistrals and dextrals it was not pronounced.

60 mixed-bred male white rats were trained to reach food in a horizontal tube with a forepaw. In the second test access to the tube was limited by a partition so that the left-handed rats were forced to use the right forepaw and the right-handed animals the left one. While the right-handed rats successfully changed for the unpreferred left limb the left-handed animals had problems in using the right forepaw. They were manifested in 1) longer time which it took for beginning manipulation with the unpreferred limb; 2) lower rate of manipulation; 3) smaller number of animals which succeeded in switching to the unpreferred limb; 4) higher number of attempts to use the preferred limb in the left-handed rats as compared with the right-handed ones. The authors suppose that distinctions in ability of rats to shift manipulatory reaction to the unpreferred forepaw result from different lability of inhibitory processes in the left and right hemispheres. In other words, ability of the right hemisphere to inhibit the program of manipulation with the dominant left paw (left-handed rats) is lower than that of the left hemisphere to inhibit the movement of the right forelimb (right-handed rats).

Partial sensory and complete intraspecies isolation of rats leads to a state of hypersensitivity of the dophamine presynaptic receptors of the mesocorticolimbic system of the brain.

The dopamine D1 agonist SKF-38393 and the D1 antagonist SCH-23390 were administered into the left or right cerebral hemisphere of the rat fetus on E21 of gestation. Intrahemispheric (IH) injection of the agonist promoted a large-magnitude increase in fetal motor behavior, which involved movements of the head, limbs, and body trunk. Although no lateral asymmetries were evident in left or right injections of the agonist, IH injection of the antagonist into the fetus's left hemisphere produced more pronounced effects on oral behavior, including mouth, lick, and facial wipe movements. Administration of SCH-23390 into the same hemisphere as SKF-38393 was effective in reversing the behavioral effects of the agonist, with left IH injections showing more immediate and complete blockade of agonist-induced behavioral activation. These data provide evidence for functional asymmetries in D1 receptors of the dopamine system in the term rat fetus.

The kappa opioid agonist U50,488 was administered to E21 rat fetuses via intracisternal (IC), intrahemispheric (IH), or intrathecal (IT) injection. The IC administration of U50,488 promoted a threefold increase in motor activity, which was predominated by movements of caudal regions of the body (rearlimbs, body trunk, and tail). The agonist effect was reversed by IC administration of the selective kappa opioid antagonist nor-binaltorphimine. The IH injection of U50,488 had little effect on fetal behavior, but IT injection resulted in pronounced increases in fetal activity, including rearlimb, trunk, and tail movements. The IT administration of nor-binaltorphimine blocked U50,488 effects, whereas IH injection of the antagonist had little influence on fetal behavior. These findings suggest that kappa opioid receptors located in the spinal cord may play a role in the regulation of fetal motor behavior.

The dopamine D1 agonist SKF-38393 and the D1 antagonist SCH-23390 were administered into the central nervous system of the E21 rat fetus via intracisternal (IC) injection. IC injection of SKF-38393 promoted a dose-dependent increase in fetal motor activity, principally including movements of the forelimbs, head, and body trunk. IC injection of SCH-23390 did not affect overall activity, but selectively suppressed forelimb, rearlimb, and head movements and promoted an increase in mouthing, licking, and facial wiping. Administration of SCH-23390 after IC injection of SKF-38393 was effective in completely reversing the behavioral effects of the D1 agonist. These findings suggest that central manipulation of dopamine D1 receptors can have direct and potent behavioral effects in the term rat fetus.

