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Biomedical subjects

M Sar

Publications and source records attributed to M Sar.

At least 145 records · Page 8Linked to original sources
PubMed1979

Relationships between the catecholaminergic and enkephalinergic systems demonstrated by a combined technique of formaldehyde-induced fluorescence and immunocytochemistry.

A technique for the localization of catecholamines and enkephalin in the same tissue section is described. Sections from rat brains prepared according to the Falck-Hillarp technique were examined by dark field fluorescence microscopy and then processed for immunocytochemistry for leucine-enkephalin (leu-enk) using the unlabeled antibody technique. In the medial hypothalamus the distribution of the catecholamines and enkephalin is complementary, while in the lateral hypothalamus the patterns are similar but not identical. Enkephalin terminals are also observed in and around the locus coeruleus, while enkephalin cell bodies are adjacent to the nucleus.

Animals↗
PubMed1978

Topography of estrogen target cells in the forebrain of goldfish, Carassius auratus.

The topographical distribution of estradiol-concentrating cells in the brain of male and female teleost, Carassius auratus, was determined by autoradiography, after injection of 3H estradiol-17beta. Radioactively labeled neurons are found in specific regions of the forebrain, with a similar topographical distribution both in males and females. Regions of accumulation of estrogen target cells include the supracommissural area of the telencephalon, the preoptic area, the central hypothalamic area and the thalamic area. Unlabeled estradiol injected prior to the administration of 3H estradiol reduces or eliminates nuclear uptake of radioactivity. The autoradiographic results demonstrate the existence of estrogen target neurons in the teleost forebrain at sites similar to those described in mammalian brains. However, under the conditions of the experiment, there exists no pallial representation of estrogen target cells.

Animals↗
PubMed1978

Immunohistochemical localization of enkephalin in rat brain and spinal cord.

The distribution of immunoreactive enkephalin in rat brain and spinal cord was studied by immunoperoxidase staining using antiserum to leucine-enkephalin ([Leu5]-enkephalin) or methionine-enkephalin ([Met5]-enkephalin). Immunoreactive staining for both enkephalins was similarly observed in nerve fibers, terminals and cell bodies in many regions of the central nervous system. Staining of perikarya was detected in hypophysectomized rats or colchicine pretreated rats. The regions of localization for enkephalin fibers and terminals include in the forebrain: lateral septum, central nucleus of the amygdala, area CA2 of the hippocampus, certain regions of the cortex, corpus striatum, bed nucleus of the stria terminalis, hypothalamus including median eminence, thalamus and subthalamus; in the midbrain: nucleus interpeduncularis, periaqueductal gray and reticular formation; in the hind brain: nucleus parabrachialis, locus ceruleus, nuclei raphes, nucleus cochlearis, nucleus tractus solitarii, nucleus spinalis nervi trigemini, motor nuclei of certain cranial nerves, nucleus commissuralis and formatio reticularis; and in the spinal cord the substantia gelatinosa. In contrast enkephalin cell bodies appear sparsely distributed in the telencephalon, diencephalon, mesencephalon and rhombencephalon. The results of the histochemical staining show that certain structures which positively stain for enkephalin closely correspond to the distribution of opiate receptors in the brain and thus support the concept that the endogenous opiate peptides are involved in the perception of pain and analgesia. The localization of enkephalin in the preoptic-hypothalamic region together with the presence of enkephalin perikarya in the paraventricular and supraoptic nuclei suggest a role of enkephalin in the regulation of neuroendocrine functions.

Animals↗
PubMed1978

Estrogen target sites in the cloacal region of female and male chick embryos.

After intravenous injection of 3H-estradiol in the 12-day old chick embryo, radioactivity is concentrated in nuclei of certain cells in the cloacal area. The nuclear labeling is observed in mesenchymal cells along the different portions of the cloaca, and in an unidentified tissue located laterally to the cloaca. The labeled mesenchymal cells display a definite pattern of distribution along the epithelial wall of the cloaca, identical both in male and in female embryos. In the adjacent bursa of Fabricius, cells do not concentrate labeled hormone in their nuclei. The presence of estrogen receptors in the cloacal area of embryos of either sex adds evidence, at the cellular level, to support the concept of a "neutral", or undifferentiated, sex with estradiol inhibiting this "neutral" male differentiation.

