摘要:

The effect of various putative neuro-transmitters upon the release of corticotrophin releasing hormone (CRH) was investigated using the hypothalamus of the rat in vitro. Acetylcholine (1–5 pg) caused a dose-dependent release of CRH which was antagonized by hexamethonium (1–10 ng) and partially antagonized by atropine (300 pg). Neither noradrenaline, dopamine nor histamine had any effect on the basal secretion of CRH. Noradrenaline (10 ng), however, was able to inhibit the release of CRH in response to acetylcholine (3 pg) and this action of noradrenaline was reduced by phentolamine (100 ng), an α adrenergic blocking a

ISSN:0028-3835    

DOI:10.1159/000122335

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

The intravenous administration of prostaglandin E2 (PGE2; 100 µg/rat) to immature male and female rats increased the serum level of luteinizing hormone (LH). This effect was prevented by the prior administration of an antiserum to the hypothalamic gonadotropin-releasing hormone. LH release from rat pituitaries in vitro was not stimulated by PGE2 (10 µg/ml). It is inferred that the stimulatory effect of PGE2, on LH release is not a direct one on the pituitary gland, but is exerted at the level of the hypothalamu

ISSN:0028-3835    

DOI:10.1159/000122336

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Resting and stress-induced plasma corticosterone concentrations in adult male hypophysectomized rats bearing a pituitary homograft in the hypothalamus were determined fluorimetrically. Plasma corticosterone resting levels were maintained and a significant elevation of these levels in response to stress occurred only in those rats in which the graft was in the medial basal hypothalamus (hypophysiotrophic area, HTA) and the implant was connected with the median eminence. If these latter connections of the graft in the HTA did not exist, resting plasma corticosterone concentrations were reduced and the applied stress did not induce any elevation of the low pre-stress levels. On the basis of the present and previous findings, it is assumed that the site of CRF production is the median eminence region.

ISSN:0028-3835    

DOI:10.1159/000122337

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

l7α-hydroxyprogesterone (up to 200 µg/day) and 11β-hydroxyandrostenedione (up to 500 µg) had n effect on PMS-induced ovulation in intact immature rats. 10 µg/day of testosterone propionate (TP) on days 28–30 of life decreased the percent of animals ovulating and the number of ova produced; this effect persisted in adrenalectomized animals with or without corticosterone replacement. Three daily doses of 10 µg TP increased the electrical threshold of the medial preoptic area in pentobarbital-blocked, PMS-stimulated animals. And TP decreased the rate of release and synthesis of FSH during the ovulatory surge, and the storage and rate of release of LH; it also inhibited the response to HCG in the PMS-primed animal, suggesting a direct target-organ

ISSN:0028-3835    

DOI:10.1159/000122338

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Fluorescence microscopy has shown that the guinea pig ovary contains not only vasomotor adrenergic nerves but also many nerve terminals running within endocrine structures. Electron microscopy of the interstitial gland confirmed the presence of adrenergic nerves distinguished by administration of the false transmitter, 5-hydroxydopamine. Axon varicosities, denuded of their Schwann cell ensheathing, innervated the endocrine cells in the interstitial gland, with a synaptic distance of approximately 400 Å. This suggests that the interstitial gland participates in a neuroendocrine transducer mechanism

ISSN:0028-3835    

DOI:10.1159/000122339

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

The pituitary response to LH-RH was studied at 8 a.m.,4 p.m. and 12 p.m. in normal male rats, female rats on day 1 of diestrus and female rats injected with testosterone propionate on the 2nd day of life. Androgenized rats responded to LH-RH with a greater release of LH than did female diestrous and male rats. In the 3 groups the lowest response to LH-RH was observed at 12 p.m., and the highest at 8 a.m., with the exception of androgenized rats which responded with a similar magnitude of LH release at 8 a.m. and 4 p.m. The release of FSH after the injection of LH-RH was studied only at 4 p.m. and only normal male rats responded with a significant FSH release.

