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At least 649 records · Page 36Linked to original sources
PubMed1999

Central vasotocin-immunoreactive system in a male passerine bird (Junco hyemalis).

Previous investigations have identified regions of the avian brain that contain immunoreactive vasotocinergic (VT-ir) cell bodies and fibers. These studies exclusively used domesticated species, and the relevance of the findings for free-living birds has not been established. The present study used immunocytochemistry to determine the neuroanatomical distribution of the VT-ir system in the brain of a well-studied male passerine bird (dark-eyed junco, Junco hyemalis) obtained from a natural population in interior Alaska (65 degrees N, 147 degrees W). VT-ir cell bodies were observed in several brain regions (paraventricular and supraoptic nuclei, nucleus of the stria terminalis), where they have been described in other oscine species. VT-ir fibers were widespread in many brain regions and were especially abundant in the medial preoptic nucleus, the basal region of the septum, and the hypothalamic-neurohypophyseal tract. Fibers were also present in brain regions that are involved in the control of vocal behavior including the ventromedial capsular region of the nucleus robustus archistriatalis and the dorsomedial portion of the mesencephalic nucleus intercollicularis. The widespread brain distribution of VT-ir cell bodies and fibers in juncos generally resembles that of domestic birds and suggests a role for this neuropeptide in the control of reproductive behavior and physiology.

Animals↗
PubMed2003

Social influences on the arginine vasotocin system are independent of gonads in a sex-changing fish.

Many neuropeptide systems subserving sex-typical behavior are dependent on sex steroids for both their organization early in life and activation during maturity. The arginine vasopressin/vasotocin (AVP/AVT) system is strongly androgen dependent in many species and critically mediates responses to sociosexual stimuli. The bluehead wrasse is a teleost fish that exhibits a female-to-male sex change in response to social cues, and neither the development nor the maintenance of male-typical behavior depends on the presence of gonads. To examine social and gonadal inputs on the AVP/AVT system in the preoptic area (POA) of the hypothalamus, we conducted three field experiments. In the first experiment, we found that AVT mRNA abundance is higher in sex-changing females that attain social dominance and display dominant male behavior than in subordinate females, regardless of whether the dominant females were intact or ovariectomized. However, AVT-immunoreactive (IR) soma size in the gigantocellular POA (gPOA), but not in the magnocellular or parvocellular POA, increased only when females were displaying both dominant male behavior and had developed testes. In the second experiment, castration of dominant terminal-phase males had no effect on AVT mRNA abundance or any behavior we measured but did increase gPOA AVT-IR soma size compared with sham-operated controls. In the third experiment, 11-ketotestosterone implants in socially subordinate, ovariectomized females had no effect on either AVT mRNA abundance or AVT-IR soma size compared with controls. These results demonstrate that the AVT neural phenotype in the bluehead wrasse can be strongly influenced by social status, and that these social influences can be manifested independent of gonads.

Animals↗
PubMed2002

The role of arginine vasotocin in teleost fish osmoregulation.

The AVT system is a key component of the complex mechanism responsible for coordinating the response in teleost fish to hyper-osmotic challenge. The pituitary AVT store falls following transfer to SW from FW and this is accompanied by an increase in circulating AVT levels. This indicates that there has been release of AVT in response to this stimulus and the system is being up-regulated. The effect of an increase in secretion would appear to be predominantly to reduce GFR and urine production as is seen when AVT is injected into FW-adapted fish. This action is consistent with the requirements of hyper-osmotic challenge when water conservation becomes essential.

Animals↗
PubMedDate not supplied

Growth hormone (GH) release by arginin-vasotocin (AVT) given intranasally in sexually immature children.

Eighteen healthy children were given 50 micrograms synthetic AVT intranasally and samples of serum for GH, magnesium and alpha-amino-nitrogen were drawn 30, 60 and 120 minutes later. There was a significantly different mean of GH peak level (13.1 +/- 3.02 microU/ml) which occurred generally at 30 minutes. The number of GH responders (i.e. peak level greater than 15 microU/ml) was of 7/18. The means of chemical determinations elicited little though opposite changes: slight increases in magnesium and slight decrease in alpha-amino-nitrogen. In a separate day, a sleep test of 30 minutes-duration performed in the morning resulted in a significantly greater GH peak level (28.2 +/- 9.7 microU/ml) but the number of GH responders was nearly the same (6/18). The serum magnesium levels following sleep decreased slightly and unsignificantly. The involvement of serotonergic neurons in mediating GH-releasing effects of AVT is briefly discussed.

Administration, Intranasal↗