Adrenoceptors in the preoptic-anterior hypothalamic area stimulate secretion of prolactin but not growth hormone in the male rat

Plasma growth hormone (GH) and prolactin concentrations were measured by radioimmunoassay in unanesthetized male rats after stereotaxic microinjection of adrenergic agents and 6-hydroxydopamine into the preoptic-anterior hypothalamic area (PO/AHA). Norepinephrine, epinephrine, isoprenaline and clonidine failed to stimulate GH, moreover, 16 nanomoles norepinephrine produced a decrease. However, these agents stimulated prolactin secretion and the mixed alpha antagonist phentolamine, administered systemically, inhibited the stimulatory action of epinephrine on prolactin secretion. GH and prolactin secretory patterns were not affected by 6-hydroxydopamine disruption of catecholamine terminals in the PO/AHA. GH responses to adrenergic agonists and the failure of 6-hydroxydopamine to affect GH secretory patterns indicate that PO/AHA norepinephrine afferents do not facilitate GH secretion. Taken in conjunction with previous studies, the results suggest that there must be an extra-hypothalamic site at which norepinephrine is stimulatory for GH. Prolactin responses suggest that alpha adrenoceptors in the PO/AHA may participate in prolactin secretion.     

The effect of acute and repeated electroconvulsive treatment on plasma β-endorphin,growth hormone,prolactin and cortisol secretion in depressed patients

The effects of single and repeated electroconvulsive treatment (ECT) on β-endorphin (β-EP), cortisol, growth hormone (GH) and prolactin (Prl) plasma levels were investigated in nine depressed patients. Blood samples were monitored a day before ECT, the day of the first and sixth ECT (0, 30, 60 and 90 min after seizures), the day afterwards and 4 weeks after termination of the ECT course. A significant elevation of β-EP levels was achieved immediately with and 24 h after the first and the sixth ECT. A transient increase in basal β-EP was observed 1 day following the sixth ECT in comparison with pre-treatment level. Peak and 30 min levels of cortisol were increased compared with baseline by the first ECT. The former (peak) but not the latter (30 min) were increased also at the sixth treatment. GH levels were decreased the day after the first ECT in comparison with the pre-treatment levels and immediately following each ECT in comparison with baseline. A trend toward elevation of Prl was observed immediately after the first and sixth ECT, although the rise did not reach significant levels. ECT administration stimulated β-EP and cortisol secretion and suppressed human GH release, possibly by activation of endorphinergic and/or serotonergic systems. These mechanisms might be involved in the beneficial effect of ECT in depression.     

剖宫产术后不同镇痛方式对产妇泌乳量的影响

目的 :观察应用不同方式行剖宫产术后镇痛 ,对疼痛及泌乳的影响 ,以探讨剖宫产术后最佳镇痛方法。方法 :选择孕足月剖宫产 16 0例随机均分为四组 :一组术前麻醉同时行蛛网膜下腔小剂量吗啡镇痛 ;二组术前行蛛网膜下腔小剂量吗啡镇痛 ,术后硬膜外 2 4h后追加一次吗啡镇痛 ;三组术前麻醉同时行蛛网膜下腔小剂量吗啡镇痛 ,术毕行硬膜外吗啡加氟哌利多镇痛 ;四组未行术后镇痛。另选 40例足月正常分娩产妇作为对照。应用放射免疫法测定产后血清泌乳素。结果 :产后 5 min、 2 4h、 48h PRL 值各组间差异无显著性。剖宫产术后疼痛平均出现时间第一、三组间差异无显著 (P>0 .0 5 ) ;第四组出现时间最早与第一、三组间比较差异显著 (P<0 .0 1) ,第二组出现时间平均大于 48h,与第一、三组间及第四组间比较差异显著 (P<0 .0 5或 0 ,0 1)。术后肛门排气、乳胀出现时间各组间比较差异无显著性 (P>0 .0 5 )。初次哺乳时间、日哺乳次数及新生儿体重下降情况第四组与其他组间比较差异显著 (P<0 .0 5 ) ,其他组间比较差异无显著性 (P>0 .0 5 )。第四组有 11例乳汁分泌不足或严重不足 ,与其他组间比较差异显著 (P<0 .0 5或 0 .0 1) ,其他各组间比较差异无显著性 (P>0 .0 5 )。结论 :剖宫产术后镇痛不影响产后泌乳 ;术前蛛?     

Zolmitriptan-induced growth hormone release in humans: mediation by 5-HT1D receptors?

Rationale: Effective neuroendocrine probes of 5-HT_1B and 5-HT_1D receptor function may facilitate investigation of the role of these receptor subtypes in the pathophysiology of depression and the mode of action of antidepressant medication. Objective: To investigate the neuroendocrine profile of the 5-HT_1B/1D receptor agonist, zolmitriptan, in healthy volunteers. Methods: Twelve subjects entered a double-blind, placebo-controlled, cross-over design study of zolmitriptan (5 mg orally). Blood samples were taken at 15-min intervals for assay of prolactin and growth hormone. A further six healthy men were recruited to an equivalent study to examine the effect of ketanserin (a 5-HT receptor antagonist with some preference for 5-HT_1D over 5-HT_1B receptors) on the growth hormone response to zolmitriptan. Results: Zolmitriptan significantly increased plasma growth hormone but had no effect on plasma prolactin or oral temperature. The increase in growth hormone produced by zolmitriptan was significantly attenuated by ketanserin. Conclusions: We suggest that the ability of triptans such as zolmitriptan, sumatriptan and rizatriptan to increase plasma growth hormone is mediated by their common agonist activity at postsynaptic 5-HT_1D receptors. Received: 16 December 1998 / Final version: 11 March 1999     

