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At least 19 recordsLinked to original sources
PubMed1979

Variations in plasma prolactin, thyroid hormones, gonadal steroids and growth hormone in turkeys during the induction of egg laying and moult by different photoperiods.

1. Concentrations of prolactin, growth hormone, testosterone, progesterone, thyroxine and triiodothyronine were measured in the blood plasma of female turkeys during successive periods of egg laying, a decline in lay, a moult induced by a short photoperiod (6 light: 18 dark) and a resumption of egg laying induced by a long photoperiod (16L:8D). 2. Concentrations of prolactin, growth hormone, testosterone and progesterone were higher in laying birds than in birds which were moulting or not laying. 3. The concentration of testosterone, but not of the other hormones studied, increased significantly during the period of profuse moult. 4. Concentrations of the thyroid hormones did not change with the varying physiological condition of the birds. However, the concentration of thyroxine was depressed by the long photoperiod.

Animals↗
PubMed1975

Relation of the pituitary gland to gonadal hormone effects on the adrenocortical 11beta-hydroxylase system in rats.

Studies were conducted to further examine the mechanisms responsible for gonadal hormone effects on the rat adrenocortical 11beta-hydroxylase system. Despite higher concentrations of cytochrome P-450 and larger 11-deoxycorticosterone (DOC)-induced difference spectra in adrenal mitochondria from females than males, no sex difference in 11beta-hydroxylase activity was observed. The pregnenolone-induced difference spectrum, indicative of cholesterol binding to cytochrome P-450, also was similar in males and females. Testosterone administration to castrated males lowered both 11beta-hydroxylase activity and mitochondrial cytochrome P-450 content. Estradiol produced the opposite effects in castrated females. However, when given to ACTH-replaced hypophysectomized rats, neither testosterone nor estradiol affected cytochrome P-450 levels or the rate of 11beta-hydroxylation. These observations, taken with the known effects of estradiol and testosterone on ACTH secretion in rats and the effects of ACTH on 11beta-hydroxylation, indicate that gonadal hormone effects on the 11beta-hydroxylase system are mediated by ACTH.

Adrenal Glands↗
PubMed1979

Requirement of the pituitary gland for gonadal hormone effects on hepatic drug metabolism in rats.

Previous studies have demonstrated an important role for the pituitary gland in the regulation of hepatic drug and steroid metabolism. The present studies were carried out to determine the relationship between the pituitary gland and the actions of gonadal hormones on hepatic drug metabolism in rats. Testosterone administration to castrated male rats increased hepatic microsomal cytochrome P-450 concentrations and enhanced the rates of ethylmorphine demethylation and benzo(a)pyrene hydroxylation. Estradiol treatment, on the other hand, lowered cytochrome P-450 levels and decreased the rates of aniline, ethylmorphine and benzo(a)pyrene metabolism in orchiectomized rats. However, when given to hypophysectomized male rats, neither testosterone nor estradiol affected cytochrome P-450 levels or enzyme activities. Similarly, 5alpha-dihydrotestosterone administration increased hepatic drug metabolism only in the presence of the pituitary gland. The effects of both testosterone and estradiol were fully demonstrable in the absence of the thyroid or adrenal glands, excluding the need for either organ. The results indicate an absolute dependence on the pituitary gland for gonadal hormone (testosterone and estradiol) actions on hepatic mixed-function oxidases.

Adrenalectomy↗
PubMed1979

The interaction between dietary calcium and gonadal hormones in their effect on plasma calcium, bone, 25-hydroxycholecalciferol-1-hydroxylase, and duodenal calcium-binding protein, measured by a radioimmunoassay in chicks.

Male chicks, fed low, normal, or high calcium- and cholecalciferol-containing diets for 14 days, were given three combined injections of 17 beta-estradiol and testosterone (7 and 2.4 mg/kg/dose, respectively) or the vehicle alone, at 3-day intervals. The hormonal treatment resulted in increased plasma calcium and medullary bone calcium concentrations, independently of the dietary calcium intake. Kidney 25-hydroxycholecalciferol-1-hydroxylase and duodenal calcium-binding protein were increased in response to gonadal hormones. The magnitude of this response markedly diminished with increased calcium intake and almost completely disappeared in chicks fed the high calcium diet. The results suggest that the increases in plasma calcium and medullary bone formation due to gonadal hormones are independent of calcium intake while the effect of hormones on duodenal calcium-binding protein and the 25-hydroxycholecalciferol-1-hydroxylase activity appears to be mediated through the change in calcium needs due to medullary bone formation.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1979

The effect of adrenal and gonadal hormones on vascular permeability in rat skin.

