摘要:

Normal and castrated male rats implanted with permanent right atrial cannulae were used, and sequential blood samples were taken every 2 min through the cannula. When the rats, both normal and castrated, were exposed to ether for 2 min, the prolactin (Prl) concentration in plasma was immediately and dramatically elevated. During 40 min of continuous ether anesthesia, plasma Prl concentration was not sustained. After the initial ‘surge’ of Prl secretion, which lasted about 15 min, the concentration returned to normal levels. Following the peak of the Prl ‘surge’, Prl disappeared from the circulation with a calculated half-life of 7 min (mean value: 6.9 min; confidence interval: 6

ISSN:0028-3835    

DOI:10.1159/000122826

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Serum hormone levels of blood collected within 1 min by cardiac puncture following ether anesthesia were compared to those of blood collected by decapitation in male rats 30, 60, and 90 days of age. Neither testosterone (T) nor LH was affected by the method of blood collection. Serum FSH was significantly elevated in blood collected by cardiac puncture, and 30-day old rats were the most sensitive to this effect. Serum prolactin (Prl) was significantly elevated in all age groups when blood was collected by cardiac puncture. Both blood-collecting methods demonstrated that, in the 3 ages tested, serum T increased with age, LH and FSH decreased with age, and Prl did not change with age, indicating that blood collection by cardiac puncture is as valid a method as is decapitation for assessing serum hormone levels during maturation.

ISSN:0028-3835    

DOI:10.1159/000122827

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

To delineate the pattern of adenohypophyseal hormone secretion following chronic stress, adult male rats were exposed daily to 6 h of cold, forced exercise or immobilization for 3, 6, 10, 15, 28 or 42 consecutive days. Groups of these animals were sacrificed at the end of the last stress sessions, and plasma growth hormone (GH), luteinizing hormone (LH), prolactin (Prl) and follicle-stimulating hormone (FSH) levels were measured by radioimmunoassay (RIA). Irrespective of the different stimuli used, long-term stress induced a morphologic and hormonal response characterized by decreased ponderal growth, adrenal enlargement, thymus involution and significant diminutions in GH, Prl and LH levels with no modifications in FSH titers. The magnitude and duration of these changes varied with the severity of the stressors.

ISSN:0028-3835    

DOI:10.1159/000122828

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Rats were injected with monosodium 1-glutamate (MSG) daily for the 1st 5 days of life and allowed to mature. This is known to cause selective destruction of neurons in the retina and in the arcuate nucleus of the hypothalamus. The adult animals had a significant increase in body fat without an increase in weight, a marked reduction in pituitary, thyroid, adrenal, gonadal and prostate weights. Pituitary, hypothalamic and serum thyrotropin (TSH) were significantly reduced in the males. Serum growth hormone (GH) was markedly reduced in both sexes and the serum prolactin (Prl) was increased significantly in females. FSH did not appear to be abnormal and the LH may have been increased in the males. Serum T4 was significantly reduced in females. The fertility of the females was normal, but treated males mated with normal females showed a marked reduction in fertility and, although the litter sizes of the offspring were normal, the birth weights of the pups of both sexes were significantly reduced. These persistent alterations in neuroendocrine function indicate that lesions produced by neonatal MSG treatment provide a convenient model for studying hypothalamic function.

ISSN:0028-3835    

DOI:10.1159/000122829

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The effects of hypothalamic deafferentation on the estrous cycle and ovulation were studied in the mature female guinea pig, a spontaneous ovulator with a true luteal phase. Animals were stereotaxically deafferentated using the Halász knife technique. (1) Large complete deafferentation of the medial basal hypothalamus (MBH; arcuate nucleus, median eminence (ME), and a ventral part of the ventromedial nucleus) did not block cyclic ovulation, although the cycle became slightly prolonged. (2) Small complete deafferentation which excluded the ventromedial nucleus from the MBH and partially damaged the arcuate nucleus and ME resulted in anovulation and constant closure of the vaginal membrane. (3) Large anterior deafferentation, which eliminated neural afferent from medial preoptic area (MPO), suprachiasmatic portion of the preoptic nucleus (POSC) and the anterior periventricular area to the MBH, was effective in blocking ovulation and inducing constant vaginal opening. In most of the cases, the knife passed rostral to the suprachiasmatic nucleus (SCN). (4) Small anterior deafferentation at the caudal border of the optic chiasma did not block ovulation if the arcuate nucleus and ME were intact, although the cycle sometimes became irregular. (5) Posterior deafferentation at the level of the mammillary bodies failed to interfere with cyclic ovulation. It is concluded that, in the guinea pig, the deafferentated MBH is capable of sustaining both tonic and phasic secretion of gonadotropins (Gns) necessary for maintenance of normal estrous cycles and ovulation. However, this function of the MBH may also be modulated by facilitatory and inhibitory influences arising from extrahypothalamic areas

ISSN:0028-3835    

DOI:10.1159/000122830

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The effects of thyrotropin-releasing hormone (TRH) on growth hormone (GH) and prolactin (Prl) secretion have been investigated in vitro and in vivo in domestic fowl. In both conscious and anaesthetized immature chickens the administration (i.v.) of TRH (2.5 and 25 μg/kg) significantly increased the concentration of plasma GH. The simultaneous administration of somatostatin (GHRIH), 2.5 μg/kg, to conscious birds significantly reduced the magnitude of the GH response to TRH treatment, but had no effect on the basal levels of plasma GH. The repeated injection of TRH (10 μg/kg) every 20 min over a 100-min period failed to maintain the concentration of plasma GH at a high level. Prl secretion was not stimulated in any of these experiments, and in anaesthetized birds TRH (2.5 and 25 μg/kg) treatment was followed by a depression in the level of plasma Prl. The effects of TRH and GHRIH on GH secretion by an in vitro dispersed pituitary cell suspension system were very similar to the in vivo studies. TRH stimulated Prl release in vitro, in contrast to the in vivo studies, and the response was dose related. GHRIH had no effect on the basal release of Prl in vitro but significantly inhibited the response to TRH treatm

ISSN:0028-3835    

DOI:10.1159/000122831

出版商:S. Karger AG    

年代:1978

数据来源: Karger