摘要:

The effects of depletion of central nervous system (CNS) catecholamines (CA) upon growth hormone (GH) and prolactin (Prl) secretion were examined in unanaesthetized male rats. Animals were chronically implanted with cannulae for blood sampling and for intracerebroventricular (i.c.v.) injections. GH and Prl secretory profiles were obtained by radioimmunoassay of blood samples drawn every 15 min for a 6-hour period. Hormone profiles were obtained before, 1 day (day 1) and 7 days (day 7) after i.c.v. injection of 6-hydroxydopamine (6-OHDA, total dose 600 μg). GH secretion on day 1 was almost completely abolished (mean GH concentrations 25.2 ± 10.1 vs. baseline 177.2 ± 34.1 ng/ml), but secretory patterns tended to return towards normal by day 7. Prl secretion was markedly increased at day 1 (18.8 ± 5.l vs. 6.7 ± 1.9 ng/ml), but levels had fallen by day 7. Treatment of animals at day 8 with the norepinephrine antagonist phentolamine (7.5mg/kg i.v.) suppressed GH secretion, but stimulated Prl secretion. The administration of the dopamine antagonist butaclamol (1 mg/kg i.v.) on day 9 had no effect on GH secretion, but stimulated Prl release. Histofluorescence examination of tissue sections confirmed extensive disruption of CA structures throughout the CNS. These findings indicate that central CA neurons are facilitatory to GH secretory rhythms, but inhibitory to Prl secretion. Furthermore, it is apparent that the effects of i.c.v. 6-OHDA treatment are transient, recovery being due to re-establishment of functional CA mechan

ISSN:0028-3835    

DOI:10.1159/000123132

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The empty sella syndrome is defined as an intrasellar cisternal herniation in combination with a deformed and/or enlarged sella turcica, but without clinical signs of a pituitary adenoma. In the present study, the impact of the cisternal herniation on pituitary function was analyzed. Special emphasis was placed on the relationship between pituitary function and the size and shape of the sella and type of herniation. The diagnosis of the empty sella syndrome was verified by pneumoencephalography in 49 out of the 50 subjects examined. 15 (30%) exhibited pituitary dysfunction; 10% had panhypopituitarism, 10% isolated secondary hypogonadism with or without hyperprolactinemia, and another 8% hyperprolactinemia alone and 2% had isolated ACTH insufficiency. The observed pituitary disturbances were found in patients who had been examined for a variety of symptoms and were independent of the original reasons leading to radiological examination. Thus, pituitary dysfunction was noted in 6 out of 32 subjects (19%) originally examined for either neurological symptoms or whose sellar enlargement was found accidently. 2 had pituitary insufficiencies and 4 had hyperprolactinemia. These observations stress the importance of thorough evaluation of pituitary function in subjects with empty sella syndrome. Pituitary insufficiency was most often found in subjects with normal-sized sella. A ballooned sella was often observed in patients with normal pituitary function, whereas a deep sella was slightly more common in those with impaired pituitary function. Horizontal herniations were mostly seen in normal-sized sellae and extensive herniations in connection with deep sellae. However, the type of intrasellar herniation was not correlated to pituitary function. Demineralization and erosions of the sella turcica, indicating increased intracranial pressure and signs of disturbed cerebrospinal fluid circulation were seen in half of the patients and could not be related to pituitary function. On the other hand, the occurrence of panhypopituitarism was related to a history of meningoencephalitis or cerebrovascular accidents.