ISSN:0028-3835    

DOI:10.1159/000122340

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Experiments have shown that the prolactin response specific to sustained teat stimulation is strictly dependent upon the duration of stimulation. There is some evidence for assuming two principally different patterns of prolactin response, namely high sensitivity to the stimulus with an initial maximal response, and poor sensitivity to the stimulus with a gradually intensifying response. Hyperstimulation of teats results in relative refractoriness of neural receptors for specific prolactin impulses. Refractoriness of one teat leads to a reduction in the release of prolactin which can be overcome by the stimulation of another as yet unstimulated teat.

ISSN:0028-3835    

DOI:10.1159/000122341

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

The extent of circadian variation in plasma corticosteroid levels at 30 days of age was normal in rats who received either intraventricular 6-OH dopamine or 5,6-dihydroxytryptamine on day 3 of life. A 4-h advance in the time of peaking was present in this latter group. At the time of study the depletion of 8.00 a.m. and 8.00 p.m. levels of norepinephrine was significant in the cortex (–49%), hypothalamus (–58%), hippocampus (–65%), and amygdala (–44%) of the 6-OH dopamine-treated animals, as was a similar depletion of serotonin in these areas in the 5,6-dihydroxytryptamine-treated animals. There was no difference between 8.00 a.m. and 8.00 p.m. levels of either amine in any of these areas, in contrast to the variation seen in uninjected animals in whom 8.00 a.m. levels of both amines were higher in all areas than 8.00 p.m. levels. The female 6-hydroxydopamine-treated animals had significantly increased adrenal weights. No other significant changes were noted in the adrenals or gonads of either treated group. Body weights were not significantly altered in any of the animals. These data demonstrate that the circadian variation in plasma corticosteroid levels can develop in the presence of either marked norepinephrine or serotonin depletion in CNS areas that have been implicated in the regulation of such peri

ISSN:0028-3835    

DOI:10.1159/000122342

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Adrenal venous blood samples were collectedfrom conscious and anesthetized dogs before and after an injection of pilocarpine and were analyzed for 17-hydroxycorticosteroids (17-OHCS). In conscious dogs the adrenal 17-OHCS secretion rate increased from a pre-injection secretion rate of 0.11 ± 0.014 to 1.58 ± 0.069 (mean ± SE) µg/kg/min following an intravenous injection of pilocarpine (0.3 mg/kg); there was a return to the baseline level by 120 min. In anesthetized dogs a marked increase in adrenal 17-OHCS secretion was also observed, which was completely abolished by hypophysectomy. A noticeable impairment of the adrenocortical response to pilocarpine was found to be produced by radio-frequency-current lesions of the anterior median eminence. A partial depression of the response was also observed in dogs with the anterior ventromedial hypothalamic lesions. Lesions destroying other hypothalamic areas were found to be without significant effect upon the adrenal cortical secretory response to pilocarp

ISSN:0028-3835    

DOI:10.1159/000122343

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Four- and 5-day cyclic mice housed with and without males, respectively, were autopsied at 10 a.m. on proestrus (P) or estrus (E) after no treatment, or after ovariectomy (Ovax) or sham Ovax at 10 a.m. or 4 p.m. on one of the preceding 3 days. Results indicate the ovaries must be in situ between 4 p.m. the day before P and 10 a.m. the day of P for a normal proestrous uterine weight increase to occur in both 4- and 5-day cyclic mice. For estrous cornification to occur, ovaries must be in situ between 10 a.m. and 4 p.m. on diestrus (D) in 4-day cyclic mice, and between 4 p.m. on D-I and 10 a.m. on D-II in 5-day cyclic mice. Sham Ovax tended to inhibit ovulation in both 4- and 5-day cyclic mice. The effects of both Ovax and sham Ovax on proestrous and estrous pituitary LH values were variable. Timing of the feedback relationship between ovary and hypothalamus-pituitary in mice may be imprecise, leading to easy disruption of the estrous cycle in this species.

ISSN:0028-3835    

DOI:10.1159/000122344

出版商:S. Karger AG    

年代:1975

数据来源: Karger