Alterations in hypothalamic serotonin metabolism in male hamsters with photoperiod-induced testicular regression

Transfer of adult male golden hamsters to a short photoperiod (SD; 8L:16D) resulted in a significant decrease in testicular weight and plasma luteinizing hormone (LH) and prolactin (Prl) levels as compared to animals maintained in a long photoperiod (LD; 16L:8D). These changes were accompanied by significant increases in serotonin (5-HT) synthesis in the medial basal hypothalamus (MBH) as determined by measuring 5-hydroxytryptophan accumulation after inhibition of aromatic amino acid decarboxylase with NSD-1015. Serotonin synthesis in the median eminence, anterior hypothalamus and olfactory bulbs was not different in SD vs LD animals. Transfer of SD gonadally regressed hamsters to LD restored MBH 5-HT synthesis to control levels.     

复方甲地孕酮微囊注射液对大鼠垂体前叶超微结构的影响

用不同剂量的复方甲地孕酮微囊注射液注射大鼠,观察垂体前叶催乳激素细胞和促性腺激素细胞的超微结构变化,结果在一定剂量下,对催乳激素细胞有促进作用,促性腺激素细胞在0.2ml和0.4ml组出现抑制性改变。各实验组催乳激素细胞的内质网呈现同心圆排列,同心圆数目与对照组相比,差异有高度显著性(P<0.005)。随着剂量增加,出现髓样变结构的细胞增多,其0.4ml组与对照组相比,差异有高度显著性(P<0.005)。     

Vasoactive intestinal peptide affects the GABAergic system in the hypothalamic-pituitary axis

The effect of a specific antiserum against vasoactive intestinal peptide (VIP) on GABA in the hypothalamic-pituitary axis was studied. The administration of anti-VIP serum (A-VIP) increased anterior pituitary GABA concentration in control rats, but decreased this neurotransmitter in rats with hyperprolactinemia induced by acute or chronic treatments with estrogens, or by the implanting of anterior pituitary glands under the kidney capsule. Besides, the injection of the A-VIP serum in the morning in proestrous rats causes a decrease in anterior pituitary GABA concentration, measured in the afternoon of the same day. The in vitro effect of A-VIP and VIP on endogenous GABA release from hypothalamic fragments and on anterior pituitary GABA concentration was studied. A-VIP increased both basal and high K(+)-evoked GABA effluxes whereas VIP produced a decrease in evoked GABA efflux from hypothalamic fragments. Furthermore, A-VIP inhibited the normal degradation of GABA that occurs in the isolated gland whereas VIP increased it. These results suggest that VIP modifies hypothalamic GABA release and anterior pituitary GABA concentration.     

Hyperprolactinemia stimulates food intake in the female rat

Lactation in the rat is marked by extreme hyperphagia. The present study examined the possibility that elevated prolactin levels contribute to this increase. It also evaluated the effects of hyperprolactinemia on brown adipose tissue and carcass composition. Virgin Osborne-Mendel rats were made hyperprolactinemic via ectopic pituitary transplants (PIT, n = 9) or were sham-operated (SHAM, n = 8). Eight lactating rats (LACT) served as additional controls. Food intake, body weight and rectal temperature were recorded daily. Eleven days postsurgery (or 11-12 days postpartum), the rats were sacrificed, and brown fat (scapular, axillary, cervical and thoracic) was excised, weighed, and assayed for GDP binding, one indicator of thermogenic capacity. Carcasses were subjected to body composition analysis. Although prior to surgery, PIT and SHAM rats weighed the same, PIT rats gained significantly more weight during the experiment than did SHAMs. Percent body fat and food intake (both total intake and intake relative to metabolic body size) were significantly elevated in the PIT rats. GDP binding in both PIT and LACT rats was significantly less than in SHAMs. This was true whether GDP binding was expressed per mg mitochondrial protein or per total amount of mitochondrial protein recovered. These data confirm that brown fat thermogenic capacity is suppressed during lactation. They also demonstrate that elevations of serum prolactin, to levels that are well within physiological limits, are capable of stimulating food intake and white fat deposition in the female rat. It is presently unclear whether these results are a direct or an indirect effect of hyperprolactinemia.     

中老年男性血清催乳素水平与良性前列腺增生的关系

目的　探讨中老年男性血清催乳素 (PRL)和睾酮 (T)的变化 ,研究PRL与良性前列腺增生的关系。　方法　将 84例健康中老年男性分为 4个年龄组 ,测定血清PRL和T水平 ,分析不同年龄组的数值变化。采用B超测定其中 38例的前列腺体积 ,与PRL进行相关性分析。　结果　 5 0、6 0、70和 80岁年龄组的T水平分别为 (2 5 .92± 2 .5 4)、(2 1.0 0± 1.92 )、(18.37± 2 .49)和 (14.75±2 .38)nmol/L ,不同年龄组之间T水平比较 ,差别有显著性意义 (F =3.44 ,P <0 .0 5 ) ;PRL水平分别为 (1.11± 0 .16 )、(0 .96± 0 .2 0 )、(0 .99± 0 .18)和 (0 .91± 0 .2 9)nmol/L ,组间比较差别无显著性意义(F =0 .12 ,P >0 .0 5 ) ;PRL水平与前列腺体积无显著相关性 (r =0 .2 5 ,P >0 .0 5 )。　结论　PRL通过雄激素在前列腺的生长过程中产生作用 ,但中老年男性雄激素水平不断降低 ,削弱了PRL在前列腺增生中的作用。