ISSN:0028-3835    

DOI:10.1159/000123133

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Since pulsatile patterns of luteinizing hormone (LH) secretion have been reported in long-term ovariectomized (OVX) rats, but not in intact rats, the patterns of tonic LH secretion were studied in intact female rats and 2, 4 and 8 days after OVX. Blood samples were taken every 10 min for 2 h from intact rats, catheterized the previous day, during the late morning of diestrus-1, proestrus and estrus. Mean LH concentrations were 55 ± 7 ng/ml and did not differ among days. A single increase of circulating LH suggestive of one pulsatile release was seen in 4 of the 14 rats, but no animal showed the regular, repeated increases characteristic of long-term OVX animals. 2 days after OVX, mean LH concentrations were 156 ± 10 ng/ml and patterns characteristic of regular pulsatile releases of LH were seen in 2/6 animals, with occasional pulsatile discharges in another 3. By 4 days after OVX, all 6 animals showed pulsatile patterns of LH, and mean LH concentrations were 190 ± 32 ng/ml. By day 8, mean LH levels had increased significantly, to 357 ± 44 ng/ml, and peak and nadir levels, as well as LH pulse amplitude, had all risen significantly. No significant difference in frequency of LH pulses was noted after OVX, although they seemed to occur more frequently at 8 days. These results suggest that pulsatile discharges of LH in the intact rat are either heavily suppressed or infrequent but that they become a prominent feature of LH secretion soon after

ISSN:0028-3835    

DOI:10.1159/000123134

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The effects of (D-Met2, Pro5)-enkephalinamide – a superactive enkephalin analogue – on the preovulatory discharge of gonadotrophic hormones and on ovulation were investigated. Injection of the opioid (16 nmol) into a lateral cerebral ventricle of regularly cycling female rats immediately before the critical period on the day of proestrus resulted in a blockade of ovulation and in a concomitant depression of the preovulatory plasma luteinizing hormone and follicle-stimulating hormone levels. A smaller dose of the opioid (2 nmol) did not inhibit ovulation. The inhibition of the preovulatory gonadotrophic hormone discharge and the blockade of ovulation by the opioid were reversed by naloxone administration. Our data are consistent with the view that the endogenous opioid peptides may be involved in the physiological regulation of the central neural events which lead to ovulation in the

ISSN:0028-3835    

DOI:10.1159/000123135

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Median eminence corticotropin-releasing factor (CRF) and arginine vasopressin (AVP) and pituitary and peripheral plasma adrenocorticotropin (ACTH) and AVP were measured in male Wistar rats 1 and 2 weeks after bilateral adrenalectomy (ADX), sham operation (SHAM) or dexamethasone-treatment (DEX). Median eminence AVP content was unchanged 1 week after ADX but was significantly elevated 2 weeks after ADX, whereas CRF activity was reduced at 1 week after ADX and returned to control range at 2 weeks. Anterior pituitary ACTH content was elevated but posterior pituitary AVP content was reduced at 1 and 2 weeks after ADX. Plasma ACTH was greatly elevated in ADX rats and reduced in DEX rats, whereas plasma AVP did not differ significantly between these two groups or the control group. When ADX and SHAM rats were laparotomized under ether, plasma ACTH increased greatly, but this elevation was prevented by DEX treatment. The plasma AVP level was elevated in all three groups 2.5 min after onset of stress but returned to the basal range at 20 min. Median eminence CRF and AVP and pituitary ACTH and AVP were not significantly changed after onset of stress. These results indicate that the vasopressin and CRF-ACTH responses were not consistent in the median eminence, pituitary and peripheral plasma and suggest that vasopression is not involved in the feedback and acute stress mechanism of CRF-ACTH secretion. However, we have to measure CRF activity and AVP concentration in the hypophysial portal blood to confirm this conclusion.

ISSN:0028-3835    

DOI:10.1159/000123136

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

A nonhuman primate model was used to evaluate the value of the dexamethasone suppression test as an index of hypothalamic-pituitary-adrenal responsiveness to arousal. In 8 rhesus monkeys plasma cortisol was suppressed by dexamethasone in a dose-dependent fashion at doses between 0.75 and 33 μg/kg. A replication study was performed 5 months later using a single dexamethasone dose (17 μg/kg) known to produce maximal plasma cortisol suppression. This yielded highly correlated results (r = 0.91, p < 0.005) suggesting that dexamethasone suppressibility may be a stable characteristic of individual animals. In 9 other animals whose arousal responses to a stressful procedure (nasogastric tube insertion) had been rated daily over a previous 3-month period, baseline plasma cortisol levels and the percent suppression of plasma cortisol by dexamethasone were evaluated. Baseline plasma cortisol levels did not significantly correlate with the degree of dexamethasone-suppression and the mean arousal ratings within animals. However, the postdexamethasone percent of baseline cortisol did correlate significantly (r = 0.75, p < 0.025) with individual mean arousal ratings. These preliminary results suggest that assessment of the sensitivity of an individual’s hypothalamic-pituitary glucocorticoid feedback system may be a better predictor than its baseline cortisol concentrations of its degree of behavioral arousal to str

