Induction of ovulation in immature hypophysectomized rats

Immature rats given minute doses of highly purified pituitary gonadotropins (follicle-stimulating hormone and luteinizing hormone) 7 to 100 days after hypophysectomy ovulated and formed corpora lutea. Neither hormone alone was effective. Luteinizing hormone repaired in part the atrophied theca interna and interstitial tissue, and follicle-stimulating hormone stimulated the development of the granulosa cells.     

Gamma-aminobutyric acid effects on pituitary gonadotropin secretion

Gamma-aminobutyric acid (GABA) injected into the third ventricle of male rats promotes the release of pituitary luteinizing hormone (LH) but not follicle-stimulating hormone. When GABA was injected directly into the pituitary it was ineffective in promoting LH release. This evidence suggests that GABA may play a role in controlling the discharge of hypothalamic luteinizing hormone releasing factor.     

Luteinizing hormone: action on the graafian follicle in vitro

Graafian follicles, dissected intact from the rabbit ovary and incubated for 40 minutes with luteinizing hormone, developed into corpora lutea when autotransplanted under the kidney capsule. Follicles incubated with follicle-stimulating hormone or without hormone degenerated and failed to luteinize. Direct exposure of the mammalian follicle to luteinizing hormone initiates luteinization and formation of the corpus luteum.     

Growth factors modulate gonadotropin receptor induction in granulosa cell cultures

Epidermal growth factor and fibroblast growth factor inhibited follicle-stimulating hormone-dependent induction of luteinizing hormone receptor in cultured ovarian granulosa cells of the rat. In contrast, platelet-derived growth factor potentiated the induction of luteinizing hormone receptor by follicle-stimulating hormone. These results indicate that growth factors, well known for their effects on mitosis and DNA synthesis in cultured mammalian cells, are also able to modulate hormone-dependent differentiation in an endocrine target cell.     

THE ISOLATION IN PURE FORM OF THE INTERSTITIAL CELL-STIMULATING (LUTEINIZING) HORMONE OF THE ANTERIOR LOBE OF THE PITUITARY GLAND

Interstitial cell-stimulating (luteinizing) hormone was isolated from swine pituitary glands. This protein hormone, having a molecular weight of about 90,000 and an isoelectric point of pH 7.45, was shown to be pure by tests in the electrophoresis apparatus of Tiselius and in the ultracentrifuge as well as by its constant solubility. The hormone stimulated the interstitial tissue of the testis or ovary and caused the formation of corpora lutea provided that maturing follicles were present. Under the conditions described, its minimal effective total dose in hypophysectomized immature male rats was about 1 microgram of nitrogen or 6.7 micrograms of hormone. Extracts of swine pituitary with purely follicle-stimulating effects did not cause oestrus in immature hypophysectomized female rats unless luteinizing hormone was also administered.     

The hypogonadal mouse: reproductive functions restored by gene therapy

The hypogonadal (hpg) mouse lacks a complete gonadotropin-releasing hormone (GnRH) gene and consequently cannot reproduce. Introduction of an intact GnRH gene into the genome of these mutant mice resulted in complete reversal of the hypogonadal phenotype. Transgenic hpg/hpg homozygotes of both sexes were capable of mating and producing offspring. Pituitary and serum concentrations of luteinizing hormone, follicle-stimulating hormone, and prolactin were restored to those of normal animals. Immunocytochemistry and in situ hybridization showed that GnRH expression was restored in the appropriate hypothalamic neurons of the transgenic hpg animals, an indication of neural-specific expression of the introduced gene.     

Paradoxical elevation of growth hormone by intraventricular somatostatin: possible ultrashort-loop feedback

Somatostatin, the growth hormone-inhibiting factor, when microinjected into the third ventricle of the rat brain, paradoxically induced the release of growth hormone. A pituitary site of action having been ruled out, this result supports the concept that exogenous somatostatin within the hypothalamus acts either to suppress the release of somatostatin from somatostatin-containing neurons, possibly via an ultrashort-loop feedback mechanism, or to augment release of hypothalamic growth hormone-releasing factor, thereby inducing a release of growth hormone. Injection of somatostatin into the third ventricle also decreased plasma concentrations of luteinizing hormone, follicle-stimulating hormone, and thyroid-stimulating hormone, probably by inhibiting the release of luteinizing hormone-releasing factor and thyrotropin-releasing factor.     

光照控制对蒙古羊发情排卵及相关生殖激素分泌的影响

通过模拟绵羊繁殖季节前后的光照条件,研究光照控制对蒙古绵羊血液褪黑激素(MLT)、促卵泡素(FSH)、促黄体素(LH)浓度分泌的影响,探讨光照条件在控制绵羊繁殖季节中的作用.结果表明:光照控制可诱导蒙古羊在非繁殖季节发情并排卵,对蒙古羊血液MLT分泌影响显著,而对血液FSH和LH分泌没有显著影响.     

