摘要:

Using heterologous radioimmunoassay systems, it has been possible to demonstrate a complete cross-reaction between partially purified preparations of guinea pig FSH and LH and the corresponding rat gonadotrophìns. On this basis, radioimmuno-assays for these 2 gonadotrophìns have been established and they have been used in order to study changes in blood hormonal levels during the estrous cycle. There is a serum LH peak during estrus shortly before ovulation. At ovulation, serum LH levels show a smaller increase which is maintained for 1 or 2 days. The changes in serum FSH levels do not systematically coincide with those of LH. A parallel study of the changes in serum progesterone and estradiol was also performed. The levels of estrogen increased during the pre-ovulatory period, reaching a maximum shortly before the pre-ovulatory LH peak. Progesterone does not increase until shortly thereafte

ISSN:0028-3835    

DOI:10.1159/000122420

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

The hypophysial portal vessels and anterior pituitary glands of adult male rats were surgically exposed, cannulated and infused for 1 min with saline, growth hormone-releasing factor (GH-RF), and dbcAMP. After cessation of infusion, anterior pituitary glands were collected at 1,5, 15, 30 or 60 min for electron microscopic and ultra-structural cytochemical examination. Before and after cannulation of a portal vessel a 1-ml sample of blood was collected at 1, 5, 15, 30 or 60 min from the femoral vein for RIA of growth hormone. When viewed ultrastructurally, the initial response following the infusion of GH-RF into a portal vessel was one of granule release. Emiocytic activity was observed at all time intervals studied. This response was followed 30 min later by evidence of increased protein synthesis. Significant increases in plasma GH levels were present at 1, 5, and 15 min following infusion of GH-RF but not at 30 or 60 min. Preliminary analysis of the RIA data suggests that dbcAMP was significantly more potent than GH-RF in elevating radioimmunoassayable plasma GH levels. The results suggest that similar mechanisms of synthesis and release were involved.

ISSN:0028-3835    

DOI:10.1159/000122421

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

The neural substrate for estrogen (E) and E plus progesterone (P)-induced sexual receptivity was examined in 3 classes of adult rats: adult females ovariectomized for 11 days, and females and males gonadectomized on the day of birth. E responses were found only after implantation in the preoptic or medial hypothalamus; adult females had the largest fraction of responders. The addition of P significantly increased the fraction of adult and neonatally ovariectomized females responding when E implantation was made throughout the hypothalamus from preoptic to mammillary bodies. No E-P synergistic effects were seen in the day-1 gonadectomized males. E-P synergistic effects were found in the amygdala of the adult ovariectomized females. However, midbrain implants of E were ineffective for facilitating E-P-induced receptivity in the 3 classes of animals studied.

ISSN:0028-3835    

DOI:10.1159/000122422

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Pituitary 5α-reductase activity in intact male rats increases after the pituitary is incubated with the hypothalamus. Incubating the pituitary of castrate rats with the hypothalamus of intact rats relatively inhibits pituitary 5α-reductase activity. Coincubation of the pituitary and hypothalamus of castrate rats, or the pituitary of intact with the hypothalamus of castrate males, does not elicit changes in pituitary 5α-reductase activity. Different amounts of LH-RH in the incubation medium can modify 5α-reductase activity, i.e., activate it in the intact pituitary and inhibit it in the castrate pituitary. Hypothalamus from intact rats, which according to Shin et al. [1974] is ‘rich’ in LH-RH, induces changes in pituitary 5α-reductase activity. The LH-RH-’poor’ hypothalamus of castrate rats does not cause changes in this enzyme activity. The results suggest that there is a very close relationship between LH-RH and 5α-reductase activity in

ISSN:0028-3835    

DOI:10.1159/000122423

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Bilateral superior cervical ganglionectomy or exposure of rats to light for 10 days resulted in comparable increases in microtubule protein content in the hypothalamus. Administration of norepinephrine, L-dopa or isoproterenol decreased hypothalamic tubulin levels to a greater extent in ganglionectomized rats. A prior injection of phentolamine prevented norepinephrine’s effects in intact rats and decreased but did not abolish the effect of the catecholamine in ganglionectomized animals. Phentolamine impaired L-dopa activity in intact and denervated rats as did propranolol; beta-adrenergic blockage impaired the effect of norepinephrine in denervated rats and abolished that of isoproterenol. Phentolamine plus propranolol prevented norepinephrine’s effects whereas it only impaired L-dopa activity on hypothalamic tubulin content. The prior administration of actinomycin D blocked the effects of norepinephrine, L-dopa or isoproterenol. Pinealectomy abolished the isoproterenol-induced decrease in microtubule protein content and impaired that following L-dopa. These data suggest that tubulin levels of the rat hypothalamus are controlled by adrenergic transmitter via alpha- and beta-receptors, the latter involving the pineal gl

