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Biomedical subjects

G Pelletier

Publications and source records attributed to G Pelletier.

At least 649 records · Page 36Linked to original sources
PubMed1976

Electron microscope immunohistochemical localization of neurophysin in the rat with hereditary diabetes insipidus.

In order to study the subcellular distribution of neurophysin in the rat with hypothalamic hereditary diabetes insipidus (DI), an immunoelectron microscopic localization of neurophysin was performed in the hypothalamo-neurohypophysial system of both homozygous and heterozygous DI rats. Whereas in control rats neurophysin was localized in the granules present in the secretory neurons, in the homozygous DI rats neurophysin was found in the granules and outside the granules in the perikarya and axons of neurons of both supraoptic and paraventricular nuclei. In the heterozygous DI rats findings similar to those observed in homozygous DI rats were observed, although in the posterior pituitary, the exgranular material appeared to be less abundant than in homozygous DI rats. These results clearly demonstrated that in hyperstimulated neurons neurophysin was distributed in both granular and extragranular compartments.

Animals↗
PubMed1976

Electron microscopic immunohistochemical localization of vasopressin and neurophysin in the median eminence of normal and adrenalectomized rats.

Using an immunoperoxidase technique at the ultrastructural level, vasopressin (VP) and neurophysin (NP) were localized in the axons of the median eminence of normal and adrenalectomized rats. Whereas VP and NP were generally found in 150-nm granules in the internal zone of the normal rat median eminence, in the adrenalectomized rat, many granules of about 80 to 100 nm in diameter were found to contain NP and VP in the external zone of the median eminence.

Adrenalectomy↗
PubMed1976

Identification of gonadotropic cells in the human pituitary by immunoperoxidase technique.

Using specific antibodies against the beta-subunits of human LH and FSH, the pituitary cells which produce the two gonadotropins have been localized in the human pituitary by an immunoperoxidase technique. In serial semi-thin sections (2 mum), it was clearly shown that about 90% of gonadotropic cells contained both FSH and LH, whereas the remaining 10% of gonadotrophs were positive only for FSH. At the ultrastructural level, the gonadotrophs containing both LH and FSH were characterized by the presen-e of two types of secretory granules: the smaller ones which whowed a strong immunohistochemical reaction and the larger ones which generally presented a weaker reaction.

Antibodies↗
PubMed1976

Immunohistochemical localization of somatostatin in endocrine cells of the rat stomach.

Using an immunohistochemical technique involving unlabeled antibody and the peroxidase-anti-peroxidase complex, we have localized somatostatin (or growth hormone-release inhibiting hormone), a hypothalamic hormone which can also inhibit gastrin secretion, in the rat stomach. Somatostatin was found to be present in a few cells in the mucosa of the pyloric antrum. These cells are characterized by the presence of secretory granules of about 150-250 nm in diameter and are probably endocrine cells.

Animals↗
PubMed1976

Study of the natural antihistamine-like substance in bile in mammals.

A natural antihistamine substance (NAS) present in bile has been investigated. It was found that the antihistamine activity was not due to proteins, lipids, pigments, or amino acids. On ion exchange chromatography and thin-layer chromatography, this activity was associated with bile acids. Many bile acids could, in varying degrees, inhibit this histamine induced guinea pig ileum contraction, desoxycholic acid being the most potent. However NAS activity could be separated from bile acids and their conjugates using a different solvent system. Furthermore, NAS showed a higher antihistamine activity than bile acids. This substance seems to be responsible for 15-20% of the activity of whole bile. The substance has not yet been identified.

Animals↗
PubMed1976

Immunohistochemical localization of hypothalamic hormones.

Using an immunoperoxidase technique at the light and electron microscope levels, the localization of somatostatin and luteinizing hormone-releasing hormone (LH-RH) has been performed in the brain, as well as the pancreas and stomach. The following generalizations may be drawn on the localization of LH-RH and somatostatin. (a) LH-RH and somatostatin are contained in axons and nerve endings of the median eminence and organum vasculosum of the lamina terminalis. (b) LH-RH and somatostatin are present in different nerve endings. (c) In the subcommissural organ, subfornical organ and area postrema, the two neurohormones are present in the cytoplasm of ependyman and subependymal cells. (d) In the endocrine pancreas and gastric mucosa, somatostatin is localized within the secretory granules of specific endocrine cells.

Adrenalectomy↗
PubMed1976

Electron microscope immunohistochemical localization of thyroglobulin in the rat thyroid gland.

In order to make a precise identification of the organelles containing thyroglobulin (TG) in the thyroid follicular cells, an electron microscope immunohistochemical localization of TG was conducted in the rat thyroid gland. In both control and TSH-treated rats, TG was detected in the follicular lumen, in large vesicles which correspond to the classical colloid droplets, in apical vesicles, and also in the apical cytoplasm. When the formation of colloid droplets was prevented by the previous administration of L-thyroxine, a positive reaction for TG was observed only in the colloid and apical vesicles, and diffusely in the cytoplasm. These results clearly establish for the first time the presence of immunoreactive TG in apical vesicles, luminal colloid and colloid droplets, and cytoplasm (possibly cell sap). They confirm previous indirect evidence suggesting that apical vesicles are involved in the transport of TG and that colloid droplets whose formation is induced by TSH, do contain TG.