Animals↗
PubMed1978

Bipotentiality of response to sex hormones by the prostate of castrated or hypophysectomized dogs. Direct effects of estrogen.

Prostatic response to administered estradiol-17beta 17-cyclopentylpropionate (ECP) was studied in castrated or hypophysectomized dogs. Ultrastructural investigation identified two types of epithelial cells, squamous and modified glandular, that resulted from estrogen action. Squamous cells, which predominated, appeared to evolve from basal reserve cells. Estrogen-modified glandular cells have features attributable to estrogen and previous androgen stimulation. Thaw-mount autoradiography of explants located radiolabeled estrogen in prostatic epithelium and stroma of normal and ECP-treated animals, suggesting a role of estrogen in prostatic homeostasis. Epithelium from ECP-treated dogs incorporated 3H-thymidine, indicating that estrogen promotes DNA synthesis in these cells. Greatly enhanced conversion of radiotestosterone to 4-androstene-3,17-dione, with sharply decreased formation of 5alpha-reduced hydroxylation products, and attendant elevation in estradiol-17beta oxidoreductase activity are metabolic markers attributable to the induced squamous and responding stromal cells. The duality of prostatic response to sex hormones is apparent from observations that estrogen stimulates regressed glandular epithelium which had undergone androgen-mediated differentiation before ablation.

Animals↗
PubMed1977

The collicular recess organ: evidence for structural and secretory specialization of the ventricular lining in the collicular recess.

The collicular recess organ and adjacent portions of the collicular recess were studied by light microscopy, scanning electron microscopy and transmission electron microscopy. In the collicular recess, the ventricular wall contains folds and is well vascularized. The adluminal ependymal cells generally bear kinocilia and microvilli on their ventricular surface. Among the cilia, many secretory droplets, some axons, and few supraependymal cells are seen. Various stages of apocrine ependymosecretion are observed. In addition to tanycytes, coelocytes are found scattered throughout the ependymal lining of the collicular recess. Coelocytes, characterized by lumina containing cilia and a few microvilli, are accumulated in ependymal and hypependymal positions of the collicular recess organ at the roof of the collicular recess.

Animals↗
PubMed1977

Autoradiographic studies of 3H-dexamethasone uptake by immunocytochemically characterized cells of the rat pituitary.

3H-Dexamethasone (10 microgram/kg) was injected intravenously in adrenalectomized rats and after survival times of 5, 30, 60, and 180 min its uptake within the pituitary was studied by autoradiography. Radioactivity was concentrated in cell nuclei in the pars nervosa and pars distalis. Within the pars intermedia, only cells of the marginal zone were labeled. In the pars distalis, some cells showed a weak nuclear accumulation of radioactivity as early as 5 min after injection. The tissue radioactivity was nearly maximal at 5 min, and the proportion of radioactivity in nuclei reached a maximum of 60-70% by 30 min. In competition experiments, non-radioactive steroids (1 mg/kg) were injected 5 min before 3H-dexamethasone and sacrifice was 30 min later. Dexamethasone markedly diminished the nuclear accumulation in the pars distalis, but corticosterone and progesterone did not. In the pars nervosa, corticosterone and progesterone competed for nuclear uptake of 3H-dexamethasone, although less effectively than dexamethasone itself. Different cell types in the pars distalis were characterized by treating autoradiograms with an immuno-peroxidase bridge procedure. Cells treated with anti-ACTH 17-39 had the greatest nuclear concentration of radioactivity, and those stained with anti-TSH were least heavily labeled. Cells treated with antisera to GH, PRL, and hCG were moderately labeled.

Adrenalectomy↗
PubMed1977

Androgen concentration in motor neurons of cranial nerves and spinal cord.

After injection of [3H]dihydrotestosterone, a major testosterone metabolite, radioactivity is concentrated in nuclei of certain cells in the midbrain, pons, medulla oblongata, cerebellum, and spinal cord. While there is some overlap between androgen and estrogen target neuron distribution, certain motor neurons appear to be selectively labeled by androgen; in contrast, estrogen localization prevails in sensory neurons. These results may help to explain why male sexual behavior in some rodents is not fully activated with dihydrotestosterone alone but in addition requires estradiol, a testosterone metabolite.

