Biomedical subjects
Publications and source records attributed to M Sar.
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Estrogen-concentrating cells in the brain of river lamprey, Ichthyomyzon unicuspis, are identified and mapped by thaw-mount autoradiography. After injection of 3H-estradiol-17 beta, cells with nuclear concentration of radioactivity are found in the ventral periventricular area of the telencephalon, and in preoptic, central hypothalamic, and thalamic regions of the diencephalon, while in the pallium no such target cells are found. Injection of unlabeled estradiol prior to the administration of 3H-estradiol reduces of eliminates the nuclear concentration of radioactivity. The autoradiographic results demonstrate the presence of estrogen target cells in the brain of descendents of one of the phylogenetically earliest vertebrate lines. The topographical distribution of these target neurons, which are accumulated in certain periventricular structures, is similar to the distribution of estrogen target neurons described previously for other nonmammalian and mammalian vertebrates. Accordingly, estrogen feedback and activation sites are present throughout vertebrate phylogeny.
Sex steroid hormones and catecholamines have physiological interactions in the brain. By the combined use of autoradiography and fluorescence histochemistry, steroid hormone target sites and catecholamine neurons were visualized simultaneously in the same tissue preparation. By this dual localization method, [3H]estradiol and [3H]dihydrotestosterone target sites were identified in nuclei of many catecholamine cell bodies in the brainstem, and catecholamine nerve terminals were observed near certain steroid hormone target neurons. These results suggest close anatomical interrelations between steroid hormone sites of action and catecholamine sites of production and action in the brain.
In the anterior pituitary of the rat, target cells of 1,25 (OH)2 vitamin D3 are identified as those that secrete thyroid stimulating hormone by means of a combined technique of thaw-mount autoradiography and immunohistochemistry. The results for the first time provide evidence that suggests a central effect of 1,25 (OH)2 vitamin D3 on the modulation of thyrotropin secretion in a manner similar to that of other steroid hormones at the level of the pituitary.
Mature rats raised on a vitamin D deficient diet were injected with tritium labeled, 1,25 dihydroxyvitamin D3. Concentration of radioactivity, which is prevented by pretreatment with unlabeled 1,25 dihydroxyvitamin D3, is found in nuclei of cells that are centrally located in pancreatic islets. The central location of these cells and supportive evidence from the literature suggest that they are B-cells, and that 1,25 dihydroxyvitamin D3 has a direct and genomic action on B-cell functions including insulin secretion.
Swiss albino mice were injected on day 16 of pregnancy with 3H diethylstilbestrol. Fetuses were sacrificed 3 h afterwards, frozen, and processed for thaw-mount autoradiography. The serial sections from 4 fetuses were studied. Intense nuclear concentration of radioactivity was found in the mesenchymal cells directly surrounding the epithelial primordia of the mammary glands, but not in the epithelium itself. Localization was similar in male and female fetuses. These findings are discussed in relation to their developmental, teratological, and onocological implications.
Immunocharacteristics of the pars distalis cells of the pituitary of the male lizard A. carolinensis are determined by employing the immunoperoxidase technique with antisera to mammalian pituitary hormones. On the basis of their immunoreactivity, 5 different cell types with characteristic anatomical distribution are recognized. ACTH cells are found in the rostral half of the pars distalis, and PRL cells in the rostral two thirds of the pars distalis. GH and TSH cells are located in the caudal half of the pars distalis. GTH cells are distributed throughout the gland. When consecutive sections are stained with antiserum to ovine FSH or its beta-subunit and to ovine LH, the same cells show immunoreactivity to all the three antisera. None of the GTH cells show positive immunoreactivity to ovine beta-LH antiserum. The results suggest the existence of one gonadotropic cell type in the pituitary of this lizard.
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A combined technique of dry-mount autoradiography and immunoperoxidase staining is described for the localization of steroid hormones and neuropeptides in the same brain section. With this procedure [3H]estradiol is localized in nuclei of neurophysin and arginine vasopressin producing cells of the mouse supraoptic and paraventricular nucleus. The results suggest a direct action of estradiol on neurohypophysial hormone producing cells. This immunoautoradiographic technique is suitable for the simultaneous localization of steroid hormones and neuropeptides in the brain.
Results of thaw-mount autoradiographic studies of kidney obtained 1--3 hr after a single injection of 1,25-(OH)2-[3H]vitamin D3 to rats showed strong nuclear concentration of radioactivity in podocytes and cells of distal tubules, including the pars convoluta, macula densa, and pars recta. Intermediate nuclear concentration was found in cells of the thin limb of Henle's loops, whereas weak or no nuclear uptake was seen in cells of the proximal tubules. In contrast, after injection of 3H-labeled parathyroid hormone or [3H]estradiol, mainly cells of the proximal tubules were labeled; after 3H-labeled parathyroid hormone, apical cytoplasmic uptake of radioactivity was seen most strongly in the proximal part of the proximal tubules, whereas, after [3H]estradiol, weak nuclear concentration was seen in cells throughout the proximal tubules. The results are consistent with the concept that synthesis of 1,25-(OH)2-vitamin D3 occurs in the proximal tubules under stimulation of parathyroid hormone or estradiol (or other hormones) and that the major site of action of 1,25-(OH)2-vitamin D3 is in the distal tubules.