Induction of mating behavior in rats by luteinizing hormone-releasing factor

Ovariectomized female rats treated with estrogen, in dosages too low to provoke mating, displayed this behavior when given subcutaneous injections of synthetic luteinizing hormone-releasing factor (LRF) 48 hours later. Two hours after the injection of LRF, components of female sexual behavior appeared. The lordosis reflex followed mounting by the male, and darting and hopping behavior was quite prevalent. On the other hand, treatment with estrogen followed by luteinizing hormone, follicle-stimulating hormone, or thyrotropin-releasing factor did not induce copulatory behavior. The results suggest that LRF may play a role in induction of mating behavior.     

Follicle-stimulating hormone secretion in the female rat: cyclic release is dependent on circulating androgen

In adult cyclic female rats, intravenous injections of an antiserum to testosterone prevented the continued increase in serum follicle-stimulating hormone (FSH) which normally occurs during the early morning hours of estrus. This treatment did not prevent the initial increases in serum FSH (and luteinizing hormone) which occur during the critical period (1400 to 2000 of proestrus), nor did it interfere with subsequent ovulation. These observations indicate the existence of two separate mechanisms for preovulatory FSH release in the rat and implicate circulating testosterone as the stimulus for continued secretion of FSH during estrus.     

吉林地方特色肉牛发情周期内生殖激素变化规律研究

[目的]研究吉林地方特色肉牛发情周期体内生殖激素的变化规律,为提高国产特色肉牛繁殖效率提供理论依据。[方法]以吉林地区优质的草原红牛和延边黄牛,以及西门塔尔为试验对象,对发情周期内3个品种牛的血清与尿样中的孕酮、雌二醇,促卵泡素、促黄体素的变化进行测定和对比。[结果]发情第21天已孕与未孕肉牛的孕酮和雌二醇含量均存在极显著差异（P〈0.01）,促黄体素含量在发情当天与其他天相比有显著差异（P〈0.05）。[结论]通过检测肉牛发情早期血液中孕酮含量对发情鉴定及早期妊娠的诊断是切实可行的。     

Synthetic polypeptide antagonists of the hypothalamic luteinizing hormone releasing factor

Two analogs of the hypothalamic luteinizing hormone releasing factor modified at the histidine-2 position were tested for biological activity (secretion of luteinizing hormone) in cultures of dispersed rat anterior pituitary cells. The analog in which glycine was substituted for histidine at position 2, [Gly(2)]LRF, behaves as a partial agonist releasing less than 50 percent of the luteinizing hormone secreted at maximum concentrations of the releasing factor, while the analog in which histidine at position 2 is deleted has no significant agonist activity at any of the doses tested. When added to the cultured cells at molar ratios 10(3) to 10(4) times that of the luteinizing hormone releasing factor, both analogs decrease the amount of luteinizing hormone secreted in response to the releasing factor.     

Inhibin-mediated feedback control of follicle-stimulating hormone secretion in the female rat

The secretion of follicle-stimulating hormone (FSH) by the anterior pituitary gland is regulated by the interaction of hypothalamic and gonadal hormones. Recently, proteins termed inhibins that selectively suppress FSH secretion have been purified and characterized from the gonadal fluids of several species. Antibodies to a synthetic peptide encompassing the amino terminal 25 residues of the recently characterized porcine inhibin were used to develop a specific radioimmunoassay (RIA) for inhibin and to neutralize endogenous inhibin during the estrous cycle of the rat. The administration of 20 international units of pregnant mare serum gonadotropin (PMSG) stimulated the secretion of inhibin in intact immature female rats, whereas ovariectomy caused an abrupt decrease in plasma inhibin concentrations that were not prevented by the injection of PMSG. The infusion of a polyclonal antiserum to inhibin, from 12 noon on proestrus to 1 a.m. on the morning of estrus, as well as its acute intravenous injection during diestrus I or II, caused an increase in plasma FSH (but not luteinizing hormone) concentrations. These results support the hypothesis of a feedback loop between the release of ovarian inhibin and FSH in the female rat.     

