[Reverse turns and sense of angle in the orientation of Lithobius forficatus L. II: The outer and inner reference points].
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We tested the hypothesis that genes encoded on the sex chromosomes play a direct role in sexual differentiation of brain and behavior. We used mice in which the testis-determining gene (Sry) was moved from the Y chromosome to an autosome (by deletion of Sry from the Y and subsequent insertion of an Sry transgene onto an autosome), so that the determination of testis development occurred independently of the complement of X or Y chromosomes. We compared XX and XY mice with ovaries (females) and XX and XY mice with testes (males). These comparisons allowed us to assess the effect of sex chromosome complement (XX vs XY) independent of gonadal status (testes vs ovaries) on sexually dimorphic neural and behavioral phenotypes. The phenotypes included measures of male copulatory behavior, social exploration behavior, and sexually dimorphic neuroanatomical structures in the septum, hypothalamus, and lumbar spinal cord. Most of the sexually dimorphic phenotypes correlated with the presence of ovaries or testes and therefore reflect the hormonal output of the gonads. We found, however, that both male and female mice with XY sex chromosomes were more masculine than XX mice in the density of vasopressin-immunoreactive fibers in the lateral septum. Moreover, two male groups differing only in the form of their Sry gene showed differences in behavior. The results show that sex chromosome genes contribute directly to the development of a sex difference in the brain.
Multiparameter scale for evaluation of anxiety-phobic state in rats reveals significant enhancement of anxiety in rat pups after 6-week isolation (beginning from the 21st day from birth) as compared to grouped controls of the same litter: the locomotion and exploration that appear in test areas are suppressed, and species-specific fear reactions are enhanced. These changes considered as signs of situational anxiety are not eliminated by 2.5-month keeping in groups. Nevertheless, they are not correlated with parameters of the acoustic startle reflex that (by the data of literature) is thought to be related with fear and anxiety. On the basis of the discrepancy it is proposed that state of anxiety is selective. This suggestion is confirmed by individual behavioral variations characterized by a combination of a low level of situational anxiety and a high level of acoustic anxiety observed in both experimental and control groups. These variations may explain the existence of atypical "emotional resonance"-like behavior according to P.V. Simonov. Attention is given to selectively enhanced acoustic startle reflex in the group of active control as an evidence for critical importance of any manipulations with social context in early ontogeny.
Prenatal alprazolam (APZ) treatment in 0.1 and 0.2 mg/kg/day doses during 13-20 days of gestation induced significant increase in open-field ambulation, rearings, self-grooming and faecal pellets in rat offspring. Prenatal APZ treated rats displayed significantly increased anxiogenic behaviour on elevated plus maze (spent less time on open arms, more time on enclosed arms and made less number of entries on open arms) and increased anxiogenecity on elevated zero maz e(APZ treated rats spent less time on open arms and made less number of head dips and stretched attend postures in comparison to control rat offspring). The results indicate persistent behavioural alterations in the rat offspring after prenatal exposure to APZ.
Muscimol, a selective agonist of GABA-A receptors, causes changes in behavioral activity. Hypoxia interferes with the GABAergic system and with the functions of GABA-A receptors. We used muscimol in Wistar rats to estimate its influence on locomotor activity in the open field test as well as on the processes of consolidation and retrieval, evaluated in the test of passive conditioned reflexes. Anxiolytic activity was examined in the elevated "plus" maze in physiological state and after hypoxia-induced amnesia. Following intraperitoneal administration of muscimol (1 mg/kg, ip), the animals showed a decrease in motility, in retrieval of skill reflexes and in a number of entries into open and closed arms in the elevated plus "maze". In animals exposed to hypoxia, we observed reduced motility in the open field, inhibition of retrieval and consolidation of passive conditioned reflexes, shortened time of sojourn in open arms and decreased number of entries into open and closed arms. In the group of animals which underwent hypoxia and then received muscimol, we observed no effect of hypoxia on muscimol activity in the open field test, except rearing when muscimol action was significantly reduced. Muscimol improved consolidation but not retrieval in comparison with the hypoxic saline-treated group of rats. In the elevated "plus" maze test, treatment of rats with muscimol after hypoxia significantly prolonged the time spent in open arms and increased the number of entries into open arms, while shortened the time spent in closed arms. In conclusion, muscimol in hypoxia-exposed group of rats exerted beneficial effect on consolidation in passive avoidance situation and exerted anxiolytic activity. Changes in the activity of muscimol under hypoxia may have significant clinical implications.
