摘要:

Intracranial implants of estradiol benzoate (EB) were used to explore sites of action for the activation of masculine copulatory behavior in castrated male rats. In experiment 1, 27 or 30 gauge implants were placed unilaterally throughout the hypothalamus and preoptic area. Dihydrotestosterone (DHT) was administered subcutaneously (s.c.) to each male. 25 of 42 males with EB implants located in the medial anterior hypothalamic-preoptic area (AHPOA) exhibited ejaculatory patterns on at least 40% of the post-implantation tests. In contrast, only 4 of 18 of the males with implants located posterior to the anterior hypothalamic area displayed this level of response. This difference in the proportion of animals responding for each implant group was statistically significant. Seminal vesicle weights were not correlated with the occurrence of copulation. In experiment 2, either EB-filled or empty cannulae were placed unilaterally in the AHPOA. Half of the males of each group also received DHT s.c. Intracranial EB in conjunction with DHT s.c. resulted in a significantly greater frequency of ejaculatory response than any other treatment. Despite significant differences among the groups in seminal vesicle weights, there was no correlation with occurrence of ejaculatory behavior. These results are consistent with the hypothesis that testosterone (T) exerts its effects upon masculine sexual behavior via conversion to estradiol (E2); and that the principal neural site of action is the AHPOA.

ISSN:0028-3835    

DOI:10.1159/000122865

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The effects of intracerebral estradiol benzoate (EB) implants upon lordosis behavior in castrated male rats were investigated. 27 gauge EB-filled or Blank implants were placed unilaterally in either the preoptic area (POA) or the region of the ventromedial hypothalamic nucleus (VMH). When 0.5 μg of EB was administered subcutaneously for eight days, males with EB implants had significantly higher lordosis quotients (LQ) than males with Blank implants. EB implants located in the region of the VMH were significantly more effective in stimulating lordosis responses than implants in the POA. These results indicate that, in male rats as in females, the VMH region is a primary site for the hormonal activation of lordosis behavior

ISSN:0028-3835    

DOI:10.1159/000122866

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Direct placement of L-dopa into the medial preoptic area (MPOA) of aged pseudopregnant or constant vaginal estrous female rats resulted in a reinitiation of vaginal cycles and ovulation. Similar treatment with L-dopa in the dorsomedial septum or cortex was ineffective. Direct placement of leucine into any of the three brain regions did not have an effect on ovarian function. Intermittent treatment with L-dopa to MPOA was found to reinstate and maintain vaginal cycles in constant estrous females only when administered on the day of vaginal estrus of successive cycles. These findings support the hypothesis that age-dependent disturbances in ovarian function may be initiated by changes in neurotransmitter metabolism within the central nervous system.

ISSN:0028-3835    

DOI:10.1159/000122867

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Morphine (50 mg/kg), given at 12:00 h and 14:00 h to proestrous rats, completely inhibited the proestrous surges of serum luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin (Prl). However, when it was given at 16:00 h, the inhibitory effect of morphine (Mor) was decreased. Pethidine and nalorphine inhibited the proestrous surges, while pentazocine showed a weaker inhibitory effect. Naloxone (Nx), given simultaneously or 2 h after morphine (Mor), at 1/20 the dose of Mor, inhibited the blockade of the proestrous gonadotropin release exerted by Mor, while the onset of the surges was delayed when it was given 3 h after Mor.

ISSN:0028-3835    

DOI:10.1159/000122868

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

In the female rabbit hypothalamus (HYP) the luteinizing hormone-releasing hormone (LHRH) and catecholamines (CAT) are mostly present in the granules and vesicles. A fraction of granules containing LHRH and vesicles containing CAT was obtained with 70% purity by ultracentrifugation in sucrose gradient. This fraction was devoid of synaptosomes.

ISSN:0028-3835    

DOI:10.1159/000122869

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Concentrations of luteinizing hormone (LH) and prolactin (Prl) in the serum of anestrous and cycling ewes were compared. The concentration of LH in serum and the frequency of episodic releases of LH were lower in anestrous than in cycling ewes. Concentrations of LH in serum rose as rapidly after ovariectomy of anestrous ewes as after ovariectomy of cycling ewes. Prl levels were higher during anestrus than at any stage of the estrous cycle; however, high Prl levels were not necessarily associated either with low LH levels or the absence of episodic release of LH. These data suggest: (1) that anestrus is not due to a reduction in the intrinsic ability of the hypothalamo-hypophyseal system to secrete LH, and (2) that high Prl levels may be a symptom rather than a cause of seasonal anestrus.

ISSN:0028-3835    

DOI:10.1159/000122870

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Secretory functions of the subcommissural organ (SCO) were investigated using mainly transmission and scanning electron microscopes, in 40 adult (19 males, 21 females) Trichosurus vulpecula which were caught in different seasons over several years. There is clear evidence of apical secretion, Reissner’s fiber (RF), a presumptive basal secretory material with associated perivascular space and labyrinthine basal lamina. Secretory function does not appear to be related to the sex of the animal or to the season when they were investigated. Radioimmunoassay of blood, SCO and pineal gland (PIN) for melatonin (MEL) was carried out in 18 adult animals in summer and winter. Gonads were also histologically examined. The SCO showed very little MEL. Findings suggest that the PIN of this animal has a low capacity to store and secrete MEL. Further, there is no evidence for the increased storage or secretion of MEL during darkness, and more specifically at midnight. The present investigators support the view that other indoles such as methoxytryptophol or pineal peptides may elicit the physiological effects of PI

ISSN:0028-3835    

DOI:10.1159/000122871

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The normal diurnal variation in plasma corticosterone (COR) was abolished and the response to ether stress was enhanced at 3 days following the production of medial forebrain bundle (MFB) lesions in male rats. However, by 7 days following surgery, basal plasma COR levels and the response to ether stress appeared normal. These alterations and subsequent recovery of pituitary-adrenal activity were accompanied by decreasing hypothalamic synaptosomal uptake of serotonin (5HT) and increasing synaptosomal uptake of dopamine (DA), evident at 3 and continuing at 7 days following the lesion. Uptake of norepinephrine (NE) was not affected at 3 days but showed a reduction at 7 days following surgery. The results suggest that disruption of ascending 5HT and NE fibers to the hypothalamus can alter pituitary-adrenal activity but that normal activity recovers by 7 days following the lesion. The correlation between recovery of pituitary-adrenal activity and increases in the normal uptake of hypothalamic DA suggest that DA may interact with 5HT and NE systems in the normal control of adrenocorticotrophin (ACTH) release.

ISSN:0028-3835    

DOI:10.1159/000122872

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The immunocytochemical approach was used to explore the possibility of local changes in immunoreactive gonadotropin releasing hormone (GnRH) of the median eminence (ME) during the estrous cycle in rats, and an attempt was made to correlate these changes with immunoreactive luteinizing hormone (LH) content in gonadotropic cells. On the day of proestrus, between 9:00 and 18:00 h, a severe depletion of GnRH from the medial palisade zone (MPZ) of the rostral part of the ME was observed whenever any marked changes in the density of GnRH present in the lateral palisade zone and in organum vasculosum of the lamina terminalis (OVLT) were visible. The depletion of GnRH from the MPZ was accompanied by a degranulation of LH-cells (stained with anti-pLH-β) in the pituitary which occurred over the same period. It is postulated that the MPZ of the rostral part of the ME contains the majority of nerve endings originating from the perikaya responsible for the cyclic surge of LH

ISSN:0028-3835    

DOI:10.1159/000122873

出版商:S. Karger AG    

年代:1979

数据来源: Karger