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PubMed1991

Ontogenetic and seasonal changes in immunoreactive vasotocin in the canary brain.

Using immunocytochemistry the central VT system of the canary was examined during ontogeny and throughout the season. At 4 weeks of age no VT-immunoreactive staining in the bed nucleus of the stria terminalis and lateral septum was present, but VT-containing cells and fibers were clearly visible in the nucleus paraventricularis of the hypothalamus. At 13 weeks of age a weak VT immunoreactivity appeared in the bed nucleus of the stria terminalis and lateral septum. This VT immunostaining increased progressively till at the age of 28 weeks adult levels were reached. In adulthood, cells and fibers in the lateral septum and the bed nucleus of the stria terminalis contained the highest amounts of immunoreactive VT during the breeding season, whereas during the molt, in august, a decreased VT immunostaining was noted. These seasonal changes in VT immunostaining coincided with variations in circulating testosterone level, which is high during the breeding season and low during the molt. In the ventral capsular region surrounding the nucleus robustus archistriatalis a clear VT-immunoreactive fiber pattern was demonstrated at the age of 8 and 13 weeks in both female and male canaries. Although the size of this nucleus varies during the season no seasonal changes in the VT-immunoreactive pattern surrounding the RA were detected. The data suggest that the activity of the VT system slowly increases during development. At adulthood seasonal and gonadal hormone-dependent changes occur in the limbic VT system only. The VT immunostaining associated with the nucleus robustus archistriatalis however, is resistant to seasonal and gonadal influences.

Aging↗
PubMedDate not supplied

Arginine vasotocin and aggression in rats.

Pinealectomized (PX) and sham animals were administered either AVT (1 ng/kg) or vehicle (1 ml H20). Boxing-kicking-biting episodes were significantly reduced by administration of AVT, F(1,21) = 8.09, p less than 0.009. Crawling under behavior was increased in PXH20 animals (p less than 0.05). Non-aggressive rearing was decreased by administration of AVT, F(1,21) = 4.75, p less than 0.04. These results are in agreement with previous findings that AVT lowers emotionality-arousal. Results are discussed in terms of vasotonergic effects on central monoamines.

Aggression↗
PubMed2006

Aromatase immunoreactivity in the bluehead wrasse brain, Thalassoma bifasciatum: immunolocalization and co-regionalization with arginine vasotocin and tyrosine hydroxylase.

Sex steroid hormones regulate various neural functions that control vertebrate sociosexual behavior. A number of sex steroids can be synthesized de novo in the brain, including estrogens by the enzyme aromatase. Aromatase, the neuropeptides arginine vasotocin/vasopressin, and the monoamine neurotransmitter dopamine have all been implicated in the control of male sexual and aggressive behavior in a variety of vertebrates. This study examined the expression of brain aromatase in the bluehead wrasse (Thalassoma bifasciatum), a teleost fish that exhibits socially controlled behavioral and gonadal sex change. We used immunocytochemistry (ICC) to characterize distributions of aromatase-immunoreactive (ir) cells, and to examine their relationship with AVT-ir neurons and tyrosine hydroxylase-ir (TH-ir) neurons in key sensory and integrative areas of the brain of this species. Aromatase-ir appeared to be in glial cell populations, and was found in the dorsal and ventral telencephalon, the preoptic area of the hypothalamus, and the lateral recess of the third ventricle, among other brain areas. Aromatase-ir fibers are closely associated with AVT-ir neurons throughout the preoptic area, indicating the potential for functional interactions. Aromatase-ir cell bodies and fibers were also co-regionalized with TH-ir neurons, suggesting possible interaction between the dopaminergic system and neural estrogen production. The presence of aromatase in brain regions important in the regulation of sexual and aggressive behavior suggests that local estrogen synthesis could regulate sex change through effects on signaling systems that subserve reproductive behavior and function.

Aggression↗
PubMed2006

Effect of long and short photoperiod on vasotocin neurons of paraventricular nuclei and adrenal function of water deprived Japanese quail.

The responses of magnocellular neurons of paraventricular nuclei (PVN) and changes to adrenal activity to water deprivation in Japanese quail maintained under gonado-inhibitory and stimulatory photoperiods were examined. Water deprivation of 4 days resulted in a 12% decrease in body weight of sexually regressed short day (SD, 6L:18D) quail, while the decrease was more (18%) in sexually stimulated long day (LD, 16L:8D) quail. The increase in plasma osmolality following water deprivation was also more (47%) in LD than to SD quail (36%). Under the LD condition, quail had increased numbers, sizes and immunostaining of ir-AVT neurons of PVN compared to SD condition. A significant increase in the number of ir-AVT neurons was observed following 4 days of water deprivation in both SD and LD quail compared to their respective fully hydrated controls. However, the degree of response was more under the LD compared to the SD condition suggesting that gonado-stimulatory long days increase the activity/response of the AVT system. Increased adrenal ascorbic acid content (i.e., activity) was also observed to quail of LD when compared to SD treatment. However, osmotic stress led to adrenal hypertrophy and hyperactivity of quail of both of the photoperiodic regimes. Our findings indicate that not only osmotic stress but also photo-gonadal stimulation upregulates the expression of hypothalamic AVT genes and increases the localization of ir-AVT in many neurons of PVN. The above results support the existence of a parallel adrenal-gonad relationship and increase in adrenal function during osmotic stress, which also leads to simultaneous increase in AVT system. We conclude that photo-sexual conditions alter hypothalamic vasotocinergic and adrenal activity in Japanese quail and the degree of stimulation of the two systems following osmotic stress is higher under gonado-stimulatory LD conditions.

Adrenal Glands↗
PubMed2005

A potential cardiovascular mechanism for the behavioral effects of central and peripheral arginine vasotocin.

Few studies have attempted to separate the behavior modulating actions of central and peripheral arginine vasotocin/arginine vasopressin (AVT/AVP) from their roles in the endocrine and cardiovascular stress response. This series of experiments explored the relative contributions of AVT's central and peripheral mechanisms on altering behavior while simultaneously investigating AVT's effects on the behavioral, cardiovascular, and corticosteroid responses to acute stressors in European starlings (Sturnus vulgaris). Results illustrated peripheral AVT's ability to decrease feeding, drinking, preening, and overall activity. Effects on feeding, drinking, and preening were similar after AVT injection into the lateral ventricles, but the central effects were not blocked by dPTyr(Me)AVP, a selective AVT receptor blocker. This suggests that AVT's behavioral effects may not depend solely on a receptor mediated central mechanism. However, both central and peripheral AVT attenuated heart rate independent of increased plasma corticosterone. These data suggest that AVT's behavioral effects may be modulated by a corticosterone-independent cardiovascular mechanism.

Animals↗