ISSN:0028-3835    

DOI:10.1159/000122347

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Statistically significant diurnal variations in plasma growth hormone (GH) were found to occur in handled male rats. Peak GH values (at midday) appeared to be inversely correlated with the diurnal peak of plasma corticosterone (CS) which occurred after the onset of darkness. Brain amines were examined in the following regions: cortex, striatum, septum, amygdala, pons, midbrain, and hypothalamus. Statistically significant diurnal cycles of serotonin (5-HT) concentration were found in the amygdala and midbrain, while an ultradian cycle of 5-HT was present in the striatum. Striatum and pons also showed significant diurnal alterations in norepinephrine (NE) levels. Ultradian dopamine (DA) cycles were significant in all regions examined. Plasma GH changes were found to be directly correlated with midbrain and amygdala 5-HT levels and with DA levels of all areas except the amygdala. Plasma CS was found to be inversely correlated with striatal and cortical DA and with 5-HT levels of amygdala.

ISSN:0028-3835    

DOI:10.1159/000122348

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Changes in antidiuretic substance (i.e., vasopressin) release from the cut pituitary stalk and the intact pituitary gland were observed during electrical stimulation of amygdala medial nucleus. Electrical pulses of 4 or 36 cycles per second (cps) were used and in both cases the same energy (about 2.160 nanowatt seconds) per 1.5-sec train of electrical pulses remained constant. Antidiuretic substance release from the hypothalamic end of the cut pituitary stalk and from the intact pituitary gland increased during the 36-cps electrical stimulation of amygdala medial nucleus, however the 4-cps electrical stimulation of this structure did not produce any changes in these processes. The results obtained indicate that the medial nucleus of amygdala is able to change the function of the hypothalamo-hypophysial system and can be motivated with high frequency stimulating pulses.

ISSN:0028-3835    

DOI:10.1159/000122349

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Plasma TSH responses after an i.v. injection of 100 mg of L-dopa were evaluated by radioimmunoassay in 4 normal euthyroid subjects and in 8 patients with primary hypothyroidism. In agreement with previous results, no variations in plasma TSH levels were observed in the euthyroid subjects. In contrast, in primary hypothyroidism L-dopa induced a biphasic response in plasma TSH. In fact, we observed a transitory increase with a maximum at 30 min (mean ± SEM = 54 ± 18%) followed by a decrease reaching a minimum level of plasma TSH basal values at 90 min (mean ± SEM = 15 ± 6%). These findings demonstrate that the plasma TSH response to L-dopa in primary hypothyroidism is time-dependent. Some speculation on the possible mechanism of this action is presen

ISSN:0028-3835    

DOI:10.1159/000122350

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

It has previously been shown that stimulation of an adrenergic system in the central nervous system (CNS) will depress the increase in plasma corticosterone (B) following surgical stress. Two aspects of hypothalamo-pituitary-adrenal function, namely adrenal compensatory hypertrophy (ACH) and plasma B response to ether stress, were studied to determine the influence of this adrenergic component. Phenoxybenzamine, an α-adrenergic blocking agent, chronically implanted into the lateral ventricle produced an augmented response to ether stress, whereas norepinephrine (NE), dopamine (DA), and propranolol did not. The augmented response was similar to that observed following the daily administration of reserpine (0.25 mg/kg, s.c). The response to this dose of reserpine was blocked by the simultaneous administration of a low dose of dexamethasone (14 µg/kg, s.c). Augmentation of the stress response was not produced by larger doses of reserpine but did occur with lower doses. The effects of the treatments on ACH were not consistent with those observed on the stress response, suggesting that different mechanisms are involved. The data support the concept of an α-adrenergic component in the CNS which serves to inhibit the plasma B stress respon

ISSN:0028-3835    

DOI:10.1159/000122351

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Adult Charles River female rats were pinealectomized, sham-operated or left intact, and half of each group was placed in 12L:12D while the other half was exposed to constant light (LL). Daily vaginal smears permitted the calculation, at weekly intervals, of the percent of rats in each group in LL showing 5 or more consecutive days of vaginal cornification. After 11 weeks in LL, those rats were returned to LD for 6 weeks and then put back into LL until the termination of the experiment 3 weeks later. Pinealectomized, sham-operated and intact animals developed persistent estrus (PE) in LL at the same rate, began recycling at the same rate when returned to LD, and again went into PE at the same rate when put back into LL. Confirming our earlier observations, pinealectomized rats in 12L:12D showed significantly fewer 4-day cycles (or more 5-day cycles) than did intact rats in the same photoperiod. Body and organ weights and serum LH levels showed no differences attributable to pinealectomy. It is concluded that the pineal is not influential in the induction of PE in LL, but its apparent role in controlling cycle length in shorter photoperiods is confirmed.

ISSN:0028-3835    

DOI:10.1159/000122352

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Multiple-unit activity (MUA) was obtained from neuronal pools in the gonadotropic hypothalamus of quails. A special device allowed for exploration of various hypothalamic structures in unanesthetized birds. All recording sessions were made in the dark. Spontaneous and flash light-evoked MUAs were recorded from both tuberal and dorsal gonadotropic areas, either in the morning or in the afternoon, and were compared to extragonadotropic firing patterns. Firing rates (spikes/10 sec) and integrated MUA (200 addresses) provided distinctive spontaneous neuronal activities for various cell clusters. These spontaneous salient features appeared to be changeable throughout the photoperiod. Flash stimulations resulted in a marked increase in MUA recorded from the gonadotropic regions of the hypothalamus.

ISSN:0028-3835    

DOI:10.1159/000122353

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

The effect of castration upon hypothalamic LH-RF synthesis and content was determined in mature male rats. In each single experiment 20 hypothalami from both normal and 60-day-castrated rats were bisected into symmetrical portions. For the determination of LH-RF synthesis 20 hypothalamic halves were incubated for 120 min. After incubation the tissue was homogenized in medium containing 1 Nacetic acid, and centrifuged; 1.0 ml of the supernatant was used to test LH-RF activity. In the other 20 halves, hypothalamic LH-RF content was determined: the samples were homogenized without incubation in 1 Nacetic acid, centrifuged, and LH-RF activity was tested in 1.0 ml of the supernatant. LH-RF activity was determined in vivo in ovariectomized rats pre-treated with estrogen-progesterone by measuring, by radioimmunoassay, the LH modifications in serum after the i.v. administration of the extracts. Hypothalamic LH-RF content was significantly higher in control than in castrated rats (p < 0.001). After incubation there were no changes in the LH-releasing potency of control hypothalami compared with non-incubated tissue, whereas a significant increase (616%) was found after the incubation of hypothalami from castrated rats. On the other hand, after incubation LH-RF activity was higher (p < 0.02) in castrated than in control hypothalami. These results suggest that castration stimulates the release and synthesis of hypothalamic LH-RF in male rats.

ISSN:0028-3835    

DOI:10.1159/000122354

出版商:S. Karger AG    

年代:1975

数据来源: Karger