ISSN:0028-3835    

DOI:10.1159/000123137

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Primary cultures of dispersed hypothalamic cells were prepared from 18- to 19-day-old rat fetuses. Morphological studies revealed two types of cells having typical glial and neuronal appearances. Immunostaining of cells in culture was positive for neurophysin. The incubation medium contained radioimmunoassayable luteinizing hormone-releasing hormone, vasopressin, β-endorphin and adrenocorticotropin hormone. The present data suggest that hypothalamic cells in primary culture secrete immunoreactive hormones or peptides; however, they do not seem to store significant amounts of these peptides

ISSN:0028-3835    

DOI:10.1159/000123138

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Sulpiride and other benzamides’ displacement of [3H]-spiroperidol binding to rat and dog anterior pituitary dopaminergic receptors was found to be selectively sodium dependent, while typical neuroleptic activity was not influenced by NaCl. These results indicate the existence in the anterior pituitary of a subpopulation of dopaminergic receptors with which benzamides interac

ISSN:0028-3835    

DOI:10.1159/000123139

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The activities of different catecholaminergic neurons in the brains of male and female rats were estimated by measuring the rate of decline of dopamine (DA) and norepinephrine (NE) after inhibition of tyrosine hydroxylase with α-methyltyrosine (α-MT) and the rate of accumulation of dihydroxyphenylalanine (DOPA) after inhibition of DOPA decarboxylase with NSD 1015 in brain regions containing the terminals of these neurons. In the median eminence the accumulation of DOPA and the α-MT-induced decline of DA, but not NE, were higher in the female than in the male, suggesting increased activity of tuberoinfundibular DA neurons in the female. There were no sexual differences in DA neurons which terminate in any of the other brain regions (striatum, olfactory tubercle, nucleus accumbens, posterior pituitary). To determine if the sexual difference in tuberoinfundibular DA neuronal activity results from neonatal exposure to androgens, the rate of DOPA accumulation was examined in the median eminence of females, males, and androgen-sterilized females (all of which were castrated as adults) and in adult males which were castrated as neonates. Similar values for DOPA accumulation were observed in the median eminence of castrate females and neonatally castrated males, while significantly lower values were observed in castrate males and androgen-sterilized females. Thus, neonatal exposure to androgens alters the activity of tuberoinfundibular DA neurons. Neonatal androgen-induced differences in tuberoinfundibular DA neuronal activity may be responsible, in part, for sexual differences in the hypothalamic regulation of hypophyseal hormone secreti

ISSN:0028-3835    

DOI:10.1159/000123140

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

These studies investigated the effect of aging on thyroid hormone regulation of β-endorphin in rat corpus striatum and hypothalamus. In both brain areas, basal levels of β-endorphin declined with age. In addition, age modified the response of β-endorphin to thyroid hormone status. Hypothyroid rats aged 6 months (mature) exhibited a 67% mean decline in the level of β-endorphin in the corpus striatum. Hypothyroid rats aged 20–24 months (senescent) exhibited no change in the level of β-endorphin in the corpus striatum. Hypothyroid rats aged 6 months had a 28% mean decline in the level of hypothalamic β-endorphin. There was no change in hypothalamic β-endorphin content in hypothyroid senescent rats. Hyperthyroidism resulted in elevations of β-endorphin in both the corpus striatum and hypothalamus in senescent, but not mature rats. Changes in β-endorphin seen with age are at least in part thyroid hormone dependent. In addition, age is capable of modifying the response of brain tissue to thyro

ISSN:0028-3835    

DOI:10.1159/000123141

出版商:S. Karger AG    

年代:1981

数据来源: Karger