摘要:

The present study deals with the effect of vaginal stimulation (VS) with a glass rod on unit activity in the brain and the correlation of the activity of each area under certain hormonal conditions. The frequency characteristics of the neuronal discharges in the brain stem, limbic structures, and hypothalamus were recorded, using stereotaxically oriented steel micro-electrodes, in adult female rats under light urethane anesthesia. The following results were obtained: (1) The level of ‘spontaneous’ activity in the anterior hypothalamic, preoptic, and septal areas of estrogen-primed spayed rats was higher than that observed in ovariectomized, non-estrogen-primed rats. (2) Significant and discriminated responses induced by VS were observed only in the estrous state, that is, after estrogen priming in the case of the ovariectomized animals. (3) These responses were almost independent of the EEG activity level, and could be discriminated from the response to other peripheral stimuli such as pinching. (4) The firing rate of hypothalamic neurones, depending on their locations, increased or decreased during and only immediately after VS (‘phasic response’), by means of which the EEG after-reaction was induced. Reciprocal changes were observed between the periventricular arcuate nucleus (ARC) (facilitated) and ventromedial hypothalamus (VMH) (inhibited), and between the basal and medial parts of the anterior hypothalamic area (AHA) (inhibited) and the medial preoptic area (MPO) (facilitated). (5) Neurone activity in the ventromedial part of the midbrain reticular formation (MRF), in the dorsal hippocampus (DHPC), in the medial complex of the amygdala (AMYG) and lateral septum, was enhanced during and for some minutes after VS (‘tonic response’), with the appearance of the EEG after-reaction. (6) The MRF may play a significant role in discriminating vaginal impulses from other peripheral sensory afferents. Interrelations of the unit activity in the above portions of the brain in estrogen-primed rats were examined by electrical stimulation and the results were as follows: (1) The VMH and ARC nuclei were reciprocally interrelated, and there exists an inhibitory pathway between them that may subserve changes in functional activity. (2) Electrical stimulation of the MPO and the AHA decreased unit activity of the VMH and increased that in the ARC. (3) The cornu ammonis of DHPC and the medial complex of the AMYG had a reciprocal relationship with the hypothalamus. In other words, the DHPC increased AHA activity and decreased MPO activity, while the AMYG influenced these nuclei conversely. Similarly, the DHPC increased and the AMYG decreased unit discharge in the ARC, while they exerted a reverse influence on the VMH activity. It is therefore suggested that the DHPC mainly activates the AHA-ARC circuit and the medial AMYG activates the MPO-ARC circuit, while both the hippocampus and amygdala may participate in different functional reorganizations activated by resp

ISSN:0028-3835    

DOI:10.1159/000121985

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

In adult male rats, the 5-HT content of the hippocampus and the amygdala was found to exhibit a diurnal rhythm, with the lowest value at 0400 and the highest at 2000 h. The diurnal curve of plasma corticosterone generally parallels the 5-HT content, with the lowest value at 0800 and the highest at 2000 h. PCPA, 300 mg/kg 72 and 48 h before sacrifice, was found to increase the a.m. and decrease the p.m. plasma corticosterone values, so that the level remained relatively constant throughout the day. At both 0800 and 2000 h, the PCPA produced a 50–63 % reduction in the 5-HT content of the amygdala, hippocampus, and hypothalamus. The results suggest that ‘serotoninergic’ neurons play a role in the diurnal fluctuation in pituitary-adrenal fun

ISSN:0028-3835    

DOI:10.1159/000121956

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

The α-adrenergic blocking agent, phenoxybenzamine, was found to have no effect on the increase in renin secretion produced by stimulation of the ‘pressor area’ of the medulla oblongata in dogs. The β-adrenergic blocking agent, propranolol, reduced the response when administered at two different dose levels. Administration of propranolol plus phenoxybenzamine completely abolished the increase. The data are consistent with the hypothesis that renin secretion is controlled, at least in part, by β-adrenergic receptors in the

ISSN:0028-3835    

DOI:10.1159/000121957

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

Restricting male rats to one-half normal food intake from day 25 until day 60 of life significantly delayed all aspects of normal growth that were measured. Body weights were reduced by 50% and pituitary growth hormone (GH) and plasma GH levels were severly reduced compared with corresponding values of ad libitum controls. Underfeeding also partially inhibited testicular and accessory organ growth. If underfeeding was combined with blinding, a more marked inhibition of testicular and accessory organ growth occurred. The effect of combining blinding and underfeeding was more dramatic than the effect of each treatment independently, indicating an accentuation of the response with the combination of treatments. This marked lag in development of the reproductive organs of blinded underfed rats was apparently mediated by the pineal gland, since blinded-pinealectomized underfed rats had reproductive organs that were considerably larger than those of blinded underfed rats.

ISSN:0028-3835    

DOI:10.1159/000121958

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

The present study was undertaken to determine the site(s) of action of the suckling stimulus in the hypothalamus and involvement of the cholinergic link in the milk-ejection reflex, by using systemic administration and intracerebral implantation of atropine in lactating rats. Atropine administered subcutaneously blocked the milk-ejection reflex almost completely at dose levels of 700 or 350 mg/kg body weight. Implants of atropine in the paraventricular nucleus blocked the milk-ejection reflex in all 5 animals used. The mammary glands of 4 out of 5 animals were filled with milk for 3 days after the operation. The blockade of the milk-ejection reflex in the rats implanted with atropine in the paraventricular nucleus was overcome by the injection of oxytocin. These results suggest that the paraventricular nucleus is concerned with the regulation of the milk-ejection reflex and that the neural relay might be of a cholinergic nature. Implants of atropine in the median eminence and the arcuate nucleus caused blockade of the milk-ejection reflex in 5 out of 6 animals. However, since milk accumulation following the operation was not found in 4 animals of this group, the cholinergic link in the median eminence may also affect milk secretion in the rat.

ISSN:0028-3835    

DOI:10.1159/000121959

出版商:S. Karger AG    

年代:1971

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000121960

出版商:S. Karger AG    

年代:1971

数据来源: Karger