Gene-targeted mice lacking the AMPA receptor subunit glutamate receptor-A (GluRA) (GluR1) and wild-type controls were compared on a radial-maze task in which the same three of six arms were always baited, but in which the rewards of milk were not replaced within a trial. This procedure allowed not only a within-subjects but also a within-trials assessment of both spatial working memory (WM) and reference memory (RM) in GluRA-/- mice, using identical spatial cues. In experiment 1, the GluRA-/- mice made more WM and RM errors during task acquisition. However, separate groups of GluRA-/- and wild-type mice (experiment 2) acquired a purely RM version of the task at a similar rate, using a paradigm with which it was not possible to make WM errors (doors prevented mice from re-entering an arm that they had already visited on that trial). In contrast, mice with hippocampal lesions were dramatically impaired. These results are consistent with the possibility that the WM impairment in the GluRA-/- mice during experiment 1 produced interference that disrupted RM acquisition. A WM component was therefore introduced after RM acquisition in experiment 2 (i.e., the mice were no longer prevented from re-entering a previously visited arm). The GluRA-/- mice now made considerably more WM errors than did wild-type mice, but simultaneously, RM was only mildly and transiently impaired. These experiments provide additional evidence of a selective spatial WM deficit coexisting with intact spatial RM acquisition in GluRA-/- mice, suggesting that different neuronal mechanisms within the hippocampus may support these different kinds of information processing.
OBJECTIVE: To study the role of different antidepressants on exploration, spontaneous motor activity and isolation-induced aggressiveness in mice, further to discuss different mechanisms of their anti-aggression. METHODS: With an aggressive model induced by isolation housing in mice, antagonism of different antidepressants against isolation-induced aggression was evaluated. In the group-housed mice given the same treatment as aggressive test, exploration and spontaneous motor activity were measured. RESULTS: (1) Mianserin (0.5-5 mg/kg-1), buspirone (2.5-10 mg.kg-1) and meclobemide (2.5-10 mg.kg-1) significantly inhibited the exploration in the group-housed mice, but not fluoxetine (2.5-10 mg.kg-1), imipramine (2.5-10 mg.kg-1) and DOI (0.5-2 mg.kg-1); (2) Both mianserin and buspirone, but not fluoxetine, imipramine, meclobemide and DOI, obviously reduced spontaneous motor activity; (3) Fluoxetine, miaserin, imipramine and buspirone significantly and dose-dependently antagonized isolation-induced aggressive behavior, whereas meclobemide failed to attenuate aggression. DOI dual-regulated aggressiveness in isolation mice. CONCLUSION: Our findings suggest that the effects of fluoxetine, mianserin, buspirone, imipramine, meclobemide and DOI on exploration, spontaneous motor activity and isolation-induced aggression in mice are different, which may involve different pharmacological mechanisms underlying their anti-aggression in isolation mice. 5-HT1A and 5-HT2A/2C receptors may mediate isolation-induced aggressive behavior in mice. The involvement of 5-HT receptor subtypes needs further clarification.
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Research indicates that three primary components play a role in the picky eating phenomenon: development, personal preferences, and the family. Picky eating is an aspect of child development. Children will develop their own preferences when given the appropriate tools to do so. Parents are their children's greatest role models. An understanding of these concepts can help guide the primary care provider in making appropriate recommendations to parents to improve their toddlers' eating behaviors.
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Behavioral effects of low, sub-pyrogenic doses of IL-lbeta were investigated in rats. It was shown that increasing of anxiety level started to occur as of the 5th day of the administration course. The data obtained suggest importance of pro-inflammatory cytokines in pathogenesis of psycho-emotional disorders.
