摘要:

A Golgi-Cox study of the supraoptic nucleus of the adult rabbit has revealed the presence of three major cell types: (1) large multipolar neurons; (2) large bipolar neurons, and (3) small interneurons. The multipolar and bipolar neurons demonstrated regional variation in the rostral and caudal aspects of this nucleus, while the interneurons appeared identical throughout the nucleus. This study provides detailed cytoarchitectural descriptions of the magnocellular neurosecretory cells in the supraoptic nucleus and establishes the presence of an interneuronal cell population through which incoming afferent messages could influence the neurosecretory neurons.

ISSN:0028-3835    

DOI:10.1159/000122926

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Methanol extracts of several rat tissues (hypothalamus, amygdala, the rest of the forebrain, brain stem and pancreas) were partially purified in SP-cation exchange chromatography and measured in TRF radioimmunoassay. It was found that hypothalamic and amygdaloid TRF contents were highest during the light period of the day, but brain stem TRF had an opposite rhythm. Hypothalamic TRF content rose after 10 min by 14% (p<0.05) when the rats were exposed to transfer stress. During short-time immobilization stress tests, hypothalamic TRF rose by 41% (p<0.05) after a 10-sec immobilization. Cold exposure did not produce any changes in hypothalamic TRF contents within 45 min. Handling stress and time of day appear to be the most important factors influencing the hypothalamic TRF content and have to be taken into account when measuring TRF.

ISSN:0028-3835    

DOI:10.1159/000122927

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Tissue distributions of radioactivity were studied at 2, 4 and 6 h after intravenous injection of 3H-estradiol-17/J (48.6 ng/100 g b.w.) in 4 groups of 10 or 11 adult female rats with the following neonatal treatments: Control = sham ovariectomy (ovx) on day 1, oil injection on day 5 (n = 10); ovx = ovx on day 1, oil on day 5 (n = 11); TP = sham ovx on day 1, 30 μg testosterone propionate (TP) on day 5 (n = 10); ovx-TP = ovx on day 1, 30 μg TP on day 5 (n = 11). Neonatal TP treatment significantly hastened vaginal opening in all animals. After ovariectomy, vaginal opening occurred in 20/22 rats regardless of hormonal treatment; ovariectomy did not significantly affect the time of vaginal opening in these 20 animals. All ovariectomized animals had diestrous vaginal smears after puberty, all controls cycled normally and all of the TP group used for the uptake part were in persistent vaginal estrus (sequence of vaginal smears with 70% or more containing no leukocytes) confirmed by ovarian histology to be anovulatory (11/13 injected). 72 h prior to radioisotope injection, intact females in the above groups were ovariectomized and the neonatally ovariectomized were sham operated. Tissue radioactivity was extracted from the anterior, middle and posterior hypothalamus, hippocampus, amygdala, cerebrum, anterior pituitary, uterus and plasma. Neonatal ovariectomy raised 3H-estradiol concentrations in all tissues, except hippocampus and anterior pituitary, suggesting an increase in nonspecifically bound hormone. Neonatal TP decreased 3H-estradiol concentrations in the anterior and middle hypothalamus and uterus only, in both the intact and ovariectomized group, demonstrating a selective effect of neonatal TP upon subsequent development of estrogen binding capacities of target tissues that is independent of the ovarie

ISSN:0028-3835    

DOI:10.1159/000122928

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The results of several studies imply that estrogen can act upon the central nervous system via a protein synthetic step. Our objective was to determine if the intrahypothalamic (preoptic area, POA) injection of cycloheximide (CHX), an inhibitor of protein synthesis, at 17.00 h on diestrus II of the 4-day cycle altered lordotic behavior and (or) ovulation in the intact rat (sexual receptivity to males normally begins on the evening of proestrus as herein defined; ovulation occurs on estrus of the cycle). CHX-treated females were tested for lordotic behavior at 23.00 h on proestrus, then killed at 17.00 h on the following day. None of the CHX-POA rats were receptive to the males and 90% of these rats did not ovulate. Thus, CHX significantly suppressed sex behavior and ovulation in the cyclic rat.

ISSN:0028-3835    

DOI:10.1159/000122929

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The incidence of senescent anovulation (constant estrus) in female rats increases sharply in the age interval 10-14 months. We have compared the neuroendocrine status of 12-month-old rats, which were still cycling, with that of 6-month-old rats in the reproductive prime. Norepinephrine content in the median eminence of the hypothalamus and circulating levels of FSH and androstenedione were significantly higher in middle-aged rats (12 months old) than in young controls (6 months old). These increases were selective, in that ten other neuroendocrine parameters measured were unchanged. These results indicate that changes occur at multiple levels of the neuroendocrine system during the transitional phase prior to the onset of senescent anovulation.

