摘要:

Naloxone (NAL) has been shown to induce LH release in female but not in male rats 10–25 days of age. The purpose of this study was to examine the role of neonatal gonadal hormones on NAL-induced LH release in male and female rats 15, 25, and 35 days of age. On each of these days rats received a s.c. injection of either NAL (5 mg/kg) or physiological saline, and blood was collected 30 min later by decapitation. At 15 days of age, NAL induced LH release in intact and ovariectomized (OVX) female rats, and in male rats castrated (CAST) on the 1st day of life (neonate CAST males). Injection of 10 µg estradiol benzoate (EB) 24 h prior to NAL administration blocked NAL-induced LH release in these rats. NAL had no effect on LH release in 15- or 25-day-old intact and CAST male rats or in female rats given 2 mg testosterone propionate at 3 days of age (androgenized female rats). At 35 days of age, NAL induced LH release in intact, OVX, and OVX-EB treated female rats, and in neonate CAST and neonate CAST-EB treated male rats. NAL had no effect on serum LH levels in androgenized female rats. NAL induced LH release in intact and CAST 35-day-old male rats, but pretreatment with estrogen prevented NAL from eliciting LH release. These results indicate that neonatal exposure to androgen is responsible for the sex difference in the LH response to NAL observed in prepubertal male and female rats before 30 days of age. They also show that the ability of NAL to induce LH release develops earlier in female and neonate CAST males than in intact male or androgenized female ra

ISSN:0028-3835    

DOI:10.1159/000124069

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

The ‘secretory vesicle hypothesis of precursor processing’ states that the initial endopeptidase cleavages which excise the nascent, biologically active peptides from their protein precursors occur primarily in secretory vesicles (or granules). Hence, all the processing steps subsequent to these cleavages must also occur within these organelles. Two types of evidence are presented in support of this view: (1) cell biological studies which implicate the secretory vesicle as the site of precursor conversion to peptides, and (2) enzymological studies which locate and characterize putative processing enzymes in secretory vesicles. The processing enzymes reviewed include the ‘prohormone-converting enzymes’ which cleave at pairs of basic amino acids, other endopeptidases, carboxypeptidase-B-like enzymes and aminopeptidase, and N-acetylation and α-amidation enzymes. The properties of these enzymes in relation to the nature of the processing micro-environment in the secretory vesicles is d

ISSN:0028-3835    

DOI:10.1159/000124070

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

We investigated the effect of blocking endogenous LH-RH, by injection of anti-LH-RH sera, on serum prolactin levels previously elevated by treatment with haloperidol for 5 days. An acute intravenous injection of rabbit anti-LH-RH serum significantly reduced serum LH levels and blocked the hyperprolactinemia induced by haloperidol. In another group of rats, sheep anti-LH-RH serum induced a significant decrease of serum LH and also lowered serum prolactin levels previously elevated by haloperidol. In ovariectomized rats, sheep anti-LH-RH serum markedly reduced serum LH levels and also decreased serum prolactin elevated by the pretreatment with haloperidol. It is concluded that the blocking of endogenous LH-RH action results in a decreased release of prolactin in response to stimuli like haloperidol. These results support the possible existence of a paracrine interaction between the pituitary gonadotrophs and lactotrophs.

ISSN:0028-3835    

DOI:10.1159/000124071

出版商:S. Karger AG    

年代:1985

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000124072

出版商:S. Karger AG    

年代:1985

数据来源: Karger