Arginine8 vasopressin (AVP) was administered to rat fetuses on Embryonic Day 20 via intracisternal (IC), intrahemispheric (IH), or intrathecal (IT) injection. The IC administration of AVP promoted a 4-fold increase in motor activity, including the uncommon patterns of mouthing, licking, and facial wiping. The IH injection of AVP had little effect on fetal behavior, but IT injection resulted in pronounced increases in fetal activity, including mouthing, licking, and wiping. The IT administration of a V1 antagonist blocked AVP effects, whereas IH injection potentiated AVP-induced changes in fetal behavior. The IC blockade of V1 receptors suppressed facial wiping to a chemosensory fluid (lemon) and reduced oral grasping of an artificial nipple, whereas IH injection of the V1 antagonist promoted facial wiping responses and increased grasping of the nipple. These data suggest that AVP may play a role in the development of responsiveness to stimuli encountered in the context of suckling.

Intraoral infusion of milk to the rat fetus promotes opioid activity that results in reduced responsiveness in a behavioral bioassay involving perioral cutaneous stimulation. Intracisternal administration of cFP-AAF-pAB, an inhibitor of endopeptidase 24.15, prolonged the opioid activity induced by milk infusion. Treatment with the selective kappa opioid antagonist nor-binaltorphimine blocked the effect of cFP-AAF-pAB on milk-induced opioid activity, but treatment with the mu antagonist CTOP or the delta antagonist naltrindole did not. These findings imply that milk may exert its effect on fetal behavior by increasing levels of dynorphin in the fetal central nervous system.

We studied the influence of social isolation at the age of 2 months on zoosocial behaviour of mixed-bred male rats with different paw preference. Paw preference was determined in the test of reaching for food in the horizontal tube. The level of aggression but not sociability was found to increase significantly in dextral and ambidextrous late isolants. In sinistrals the increase of sociability but not aggression was observed. Analysis of probabilistic ethological structure of aggressive behaviour showed its validity and revealed the appearance of pathological aggression as a result of isolation in all groups of animals. Being connected with a disfunction of the regulating role of the right brain hemisphere this feature of aggressive behaviour is most pronounced in dextrals and ambidextrals.

The present study is devoted to a brief exposition of the results of investigations of the central mechanisms of the reinforcing properties of emotions that were carried out in the I.P. Pavlov Physiology Department of the Institute of Experimental Medicine in recent years, and to an attempt to outline the prospects for further developments in this sphere of brain physiology which is vital for conditioned reflex theory.

Peculiarities of local instrumental conditioning were studied in male and female rats brought up under the conditions of intraspecific isolation and in group. Early intraspecific isolation was found to cause a failure of the local instrumental conditioning in male rats but not in females. Right-handed and ambidextrous males brought up in isolation were shown to adapt to a new situation and to form a motor habit slower than the animals brought up in group. This occurred due to an increase of emotional reactivity of isolants. The early intraspecific isolation did not influence the velocity of the motor habit formation in males with motor dominance of the right hemisphere. In male and female rats was revealed the different sensitivity of the brain to a deficit of biologically significant influences in early ontogeny.

It was found that intraspecific behaviour of male rats having been transformed in consequence of breeding under the conditions of social isolation could be modified afterwards by an experience of social contacts. Long-term keeping the isolatedly bred rats with their mates in adulthood decreases the level of intraspecific sociability but does not affect the relatively high level of aggression of the animals under study. On the contrary, the short-term periodic social contacts with the mates in a situation of competition for water decrease only the level of aggression but not that of intraspecific sociability. However, in any case the transformations of the species-typical ritual of aggressive behaviour in consequence of early isolation are steady and are not corrected by later social contacts.

The conceptual basis of the present study is an idea on systemic interdependence of neurobiological phenomena (at any level of their occurrence, including the integral behavioural level). Characteristic peculiarities of probable organization of natural behavioural activity of Java monkeys (M. irus) kept in cages in monosexual groups were studied by recording ethograms with subsequent computer analysis. By ranging probabilities of transitions between separate behavioural acts and classifying them by motivational categories, were described the probable etiological structures of individual behaviour and intraspecific interaction in a group. Only in case of intraspecific interaction these behavioural structures were characterized by a high variability of the probability of their occurrence in different observations. The data obtained were considered from the position of biological significance of the probabilities of transitions between separate specific behavioural patterns in the organization of the whole behavioural activity.