ISSN:0028-3835    

DOI:10.1159/000122930

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Immobilization stress had a biphasic effect on serum prolactin levels: the early short stimulatory phase followed by a long inhibitory phase in male rats. Stress induced the rise in serum prolactin without concomitant increase in serum TSH levels which declined during the immobilization for 300 min. Other stressors, ether inhalation or formalin s.c. injection, or TSH i.v. injection, which were effective in controls failed to elevate serum prolactin after the 300-min immobilization. Serum TSH responded to TRH after the stress as well. Pimozide, dopamine receptor blocker, was effective in increase of serum prolactin in the stressed rats as well as in controls. In pimozide pretreated rats, elevated serum prolactin levels decrease in 10 min by the immobilization and returned to the preimmobilization levels thereafter which were higher than those in stressed animals without pimozide treatment. It is suggested that TRH is not a physiological PRF in the stress-induced prolactin release and that the dopaminergic system may be activated by the immobilization stress, resulting in decrease of the prolactin-releasing activity of the pituitary.

ISSN:0028-3835    

DOI:10.1159/000122931

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Unrestrained, freely moving rats implanted with an atrial indwelling cannula were used to inject estradiol and to take blood samples. The effect of estradiol on prolactin secretion was monitored by taking blood samples every 2 min. When a single bolus of estradiol (100 μg/kg) was injected, no response was seen for approximately 2 h. There then followed a pulsatile pattern of plasma prolactin and this lasted more than 24 h. The elevation of the prolactin concentration was not accomplished by a gradual change but through frequent pulsatile bursts of secretion. The major slopes of the decay curves of these bursts, plotted on a semilogarithmic scale, were parallel to a theoretical curve with a slope of 7 min half-life. Such consistency of decay slopes indicates that prolactin secretion is accomplished through discrete bursts of secretion

ISSN:0028-3835    

DOI:10.1159/000122932

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The short-term effect of the mechanical lesion of the organum vasculosum of the lamina terminalis (OVLT) was investigated in 4-day cycling female rats. The lesions were performed on the 2nd day of diestrus, and the animals were killed by decapitation 30 h after the lesion. Serum LH, FSH and prolactin and hypothalamic LH-RH content of 3 different parts of the hypothalamus were determined with radioimmunoassay. OVLT lesion caused a significant increase in the LH-RH content of the mid-basal hypothalamus and in serum prolactin levels and a decrease in LH and FSH serum levels. The results support the view that the OVLT may play a role in the control of pituitary gonadotrophic hormone secretion.

ISSN:0028-3835    

DOI:10.1159/000122933

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

A significant diurnal variation in α-melanocyte stimulating hormone (α-MSH) concentrations was observed in discrete regions of the rat brain. During the 12 h light: 12 h dark cycle, α-MSH concentrations in each case were highest during the light period and lowest during the dark period. At 09.00 h, 3 h after lights were turned on, the peak α-MSH concentration occurred in the median eminence, the arcuate and dorsomedial hypothalamic nuclei and the periventricular thalamic nucleus. The paraventricular and anterior hypothalamic nuclei had highest α-MSH concentrations at 13.00 h. In the medial preoptic nucleus, the peak α-MSH concentrations appeared at 17.00 h. These changes in α-MSH content may reflect an α-MSH role in circadian variations in behavioral and neuroendocrine pr

ISSN:0028-3835    

DOI:10.1159/000122934

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The effects of morphine (M) and naloxone (N) on serum levels of luteinizing hormone (LH) and prolactin (PRL) in prepubertal male and female rats were investigated. N raised serum LH concentrations in female rats at 10, 15, 20, 25 and 30 days of age, but increased serum LH levels in male prepubertal rats only at 30 days of age. M significantly depressed serum LH values in both sexes only at 15 days of age. M increased serum PRL levels in immature rats of both sexes in all age groups, except in 25-day-old males, whereas N decreased serum PRL only in 25-day-old male rats. These data show that there are differences in the pituitary LH and PRL responses to M or N of immature as compared to the responses previously reported in mature rats, and suggest that the endogenous opioid peptides may have a role in regulating LH and PRL secretion in immature rats.

ISSN:0028-3835    

DOI:10.1159/000122935

出版商:S. Karger AG    

年代:1979

数据来源: Karger