ISSN:0028-3835    

DOI:10.1159/000122424

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Lactating female rats reared litters consisting of 4, 8 or 12 pups. At weaning (21 days) females were removed from their maternity cages and exposed to a 1-min ether stress followed by heart puncture. The animals were then isolated and 14 min after the termination of ether stress blood was collected by decapitation. Plasma prolactin and corticosterone were assayed in the blood collected from heart puncture, and in the 14-min stress blood. Both prolactin and corticosterone collected 1–2 min following ether stress showed a significant linear increase with increasing litter size. The 14-min values of corticosterone were inversely related to litter size. The results are consistent with a prolactin-mediated ‘buffering’ of the corticosterone stress response in the lactatin

ISSN:0028-3835    

DOI:10.1159/000122425

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

28-day-old female rats were killed at increasing time periods after the injection of either 30 IU pregnant mares’ serum (PMS) or saline, and pituitary and plasma luteinizing hormone (LH) and prolactin levels were measured by radioimmunoassay. Hormone concentrations were measured at intervals up to one week following injection with frequent measurements made on the afternoon preceding ovulation to better characterize and evaluate the PMS-treated immature rat as an ovulation model. Peaks in both plasma LH and prolactin occurred on the afternoon preceding ovulation. Pituitary LH was found to decrease and again increase during this afternoon period before falling to a low value on the morning following ovulation. Pituitary prolactin increased to an early afternoon maximum value, fell to a low value by late afternoon, and increased again by the morning following ovulation. Saline-treated immature female rats displayed fluctuations in plasma and pituitary LH and prolactin similar to but smaller than the afternoon changes found in PMS-treated rats. Pituitary weights were significantly greater in PMS-treated rats on the afternoon preceding ovulation. The hormonal changes encountered in the PMS-treated rat prior to ovulation appear to be similar to those encountered in the proestrous cycling female rat, although more study is necessary to validate this system as a model of spontaneous ovulation in the adult animal. The data suggest that PMS causes ovulation in immature rats by amplifying or synchronizing existing hormonal rhythm

ISSN:0028-3835    

DOI:10.1159/000122426

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Blinding and anosmia in male rats is followed by retarded bodily development, reduced weights of the gonads and adnexa, and depressed levels of pituitary luteinizing hormone and prolactin. The effects of dual sensory deprivation are negated, for the most part, by either pinealectomy or the weekly subcutaneous implantation of melatonin (in beeswax). This is the first report that melatonin negates the antigonadotrophìc influence of the rat pineal gland

ISSN:0028-3835    

DOI:10.1159/000122427

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Plasma LH was significantly increased by electrical stimulation of the median eminence (ME) in ovariectomized and in estradiol-treated sheep. In untreated castrates, spontaneous discharges of LH occurred at regular intervals of approximately one hour (LH rhythm). When ME stimulations were initiated as early as 5–15 min following a spontaneous discharge, they increased LH as much as either ME stimulations initiated at other times or spontaneous discharges. These data failed to demonstrate any pituitary refractoriness to ME stimulation, and presumably to endogenous LH-releasing factor (LRF). Therefore, neural mechanisms involving rhythmic release of LRF were indicated. The chronic administration of estradiol inhibited the spontaneous discharges of LH, and subsequent ME stimulation increased plasma LH even more markedly than in untreated castrate

ISSN:0028-3835    

DOI:10.1159/000122428

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Rats subjected to pinealectomy or to pinealectomy plus bilateral superior cervical ganglionectomy exhibited depressed serotonin uptake by hypothalamic synaptosomes; norepinephrine, dopamine or glutamate uptake was not affected by any of the surgical procedures. Treatment with melatonin resulted in inhibition of hypothalamìc serotonin accumulation but it did not modify the uptake of norepinephrine, dopamine or glutamate. These data suggest a relationship between the pineal gland and the serotoninergic nerve endings of the hypothalamus

ISSN:0028-3835    

DOI:10.1159/000122429

出版商:S. Karger AG    

年代:1975

数据来源: Karger