摘要:

Release of antidiuretic substance (vasopressin) from the central end of the cut pituitary stalk and the urine flow rate were estimated during electrical stimulation of the CA1 field of the left hippocampus in rats. Frequencies of 4, 12, or 36 c/sec were used for hippocampal stimulation during the collection of the antidiuretic substance released from the cut infundibular axons, and frequences of 4 or 36 c/sec were used for hippocampal stimulation during urine flow determination. In all experiments, the current and voltage were adjusted to obtain approximately the same energy per train of pulses (2,160 nanowatt seconds). The antidiuretic activity of the fluid washing the cut pituitary stalk decreased during 4 c/sec hippocampal stimulation, showed no significant change during 12 c/sec stimulation, and increased considerably during 36 c/sec stimulation. The rate of urine flow did not alter during hippocampal stimulation at 4 c/sec, but decreased markedly during 36 c/sec stimulation. It is assumed that the hippocampus is able to trigger an increase or decrease in the rate of axoplasmic flow of antidiuretic substance and in the release of antidiuretic hormone from the pituitary gland. The frequency of hippocampal stimulation determines the response when the energy per train of electrical pulses remains constant.

ISSN:0028-3835    

DOI:10.1159/000122227

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

Female rats maintained on a 23 h water deprivation schedule show an altered circadian rhythm of pituitary-adrenal activity. Significant elevations of plasma corticosterone are observed in the morning if the watering time is between 1000 and 1100 h. These elevations continue to early afternoon if watering occurs at 1500 h. The normal late afternoon peak is abolished. Different patterns of adrenocortical rhythms are observed when the watering time is shifted from morning to afternoon.

ISSN:0028-3835    

DOI:10.1159/000122139

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

Male rats treated postnatally witha single intraventricular injection of 10 µg of 6-hydroxydopamine (6-OHDA) exhibited a sig-nificant increase in pineal hydroxyindole-O-methyl transferase (HIOMT) activity on the 30th day of life; female animals failed to display changes in the pineal enzyme. 6-OHDA depressed hypothalamic norepinephrine levels in both sexes. Neonatal castration abolished the pineal response to postnatal 6-OHDA in males, while concurrent treatment with both testosterone and 6-OHDA caused pineal HIOMT activity to increase in females. Since the 10 µg dosage of intraventricular 6-OHDA probably acted in a selective manner upon catecholamine-containing neurons within the brain, our observations suggest that androgens acted upon these neurons early in life to cause long-term changes in the central control of pineal function. Higher intraventricular doses (50 and 100 µg) of 6-OHDA caused corresponding decreases in pineal HIOMT activity among both male and female animals killed at 30 days of age, probably because the drug damaged peripheral sympathetic nerve terminals within the pineal organ itself. None of the experimental regimens used in this study altered the HIOMT activity of the reti

ISSN:0028-3835    

DOI:10.1159/000122140

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

In 16-day-old rat fetuses, the pars an-terior of the hypophysis consisted only of agranular primordial cells. In newborn rats, the pars anterior contained numerous agranular and granular cells, which were classified into three types (thyrotrophs, gonadotrophs of FSH-type, and somatotrophs) on the basis of the appearance of the secretory granules in their cytoplasm. In fetal rats in which encephalectomy had been performed on the 16th day of gestation, the hypophysis was abnormally small at the time of parturition, but the pars anterior, like that of normal newborn rats, contained many agranular cells and three types of granular cells. The secretory granules of these cells were smaller and fewer in number than those in normal neonates. The hypophysis of 60-day-old rats subjected to neonatal hypophysial stalk transection contained many mammotrophs as well as other granular cells (thyrotrophs, gonadotrophs of FSH-type, and somatotrophs). In these animals, the cells of the pars anterior were small, and their secretory granules were smaller and fewer in number than those in normal adults. In harmony with the atypical morphological appearance of the secretory cells in the pars anterior, such animals exhibited severe retardation in body growth, and in gonadal and thyroid development. These findings suggest that primordial agranular cells of the pars anterior are able to differentiate into granular cells in the absence of hypothalamic control, but that hypothalamic mediation is required for full maturation of granular cells.

ISSN:0028-3835    

DOI:10.1159/000122141

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

Sex difference in the circadian periodicity of thehypothalamic content of corticotropin-releasing factor (CRF) was examined in the rat. The CRF content in the female hypothalamus was higher in the morning than in the afternoon. In contrast, in the male rat under similar experimental conditions, the CRF content was higher in the afternoon than in the morning. In the female rat, a peak value of CRF content was found at 8 a.m. and a precipitous fall ensued around noon, with a concomitant sharp rise of plasma cortico-sterone levels. Ovariectomy reduced the morning levels without raising the afternoon levels, the peak value occurring at noon. Cervical ganglionectomy did not essentially affect the basic pattern of the circadian rhythm of CRF content in the female rat. These results indicate that there is a marked sex difference in the manifestation of circadian rhythm of hypothalamic CRF content, that is, the pattern of circadian rhythm in the female rat is the reverse of that found in the male rat. The rapid fall of hypothalamic CRF content around noon in the female rat always accompanies a sharp rise of the plasma corticosterone; thus, the whole pattern of changes of CRF content during a 24 h period is a mirror image of that of plasma corticosterone.

ISSN:0028-3835    

DOI:10.1159/000122142

出版商:S. Karger AG    

年代:1973

数据来源: Karger