摘要:

A single i.p. dose of 1 µC of 1,23H-testosterone (specific activity 147 µCi/µg) and 2 µC of 17β,6,7,-3H-estradiol (specific activity 178 µCi/µg) was injected into 2- to 10-day-old female rats and its distribution was studied after 5, 15, and 60 min in blood, cerebral cortex, hypothalamus, pituitary gland, liver, uterus, and spleen. The hypothalamus did not show preferential uptake of testosterone at the times studied. The amount of radioactivity per unit weight in the preoptic and ventral hypothalamus due to the testosterone injected was similar to the amount per unit weight found in the cerebral cortex at all times studied. Radioactivity levels recorded in the liver of the rats injected with testosterone suggest a metabolic activity toward this steroid, which is in marked contrast with the moderate uptake of the tritiated estradiol by hepatic tissue. Estrogenic and androgenic radioactivity distribution in the spleen was similar to that of the cerebral cortex control value. Active uptake of estrogen by the pituitary gland of these animals was not observed under the experimental conditions used. This fact cannot be explained by an incomplete maturation of the portal vessel system, because testosterone diffuses easily into the gland. However, when anterior pituitary lobes were incubated in vitro with the tritiated estrogen, a typical active uptake curve was observed, suggesting that the pituitary estradiol receptors are somehow masked by the physiological condition of the neonatal rat. In contrast to the pituitary, the uterus actively takes up labeled estrogen, in vivo, while testosterone is not accumulated but quickly diffuses out of the organ. Thin-layer chromatography studies showed that estrogen and testosterone are, apparently, somehow rapidly metabolized into more polar derivatives in the neonat

ISSN:0028-3835    

DOI:10.1159/000121941

出版商:S. Karger AG    

年代:1970

数据来源: Karger

摘要:

The amygdaloid complex of beagle dogs was acutely and chronically stimulated electrically, and peripheral plasma corticosteroids were measured by competitive protein-binding radioassay. Acute stimulation led to a rapid significant increase in concentration of peripheral plasma corticosteroids. This response was not maintained during prolonged stimulation. This is the first study in which peripheral blood corticosteroid levels were measured in the dog, following electrical stimulation.

ISSN:0028-3835    

DOI:10.1159/000121942

出版商:S. Karger AG    

年代:1970

数据来源: Karger

摘要:

Pituitary MSH content as measured by an in vitro bioassay was found to decrease 1 h after vaginal stimulation in rats at estrus. The values remained low up to the 6th day, but regained the pre-stimulation levels on the 10th day. The early decrease in pituitary MSH was not prevented if the animals were ovariectomized 2 h before the vaginal stimulation, but failed to occur in chronic ovariectomized rats MSH-release-inhibiting factor (MSH-R-IF) was found to increase in stalk median eminence (SME) extracts 2 h after vaginal stimulation in rats in the first day of diestrus, suggesting that the induction of pseudopregnancy (PSP) blocks the release of this agent. Animals ovariectomized 2 h after vaginal stimulation showed normal values of pituitary MSH two or six days later, indicating that the ovaries are necessary for maintaining the low content of the hormone during PSP. Administration of 2 mg progesterone daily to the spayed rats restored normal values. MSH-R-IF was absent in SME extracts from rats at day six of PSP or in ovariectomized animals treated with progesterone. It is concluded that there exist two stages in PSP induced by vaginal stimulation. During the first one (neurogenic phase), the stimulus promotes a low pituitary MSH content, probably by blocking the release of MSH-R-IF. During the second stage (hormone-neural phase), progesterone secreted by the ovaries assures continuance of the phenomenon, probably by blocking MSH-R-IF synthesis.

ISSN:0028-3835    

DOI:10.1159/000121943

出版商:S. Karger AG    

年代:1970

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000121944

出版商:S. Karger AG    

年代:1970

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000121945

出版商:S. Karger AG    

年代:1970

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000121931

出版商:S. Karger AG    

年代:1970

数据来源: Karger