疏肝健脾解毒方对乳腺癌癌前病变肝郁证模型大鼠血清性激素水平的影响

目的 研究疏肝健脾解毒方对乳腺癌癌前病变肝郁证模型大鼠血清性激素水平的影响。方法 采用二甲基苯蒽灌胃及夹尾法制备乳腺癌癌前病变肝郁证大鼠模型,随机分为模型组、疏肝健脾解毒方组、三苯氧胺组、小金丸组,同时设空白对照组,分别干预4周后采用放射免疫法检测血清雌二醇、孕酮、泌乳素、黄体生成素和卵泡刺激素含量。结果 模型组血清雌二醇、孕酮、泌乳素、黄体生成素和卵泡刺激素水平均较空白对照组高,差异均有显著统计学意义（P<0.01）;各用药组血清性激素水平低于模型组,差异均有显著统计学意义（P<0.01）;疏肝健脾解毒方组雌二醇及黄体生成素水平低于对照药三苯氧胺组及小金丸组,差异均有统计学意义（P<0.05）;疏肝健脾解毒方组血清孕酮、卵泡刺激素、泌乳素水平高于三苯氧胺组,低于小金丸组,孕酮水平间差异有统计学意义（P<0.01）,卵泡刺激素、泌乳素水平水平间差异无统计学意义（P>0.05）。结论 疏肝健脾解毒方可有效降低乳腺癌癌前病变肝郁证大鼠模型血清性激素水平。     

Progesterone administration in vivo stimulates release of luteinizing hormone-releasing hormone in vitro

The release of luteinizing hormone-releasing hormone (LHRH) from tissue from the mediobasal hypothalamic-anterior hypothalamic-preoptic area of prepuberal female rats was measured in a perfusion system. Measurements were also made of the concentrations of LHRH in these tissue fragments and of luteinizing hormone in serum obtained when the rats were killed. Four groups of immature rats were studied: intact, ovariectomized, ovariectomized and implanted with estradiol-containing capsules, and ovariectomized rats primed with estradiol and injected with progesterone. The release of LHRH from the tissue of ovariectomized animals was significantly less than that of intact females and was not modified when the ovariectomized rats received estradiol. However, there was a four- to fivefold increase in LHRH release from tissue of ovariectomized rats primed with estradiol when they were killed 6 hours after they received an injection of progesterone. The concentrations of LHRH in tissue and of luteinizing hormone in serum varied among groups and with the time of day that the animals were killed. The interactions among luteinizing hormone, gonadal steroids, and the photoperiod seem to set the appropriate conditions for neural processes triggering a complete and normal release of luteinizing hormone.     

Gonadotropin secretion during sleep in normal adult men

Release of luteinizing hormone and follicle stimulating hormone during sleep in young adult men occurred in unrelated, random, arrhythmic peaks, with no consistency from night to night in the same subject. Release of luteinizing hormone was modestly but significantly larger (14 perecnt) during rapid-eye-movement sleep than it was in non-REM sleep, but release of follicle stimulating hormone was not clearly related to stages of sleep.     

Dynamic changes in inhibin messenger RNAs in rat ovarian follicles during the reproductive cycle

The alterations in morphology and function of the ovarian follicle as it matures, ovulates, and becomes a corpus luteum are dramatic. A variety of steroid and polypeptide hormones influence these processes, and the ovary in turn produces specific hormonal signals for endocrine regulation. One such signal is inhibin, a heterodimeric protein that suppresses the secretion of follicle-stimulating hormone from pituitary gonadotrophs. Rat inhibin complementary DNA probes have been used to examine the levels and distribution of inhibin alpha-and beta A-subunit messenger RNAs in the ovaries of cycling animals. Striking, dynamic changes have been found in inhibin messenger RNA accumulation during the developmental maturation of the ovarian follicle.     

Luteinizing hormone-releasing activity in hypophysial stalk blood and elevation by dopamine

Pituitary halves incubated in pituitary stalk plasma release more luteinizing hormone than their opposite halves incubated in plasma from peripheral blood. Glands incubated in stalk plasma from dopamine-treated rats release more luteinizing hormone than glands incubated in stalk plasma from untreated controls. Luteinizing hormone-releasing activity in stalk plasma may be due to the luteinizing hormone-releasing factor, and the secretion of luteinizing hormone-releasing factor may be controlled by a dopaminergic mechanism.     

慢性暴露全氟十二烷酸对雌性大鼠生殖激素及相关卵巢受体表达的影响

全氟烷酸类化合物(PFAAs)是一类新型的持久性有机污染物,该类化合物的环境和健康风险已经引起了人们的广泛关注。由于长链PFAAs的生殖毒性效应尚缺乏系统的研究,本文采用含全氟十二烷酸(PFDoA)0.1 mg/kg的饲料饲喂大鼠180 d,应用放射免疫分析法和实时荧光定量PCR方法检测了大鼠血清中生殖激素的水平以及卵巢中相关受体的表达。结果显示,PFDoA暴露导致血清雌二醇水平出现减少的趋势,PFDoA显著增加了血清促卵泡刺激素水平,但并不影响血清促黄体生成素水平;PFDoA处理导致卵巢雌激素受体α的mRNA水平降低了25%,卵巢促卵泡刺激素受体的表达增加了36%,但PFDoA并不影响卵巢中促黄体生成素受体的表达。以上结果暗示慢性PFDoA暴露有影响雌激素以及促卵泡刺激素的信号在卵巢中传导的趋势。