The effect of adrenal and gonadal hormones on vascular permeability induced by intradermal injection of prostaglandins (PGs) E1, F2alfa, arachidonic acid and compound 48/80 have been examined in the rate. PGE1, arachidonic acid and compound 48/80 produced an increase in local vascular permeability. PGF2alfa decreased the action of these vasoactive agents, when it was injected in a mixture intradermally with PGE1, arachidonic acid and compound 48/80. Vasoactive response induced by PGE1, arachidonic acid and compound 48/80 was inhibited by the removal of adrenals and testes, and it was restored to normal by injection either of cortisol, deoxycorticosterone (DOC) or testosterone. In adrenalectomized rats, no change was observed in the inhibition of vascular permeability elicited by PGF2alfa response to compound 48/80. The blocking effect of PGF2alfa on vascular permeability evoked by PGE1 and arachidonic acid showed a considerable decrease. After orchidectomy the inhibitory effect of PGF2alfa on the vascular permeability induced by arachidonic acid and compound 48/80 was completely blocked, while in the case of PGE1 the inhibition was partial. Testosterone treatment restored the anti-inflammatory effect of PGF2alfa against compound 48/80. Ovariectomy was without any effect on vascular response.

Animals↗
PubMed1978

Effects of gonadal hormones on the hypothalamic multi-unit response to glucose and saline in the rat.

The role of gonadal hormones in modulating the hypothalamic multi-unit activity (MUA) response to glucose and saline was studied in normal and gonadectomized male and female rats. In intact male rats, unlike intact females, all hypothalamic placements showed either an increase or a decrease in MUA following an injection of glucose. Gonadectomy alone did not produce a significant change in the pattern of hypothalamic response to glucose. Daily injections of estradiol-17beta resulted in a significant increase in the number of hypothalamic sites that did not show a glucose-induced change in MUA. In general, the effects on saline tended to parallel those on glucose, although the changes were not as extensive. The results are discussed of estradiol modulation of body weight (b.w.) and of the hypothalamic responsiveness to various stimuli, including glucosse and saline injections.

Animals↗
PubMed1979

Roles of predisposing factors and gonadal hormones in the buller syndrome of feedlot steers.

In a study of the role of predisposing factors and gonadal hormones in the buller syndrome, it was found that weather, amount of space available to each steer, and entry weights of the steers were not associated with increased occurrence of bulling; however, the type and timing of administration of the hormonal implant, the number of steers in a pen, and the manner in which the steers were grouped after arrival at the feedlot were found to influence the incidence of the syndrome. Serum concentrations of estradiol and testosterone in the buller steers were found to be lower during bulling than after a short period of isolation and apparent recovery from the syndrome. It was concluded that the occurrence of bulling is related to the use of hormonal implants and certain feedlot management procedures but that it is apparently not related to increased serum estrogen or testosterone concentrations.

Animal Feed↗
PubMed1979

Sex differences in adrenocortical structure and function. V. The effects of postpubertal gonadectomy and gonadal hormone replacement on nuclear-cytoplasmic ratio, morphology and histochemistry of rat adrenal cortex.