Adrenalectomy↗
PubMed1977

The heart: a target organ for estradiol.

Autoradiographic studies of rat heart reveal that tritiated estradiol concentrates in cell nuclei of the myocardium of the atria and auricles, similar to the myometrium of the uterus. This suggests that estrogen has a direct effect on atrial myocytes through which its "protective" action may be mediated. Cardiac glycosides that are known to exert estrogen-like effects on classical estrogen target tissues, such as uterine muscle, endometrium, vagina, and mammary gland, probably act on atrial muscle through a genomic, steroid hormone-like mechanism of action.

Animals↗
PubMed1977

Steroid hormone target cells in the periventricular brain: relationship to peptide hormone producing cells.

Steroid hormone concentrating cells in hypothalamic and extrahypothalamic regions are reviewed and the topographic relationship to the periventricular brain and the ventricular recess organs is discussed. Steroid hormone target cells in the brain are considered feedback sites and production sites of polypeptide hormones. The anatomical distribution of estrogen, androgen and progestin target neurons, as defined by autoradiography, is compared with the localization of antibodies to luteinizing hormone-releasing hormone and somatostatin in perikarya of neurons, as characterized by immunocytochemistry. Around the optic recess of the third ventricle in the lamina terminalis and the preoptic nucleus as well as in the periventricular nucleus of the hypothalamus, the steroid hormone target neurons and the assumed polypeptide hormone producing neurons occupy corresponding sites.

Amygdala↗
PubMed1976

Anatomical distribution of estrogen target cells in the avian CNS: a comparison with the mammalian CNS.

The distribution of labeled cells was investigated in the brain of the ring dove one hour after administration of 3H-estradiol. Major areas of concentration of labeled cells were found in (1) the preoptico-strial region: nucleus preopticus medialis and nucleus interstitialis of the dorsal olfactory projection, (2) the basal hypothalamic region: nucleus hypothalamicus posterior medialis and nucleus inferior, (3) the amygdaloid region: nucleus taeniae and adjacent portions of the archistriatum, and (4) the midbrain: substantia grisea surrounding the nucleus mesencephalicus lateralis, pars dorsalis. The findings support the phylogenetic homologies between the avian nucleus interstitialis of the dorsal olfactory projection and the mammalian nucleus interstitialis of the stria terminalis, the avian nucleus hypothalamicus posterior medialis and the mammalian nucleus ventromedialis hypothalami, as well as the avian nucleus inferior and the mammalian nucleus infundibularis-premammillaris ventralis. The results also suggest that the nucleus medialis and other more differentiated labeled areas of the mammalian amygdala.

Animals↗
PubMed1976

Regional differences between nuclear concentration of (3H) estradiol and (3H) progesterone and their action on the uterus of rat during delayed implantation.

The cellular and subcellular localization of radioactivity by dry-mount autoradiography was studied at 5, 15 and 30 minutes after intraluminal or at 5, 15, and 60 minutes after subcutaneous administration of (3H) estradiol or (3H) progesterone to rats in which implantation was delayed by ovariectomy on day 3 post-coitum, followed by treatment with progesterone. After intraluminal instillation of (3H) estradiol or (3H) progesterone, radioactivity was cleared from the uterine lumen at 5 minutes. After intraluminal as well as subcutaneous injection of (3H) estradiol, radioactivity was concentrated at all time intervals in the nuclei of cells of the substantia propria, glands and muscularis, but not in the luminal epithelium. White blood cells and endothelial cells were unlabeled, while perivascular cells showed concentration of radioactivity. After intraluminal instillation of (3H) progesterone, radioactivity was retained in the cytoplasm of the luminal epithelium at 5 and 15 minutes, while no such concentration appeared after subcutaneous injection. No selective nuclear retention was observed in the luminal epithelium, in contrast to the substantia propria and muscularis. The autoradiographic results indicate that progesterone treatment simulating the conditions of early pregnancy, changes the uptake affinity of uterine tissues for (3H) estradiol. The lack of a detectable concentration of estrogen within nuclei of the luminal epithelium does not preclude hormone action. Possible mechanisms of metabolic activation of the uterine luminal epithelium in the apparent absence of concentration of (3H) estradiol to nuclei of the luminal epithelium are discussed.

Animals↗