Animals↗
PubMed1975

[Karyotype of Nicotiana tabacum L. artificial haploids].

Twenty-five platelets obtained by culturing anthers of Nicotiana tabacum L. var. "Wisconsin 38" are haploids (22) or mixoploids (3). Numerous aneuhaploid cells were observed in 15 haploid plants (n = 18, 20, 22, 23, 25, 26, 28). Such a chromosomic variability careful caryological studies of haploid plants before these are used in genetic work.

Haploidy↗
PubMed1975

Immunohistochemical detection of growth hormone-release inhibiting hormone (somatostatin) in the guinea-pig brain.

Utilizing the unlabeled antibody peroxidase-antiperoxidase method, we have studied the distribution of somatostatin (growth hormone release-inhibiting hormone) in the guinea pig brain. An immunohistochemical reaction was found in both internal and external zone of the caudal and median portions of the median eminence. Reaction products were also present in the arcuate nucleus in proximity of the third ventricule. The immunostained elements resembled nerve processes. No cell bodies were stained. A positive reaction was also present in the whole organum vasculosum of the lamina terminalis. In the subfornical and subcommissural organs, somatostatin was observed in the ependymal and subependymal layers and the perivascular areas. In the pineal gland, a positive reaction was also found mainly in the perivascular areas. All the other brain areas were completely negative. These results establish that, in the hypothalamus, somatostatin is mainly concentrated in the median eminence and suggest that periventricular organs can play a role in the regulation of growth hormone secretion.

Animals↗
PubMed1975

Ultrastructural study of the uptake of peroxidase by the rat median eminence.

An active role of the ependymal cells (tanycytes) of the median eminence in the transport of hypothalamic hormones has been recently suggested. In order to investigate the fate of material present in the cerebrospinal fluid, a protein tracer, horse-radish peroxidase (HRP) was injected into the left lateral ventricle of rats. Two minutes after the injection, HRP had largely diffused between tanycytes and hypendymal cells. As soon as 5 min after the injection, HRP had completely penetrated all the layers of the median eminence. A few labelled vesicles and lysosomes were occasionally seen in ependymal and glial cells. At longer time intervals (20 min, 1 and 4 hrs), a reaction was observed in the lumen of fenestrated capillaries of the pituitary portal plexus. In many nerve endings of the external zone, vesicles and lysosomes were seen to contain HRP. An interesting observation was the localization of HRP between nerve endings and cells in both the pars nervosa and the pars intermedia of the pituitary gland. No reaction was recorded in the anterior pituitary and the kidney. Seventeen hours after the injection, the extracellular space was free of reaction but a few positive intracellular structure were still found. These results clearly indicate that some material from the third ventricle can rapidly diffuse between cells and axons of the median eminence to reach the fenestrated capillaries of the pituitary portal plexus and the posterior pituitary without involving an active transport by tanycytes.

Animals↗
PubMed1975

Distribution of radioactivity in the organs of the rat and mouse after injection of (125I)alpha-melanocyte-stimulating hormone.

The distribution of radioactivity after intrajugular injection of 125I-labelled alpha-melanocyte-stimulating hormone (alpha-MSH) was studied by whole-body autoradiography of the mouse and by direct measurement of radioactivity in individual organs of the rat. Very high uptake of radioactivity in the pineal gland was measured 5 min after the injection of (125I)alpha-MSH. Lower levels of accumulation of radioactivity were found in the kidney and in the posterior (including intermediate) lobe of the pituitary. High uptake was also found in the thyroid, stomach, and oesophagus. The specificity of uptake of (125I)alpha-MSH into the pineal and pituitary is suggested by the very low uptake of Na125I into those tissues.

Adrenal Glands↗
PubMed1975

Distribution of radioactivity in the organs of the rat and mouse after injection of L-(3H)prolyl-L-leucyl-glycinamide.

The distribution of radioactivity after intrajugular injection of L-(3H)-prolyl-L-leucyl-glycinamide has been studied by whole-body autoradiography in the mouse and by direct measurement of radioactivity in individual organs of the rat. There is good agreement between results obtained with the two techniques and animal species. High levels of radioactivity were found in the pineal gland, anterior pituitary, posterior (including intermediate) lobe of the pituitary, and epididymal and brown fat. Lower uptake of radioactivity occurred in the submaxillary gland, kidney, and adrenal gland. The preferential uptake of radioactivity by the pineal gland after injection of the labelled tripeptide suggests a role for this hypothalamic hormone in the control of pineal activity.

Adipose Tissue↗