Studies were carried out on adult rats of Wistar strain. Six weeks after postpubertal gonadectomy some of the orchiectomized rats were injected with a single dose of testosterone cypionate and ovari-ctomized rats with estradiol cypionate (17 beta-cyclopentyloproprionate esters of testosterone or estradiol). The control rats were sham operated. Investigations were carried out 8 weeks after surgery. Absolute and relative adrenal weight is lower in the male than in the female rat. Orchiectomy increases these weights while testosterone restores them to their normal level. Ovariectomy has no effect on the weight of adrenal, estradiol, however, increases the relative weight of the gland. The adrenal cortex of the adult female is wider than in the adult male rat and in female gland sudanophobic zone is lacking. Orchiectomy leads to the broadening of the adrenal cortex and testosterone replacement has an opposite effect. Ovariectomy has no effect on the structure of adrenal cortex and estradiol replacement resulted in the narrowing of zona glomerulosa. There were no differences in the nuclear-cytoplasmic ratio of zona glomerulosa cells in male and Female rats and neither gonadectomy nor gonadal hormone replacement has no effect on this parameter. The nuclear-cytoplasmic ratio of zona fasciculata cells in the male is markedly higher than in female. Orchiectomy lowers this ratio and testosterone restores it to the normal level. Neither ovariectomy nor estradiol replacement has effect on the nuclear-cytoplasmic ratio of zona fasciculata cells. Similar changes as those in the zona fasciculata were observed in zona reticularis cells. Among the oxidoreductases studied, the most marked sex differences were found in alpha-glycerophosphate dehydrogenase activity. In control female rats an intense reaction for this enzyme is observed in broad band of cells of the zona fasciculata interna, while in male rats only individual cells showed this reaction. In orchiectomized rats the reaction for this enzyme is similar as in control female rats and testosterone restores it to normal. Ovariectomy has no effect on localisation of reaction while after estradiol replacement reaction was more intense. Regarding the remaining oxidoreductases studied, in the adrenal cortex of rats of both sexes no marked differences were observed in localization, however, intensity of reaction depended upon applied experimental conditions. More distinct sex differences were observed in topochemistry of some hydrolases and intensity of reaction depended upon the applied experimental conditions.

Adrenal Cortex↗
PubMed1979

Transsphenoidal hypophysectomy in breast cancer: evidence for an individual role of pituitary and gonadal hormones in supporting tumor growth.

Transsphenoidal hypophysectomy was performed in 212 consecutive patients with metastatic breast cancer: 11 died within 30 days, two of surgical complications and nine of advanced metastatic disease. Two patients were unevaluable because of inadequate follow-up in one and simultaneous radiation treatment in the other. Of 199 evaluable patients 42% had an objective remission. Duration of remission averaged 18+ months with 10 out of 84 patients still in remission. Presence of estrogen receptors in the tumor significantly predicted response to hypophysectomy. Of 156 patients in whom completeness of hypophysectomy was assessed, 128 were thought to have a complete removal as shown by the fact that their growth hormone and prolactin were undetectable after stimulation with arginine or chlorpromazine, respectively. Of 26 patients in whom TRH test was performed, TSH and prolactin were undetectable in 20. Of 23 patients where autopsy was performed only six had microscopic pituitary tissue remaining. Hypophysectomy induced remission in eight of 15 patients who had previously responded and then relapsed to the antiestrogen Tamoxifen and in four of 17 who had failed. Conversely, antiestrogen therapy induced remission in six of 26 patients who had previously responded to hypophysectomy and in whom serum estrogens were present in small amount. These data indicate that both gonadal and pituitary hormones play a role in the growth of some human breast cancers.

Adult↗
PubMed1977

Influence of gonadal hormones and age on 1,2-dimethylhydrazine-induced colon carcinogenesis.

BD-II and BD-IX male and female rats received weekly subcutaneous (s.c.) injections of 15 mg/kg 1,2-dimethylhydrazine dihydrochloride (DMH) beginning at either 35, 120 or 210 days of age and continuing for 20 weeks. Control animals received only the DMH vehicle. Additional BD-II and BD-IX male and female rats of the three age groups were gonadectomized at 21, 106 and 196 days. Beginning 14 days after gonadectomy, the rats received 15 mg/kg of DMH by s.c. injection once a week for 20 weeks. Animals were sacrificed 35 weeks after the initial DMH injection. Control rats of the appropriate age and sex did not develop colon tumors. BD-IX rats are apparently more sensitive to DMH than BD-II rats. The incidence of DMH-induced cancer is less in females than in males in both the BD-II and BD-IX animals. Gonadectomy does not affect cancer incidence in either BD-II males or females nor in the BD-IX females but reduced the incidence in BD-IX males exposed initially at either 120 or 210 days. Administration of androgen to castrate BD-IX males (120-day-old group) increases the incidence of colon cancer to that approaching the intact animal but has little effect in the BD-II castrate male. These data suggest a genetically influenced susceptibility to DMH-induced colon carcinogenesis between BD-II and BD-IX rats. Furthermore, a sex difference is evident in both BD lines but age appears to be a factor only in older BD-IX females. Apparently, androgens influence DMH-induced tumorigenesis in BD-IX males only if the initial exposure of DMH occurs after sexual maturity.

Adenocarcinoma↗