ISSN:0028-3835    

DOI:10.1159/000122726

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The effects of sex steroids on luteinizing hormone (LH) secretion in rabbits of both sexes castrated for at least 2 weeks previously were investigated. An intramuscular (i.m.) injection of testosterone propionate (TP) or estradiol benzoate (EB) was given about midway through blood sampling which ranged from 6 to 12 h. LH and steroids were measured by established radioimmunoassay (RIA) procedures. Variable responses were obtained with animals. Castration itself in most instances led to increases in circulating levels of LH which ranged from normal levels to greater than 200 ng/ml with some evidence for episodic variation. EB was more effective than TP in reducing LH levels and inhibiting episodic release.

ISSN:0028-3835    

DOI:10.1159/000122727

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

[3H]-dopamine (DA) binding to bovine anterior pituitary membranes was measured using sensitive in vitro ultrafiltration and centrifugation techniques. The specific interaction of [3H]-DA with the membrane fraction reached a steady-state level within 15 min at 30°C and was reversible by incubating with excess nonradioactive DA. Scatchard analysis suggests the presence of 2 sites for DA specific binding having K < j values of 4.4 × 10–10 M and 4.7 × 10–8 M, respectively. Correspondingly, the total receptor concentrations were calculated to be 336 and 2,340 pmoles/g protein. Blockade of [3H]-DA binding was produced most effectively by ergocryptine and apomorphine. Perphenazine and haloperidol were considerably less active and pimozide did not compete. The importance of DA in the regulation of prolactin (Prl) secretion and the characterization of pituitary DA receptor sites are dis

ISSN:0028-3835    

DOI:10.1159/000122762

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Using incubated glands, we showed that cerebral cortex and liver extracts (CCE and LE) stimulated ACTH release from neurointermediate lobe (NIL) of hypophysis as well as hypothalamus extract (HE) did. Moreover, the HE-induced ACTH release was much smaller for the NIL (1.9 × basal level) than for the anterior lobe (AL; 13.7 × basal level). Thus, under these conditions, HE seemed to have no specific effect on NIL ACTH release. Using superfused glands, we showed: (a) that both spontaneous and HE-induced ACTH release decreased during superfusion; (b) that using this system, a specific stimulatory effect of HE on NIL was observed. In contrast to HE, CCE and LE had only a small effect on NIL ACTH release (always less than 20% of that caused by HE) which could be considered as a nonspecific response; (c) that trypsin suppressed the stimulating effect of HE as well on NIL as on AL; and (d) that arginine antidiuretic hormone (ADH) was not responsible for the stimulating effect of HE on NIL ACTH release, because synthetic ADH had no effect and HE containing ADH (from normal rats) or HE containing no ADH (from Brattleboro rats or from immunoneutralization of ADH in normal HE) had the same effect. From these results, we can conclude that HE contain a peptidic factor different from ADH which is able to stimulate in vitro release of ACTH from the NI

ISSN:0028-3835    

DOI:10.1159/000122728

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000122729

出版商:S. Karger AG    

年代:1978

数据来源: Karger