28 research outputs found
Estradiol-H3 Uptake by the Hypothalamus and the Lymbic Structures of the Androgenized Female Rats
Immunocytochemical characterization of afferents to estrogen receptor-containing neurons in the medial preoptic area of the rat
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Re-evaluation of 'frontal deafferentation' studies on the regulation of ACTH secretion in the light of CRF immunohistology
Frontal afferents to the medial basal hypothalamus of the rat were interrupted by a Halasz knife, and 4 weeks later the brains were processed for immunostaining of CRF-fibers. It was found that such intervention saves most of the CRF immunoreactive fibers of the paraventriculo-infundibular tract. Some of the conflicting results of earlier deafferentation studies are discussed on the basis of CRF immunohistology
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Effect of the isolated removal of the median eminence (ME) and pituitary stalk (PS) on the immunohistology and hormone release of the anterior pituitary gland grafted into the hypophysiotrophic area (HTA) and/or of the in situ pituitary gland
Isolated removal of the median eminence (ME) and pituitary stalk (PS) of female rats was performed under visual control, using a new instrument to open up the 3rd ventricle. Atrophy of the uterus, the follicles and the intersitial tissue in the ovaries was accompanied by persistent corpora lutea and persistent diestrous vaginal smears in rats which had undergone a successful removal of ME and PS. No change was, however, detected in the weight of the thyroid and adrenal glands at the end of the six weeks experimental period. An adenohypophysis implanted in the place of the ME at the time of the surgery, could not prevent these changes. In animals, in which the removal of the ME was not complete, the changes of the gonadal system were less pronounced. Immunocytology of the pituitary LH-, FSH, TSH- and prolactin-cells in animals with completely removed ME and PS showed inactive LH- and FSH-cells both in the grafted and in situ pituitaries, while the TSH- and prolactin-cells appeared to be in a stimulated state. In animals with ME remnant, LH-RH axon terminals were localized only on the blood vessels of the remnant. The part of the pituitary graft in contact with these blood vessels, as well as some areas of the in situ pituitary gland, contained active LH cells as judged from their size and immunohistological appearance. Since in the absence of the ME, the hypophysiotrophic area is not able to exert its regulatory effect on the gonadotrophs of the pituitary implant in this area, the authors suggest that this effect is mediated by the blood circulation of the ME which is rich in releasing hormones and is drained toward both the anterior pituitary and the medial basal hypothalamus
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LH-RH-containing neural elements in the rat hypothalamus
With the use of rabbit anti-LH-RH serum, a system of delicate nerve fibers and terminals which contain immunoreactive LH-RH can be demonstrated in the median eminence of the rat, corresponding exactly to the tubero-infundibular tract as described earlier with the aid of classical neurophistological methods. The delicate fiber system can be traced to the region of the rectrochiasmatic area and especially to that of the arcuate nucleus but not farther. Nerve cells do not show any immunopositive reaction for LH-RH in the experimental conditions studied. LH-RH positive nerve fibers terminate on or in the immediate vicinity of the capillary loops penetrating the median eminence
Ultrastructural analysis of estrogen receptor immunoreactive neurons in the medial preoptic area of the female rat brain
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Ontogenesis of the LH-RH-containing neuronal elements in the hypothalamus of the rat
LH-RH-containing neuronal elements were detected earliest in the median eminence and in the vascular organ of the lamina terminalis of newborn rats. The peroxidase-labeled antibody method was used. Since the synthesis of the gonadotrophic hormones starts already on the 18th day of intrauterine life in the rat, this finding does not support the view that LH-RH could have inductive effect on the differentiation of the gonadotropic cells of the anterior pituitary gland
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Localization of LH-RH-containing Neurons in the Rabbit Brain
In the last three years immunohistologic methods have successfully been used to localize the hypophysiotrophic (releasing and inhibiting) hormones. The first releasing hormone localized by immunohistologic methods in the guinea pig by LEONARDELLI et al. in 1973 was luteinizing hormone-releasing hormone (LH-RH). The species studied so far for the histologic localization of LH-RH include guinea pig, rat, mouse, duck, toad, cat, dog, and greenfinch (BARRY and CARETTE, 1975; SÉTALÓ, 1976)