The amygdala is a critical component of the neuroanatomical stress circuit. It plays a role in the generation of responses to emotional stimuli. The central (CeA) and medial (MeA) amygdaloid nuclei are implicated in activation of the hypothalamic-pituitary-adrenocortical (HPA) axis. The immunoreactivity (-ir) of c-Fos, NGF and its receptor, TrkA, following acute and chronic open-field stress were studied in the CeA and MeA nuclei of the amygdala. The material consisted of 21 male adult rats divided into three groups: non-stressed (control) animals, rats exposed to acute (once only lasting 15 min) and chronic (15 min daily over 21 days) aversive stimulation (open-field exposure). The brains were stained with the use of immunohistochemical methods for c-Fos, NGF or TrkA. In the control rats c-Fos-, TrkA- and NGF-ir cells were observed in the nuclei studied, but the quantity varied, being moderate or high (immunoreactive to TrkA and NGF) or low (immunoreactive to c-Fos). In the animals exposed to acute open-field stress the number of c-Fos-ir, NGF-ir and TrkA-ir cells in the nuclei under examination was differentiated but higher than that in the control animals. In the animals exposed to chronic open-field stress the number of c-Fos-ir cells in the nuclei studied was similar and was smaller than those in animals exposed to acute stress. The number of TrkA-ir neurons was also lower in comparison to that in animals exposed to acute stress. However, no significant differences in the number of NGF-ir cells were observed between the groups exposed to acute and chronic stress. Diverse expression of c-Fos protein following both acute and chronic stress stimulation may prove the functional heterogeneity of the amygdaloid nuclei investigated. The decrease observed in both c-Fos- and TrkA-ir in MeA (only TrkA in CeA) of animals exposed to chronic stress may indicate the phenomenon of habituation.
The effects of differential experience over most of the adult lifespan of mice were examined utilizing longitudinal designs. Repeated experience with nest building was contrasted with one-time only experience at various age levels from 4 to 24 months of age. The results suggest that the presence or absence of repeated exposure to nest building opportunities affects stability of nest building, while open field activity remains stable regardless of experience and vitality declines regardless of experience. Because nest building at maturation is not influenced by prior experience, the effect of differential experience during the course of aging is not interpreted as a reflection of differential initial acquisition of the behavior. Rather, performance differences are interpreted as providing evidence for the differential maintenance of neural integrity of the underlying mediator for the behavior. The discrepancy among the patterns of change for nest building, open field activity, and performance on the tightrope test is interpreted as reflecting differences in the relative importance of deterioration of the underlying neural mediators in comparison with decreases in muscular strength and flexibility. Implications for design issues in animal research in aging are discussed.
Our earlier experiments have shown that the facilitating action of angiotensin II (AII) on recall of passive avoidance is mediated by dopaminergic systems. In an attempt to find the site of action of AII on memory in the brain, bilateral lesions of the two structures belonging to the limbic system, receiving efferentation from A 10 dopaminergic neurons, were made in 32 male rats before behavioral testing of the influence of intracerebroventricular AII injection on recall in a passive avoidance situation. 32 additional rats served as sham operated controls. Bilateral lesions to the dentate gyrus of the hippocampus and olfactory tubercle did not significantly change the facilitating effect of AII on recall. The results may suggest that dopaminergic projections from A 10 neurons of the ventral tegmental area to the dentate gyrus and olfactory tubercle are not responsible for the enhancing effect of AII on recall of passive avoidance.
A method is described, in which small laboratory animals are freely moving in the field of analogous capacitive sensors. The electrical signals induced by animal movements which, according to amplitude and polarity, contain informations on intensity and direction of movements are conveyed to a classification device and classified according to well-defined classes. By measuring during a fixed time (e.g. 10 min) or for a previously determined number of signals (e.g. 2000) a distribution of class frequencies, the movement profile, is obtained. Parameters of movement profile of mice in the orientation phase and factors of influence are reported on. The method allows the continuously automatic registration of movement profiles.
In domesticated at the age from 30-th to 60-th days foxes an intensification of orienting-investigating behaviour takes place in unknown situation. Cortisol level is not changed. In foxes, selected for aggressive behaviour towards man, at 30 days age the orienting-investigating behaviour is also observed, and hormone concentration does not differ from that in domesticated fox-cubs. In aggressive cubs of 45 days a defensive behaviour develops and cortisol content in blood significantly increases. Participation is discussed of adrenal cortex hormones in manifestation of defensive reactions and mechanisms of restriction of sensitive period of socialization.
Long term exposure of adult male Sprague Dawley rats to rewarding brain stimulation produced alterations in open field behavior in comparison to nonstimulated controls. Initial activity was increased while movement latency was decreased for the experimental animals. Grooming and defecation were essentially unchanged by stimulation. These findings suggest a selective and tonic influence of brain stimulation upon exploration.