Showing papers in "General and Comparative Endocrinology in 1993"

TL;DR: The relative potency of several androgens to induce the male phenotype in sexually undifferentiated genotypic female chinook salmon were compared in two separate experiments and 11-KT and T showed virtually no masculinizing effect in inducingmale phenotype in these studies.

TL;DR: The magnitude of the steroid-induced immunosuppression was reduced during winter and increased again in spring, and Testosterone and cortisol administered together had a significantly greater effect than did either administered alone.

TL;DR: Methyl farnesoate stimulation of ecdysteroid secretion by Y-organs of the crab, Cancer magister, is demonstrated and the magnitude of this stimulation increased with higher concentrations of MF and increasing incubation times.

TL;DR: The hypothesis that a CRH-like peptide is involved in the central control of metamorphosis of anuran amphibians, and may act, at least in part, through stimulation of the thyroid axis, is supported.

TL;DR: It is concluded that the pituitary-adrenocortical feedback system in hares from declining populations is operating normally and that they should be able to cope with acute, short-term stressors, but that they are in poor condition and are exposed to higher levels of free cortisol than fed hares in good condition.

TL;DR: The results support hypothesized roles for androgens in male function and E2 in female function in A. melanopus, however, E2 increases lagged behind oogonial proliferation, arguing against an influence of this steroid in the initiation of female function.

TL;DR: The findings suggest that the synthesis and secretion of the two tPRLs could be independently regulated in the same cells.

TL;DR: Results are similar to those previously obtained in E. orbicularis and agree with a key role for endogenous estrogens in gonadal differentiation of reptiles with temperature-dependent sex determination (TSD).

TL;DR: Observations suggest that GTH I, but not GTH II, may regulate initial gonadal growth and development in the embryonic and larval rainbow trout.

TL;DR: Once the rapid gonadal growth phase had begun it took about 6 weeks for the testes to reach maximal size in all three populations, and initially testicular size and plasma levels of LH were similar among the four groups.

TL;DR: The results indicate that the priming pheromone acts through the hypothalamus-pituitary-gonad axis, and that anosmic males spawned as readily as intact males when paired with ovulated females.

TL;DR: Histological analysis of the ovary indicated that an important number of spawnings has occurred since the proportion of oocytes in final maturation stage was very low, and fish in the regressive phase also presented high steroid levels.

TL;DR: The results suggest that NPY may play a physiological role in the regulation of GH and GtH-II secretion in the goldfish and confirm the previous findings using hNPY.

TL;DR: Results suggest that a cyclooxygenase metabolite of AA, likely PGE2, is involved in the control of steroidogenesis in the goldfish testis and that this metabolite mediate T production through the actions of the same signaling molecule.

TL;DR: In gonad-intact goldfish, sex steroids enhance pituitary responsiveness to GnRH but basal serum GtH-II levels are maintained by a concomitant increase in DA turnover in the pituitsary.

TL;DR: GH release in common carp is regulated by somatostatin as GH release inhibitor; the mechanisms by which GnRH stimulates GH and GtH secretion are independent.

TL;DR: The study indicates that steroid hormone levels are labile in response to changes in population density, and frequency of territorial interaction, and changes in levels of plasma androgens are consistent with the "challenge" hypothesis of social regulation of territorial aggression.

TL;DR: Temperature modulates the responsiveness of the liver to E2 at stages which are independent of E2 or ER concentrations, suggesting greater efficiency or capacity for translation and or processing of the Vg protein at the higher temperature.

TL;DR: For example, in a recent study as mentioned in this paper, the gonadal levels of several gonadal steroids (testosterone, 11-ketotestosterone, androstenedione, 17β-estradiol, and estrone) were measured by RIA in the Protandrous seabass, Lates calcarifer, throughout an annual reproductive cycle.

TL;DR: The garden warbler Sylvia borin is a long-distance migrating bird that travels exclusively at night and the results show that the 24-h plasma melatonin profiles of these birds are rather robust and that locomotor activity does not depend in a simple and direct way on plasmaMelatonin levels.

TL;DR: It is suggested that cortisol could play a critical role in the hypoosmoregulation in tilapia larvae.

TL;DR: The influence of growth factors on the proliferation and differentiation of clonal-derived embryonic myoblasts and satellite cells was examined in hormonally controlled serum-free media and IGF-II was the more potent mitogen for embryonicMyoblasts.

TL;DR: Results suggest that protein kinase C may also be involved in the steroidogenic actions of GTH I and GTH II.

TL;DR: Immunolocalization of steroidogenic enzymes suggests that steroidogenesis may occur not only in Leydig cells, but also in spermatids of the Hokkaido brown bear testis prior to the mating season.

TL;DR: The increased activity of SL cells in the fish in low calcium environment suggests a hypercalcemic action as one of the functions of SL.

TL;DR: The results suggest that the stimulatory effects of bGH and hCG on aromatase activity depend upon the synthesis of new RNA and regulatory protein(s) through adenylate cyclase-cAMP-dependent mechanism(s).

TL;DR: The demonstration that 5-HT and GnRH systems are in close proximity, particularly in the olfactory bulbs and in the preoptic-anterior hypothalamic area of the croaker brain, suggests that the two systems may interact in these regions of the teleostean brain to control several reproductive functions including spawning behavior and gonadotropin release.

TL;DR: The aim of this study was to localize androgen receptor (AR) in the small, preovulatory and postovulatory follicles of laying hens by an immunocytochemical method and Western blot analysis.

TL;DR: The results indicate that SS-14 and sSS-25 are important regulators of carbohydrate and lipid metabolism in rainbow trout and that modulation of metabolic activity by these peptides may be accomplished, in part, by alterations in insulin and glucagon levels circulating in the plasma.

TL;DR: Sea bream pituitary contains immunoreactive PTHrP, which appears to be released into medium during in vitro incubation and which may be a significant source of plasma immunodetectable PTHRP in vivo.