Serial sections from 16-day mouse embryos from mothers injected with 3H-diethylstilbestrol were processed for autoradiography. The distribution, in the laryngeal region, of cells with nuclear concentrations of radioactivity was analyzed. Estrogen receptor cells were found in the mesenchyme of the vocal cords and lateral to the laryngeal aditus. The embryological and oncological implications of these findings are discussed.
The distribution of oestrogen and androgen target cells in the anterior pituitary gland of the chick embryo on days 10, 12 and 15 of incubation was studied 1 h after the injection of tritium-labelled steroid hormone using the thaw-mount autoradiographic technique. Oestradiol target cells were localized in the caudal zone that corresponds to the so-called 'caudal lobe', while androgen target cells were found throughout the rostral and caudal lobes of the anterior pituitary gland. With a combined autoradiography and immunohistochemistry technique, most of the oestrogen target cells showed immunoreactivity to turkey LH antiserum but not to adrenocorticotrophin (1-24) and beta-thyrotrophin antisera. In contrast, androgen target cells did not show positive immunoreactivity to the three antisera used. The results suggested a direct and early involvement of oestrogens but not of androgens in the feedback regulation of pituitary gonadotrophin secretion in the chick embryo.
After mature rats that had been fed on a vitamin D3-deficient diet were injected with tritium-labeled 1,25-dihydroxyvitamin D3, radioactivity became concentrated in nuclei of luminal and cryptal epithelium of the duodenum, jejunum, ileum, and colon; in nuclei of the epithelium of kidney distal tubules including the macula densa, and in podocytes of glomeruli; in nuclei of the epidermis including outer hairshafts and sebaceous glands; and in nuclei of certain cells of the stomach, anterior and posterior pituitary, and parathyroid. These results reveal cell types that contain receptors for 1,25-dihydroxyvitamin D3 or metabolites of this compound both in known or hypothesized target tissues and in tissues that were previously unknown to participate in vitamin D3 metabolism.
Autoradiographic studies with 3H aldosterone demonstrate nuclear concentration of hormone in neurons of the hippocampus, septum, allocortical regions and brain stem reticular formation and motor nuclei of cranial nerves and in the meninges. The results suggest that mineralocorticoids have wide ranging effects on different parts of the central nervous system.
In the platyfish, Xiphophorus maculatus, after injection of [3H]estradiol-17 beta, nuclear concentration of radioactivity is observed in certain cells of the forebrain. These labeled cells are accumulated in periventricular midline regions that include in the telencephalon the ventral precommissural and dorsal supracommissural areas, and in the diencephalon the preoptic, central hypothalamic and thalamic areas. The specialized ependyma of the subcommissural organ also shows nuclear concentration of radioactivity, while other ependymal cells remain unlabeled. Similar to other vertebrate classes, the accumulations of estrogen target cells exist characteristically in the vicinity of the ventricular system, especially its recesses. This implies close topographical relationships between estrogen target cells and the ventricular recess organs, including the optic recess organ, the infundibular recess organ, the paraventricular organ and the subcommissural organ. Different from other vertebrate classes, no pallial accumulations of estrogen target cells are seen in the teleost.
The distribution of estradiol-concentrating cells in the pituitary of the platyfish, Xiphophorus maculatus, is studied after the injection of 3H estradiol-17 beta by thaw-mount autoradiography. Autoradiograms prepared 2-8 h after the injection show nuclear concentration of radioactivity in certain cells of the rostral pars distalis, pars intermedia and pars nervosa. Radioactively labeled cells are identified as gonadotropes by a combined technique of thaw-mount autoradiography and immunoperoxidase staining with antiserum to ovine LH. Approximately 80% of the immunoreactive LH cells show a concentration of radioactivity in their nuclei. These observations indicate that in teleosts, as in mammals, estradiol has a direct effect on pituitary gonadotropes.
The immunocharacteristics of androgen target cells in the anterior pituitary of male rats are assessed by a combined thaw-mount autoradiography and immunoperoxidase staining method permitting the simultaneous identification of steroid-hormone target cells and protein or polypeptide hormone-producing cells in the same preparation. After injection of 3H-dihydrotestosterone, nuclear concentration of radioactivity is observed in cells of the anterior lobe, in "ectopic" cells in the intermediate and posterior lobes as well as in certain pituicytes. The radioactively labeled cells in the anterior lobe are identified immuno-histochemically as gonadotropes and thyrotropes with the use of antiserum to ovine LH or its subunit beta-LH and bovine beta-TSH. The results suggest genomic effects of androgen on gonadotropes and thyrotropes as well as pituicytes.