Ultrastructural autoradiographic localization of somatostatin-28 in the rat pituitary gland.

To identify the anterior pituitary cell type(s) containing somatostatin-28 (SS-28)-binding sites and to study the internalization processes of this peptide by the target cells, autoradiography was performed on rat anterior pituitaries removed at specific intervals (2-60 min) after iv injection of the [125I]iodo-SS-28 agonist [Leu8,D-Trp22,Tyr25]SS-28 into intact, adrenalectomized, or castrated male rats. At the light microscopic level, the silver grains were found in 75% of cells. Concomitant injection of an excess of unlabeled peptide prevented the binding of label, verifying the specificity of binding.

Localization and characterization of somatostatin-14 and somatostatin-28 receptors in the rat pituitary as studied by slide-mounted frozen sections.

The localization and characterization of somatostatin-14 (SS-14) and somatostatin-28 (SS-28) receptors were studied in the rat pituitary using the iodinated agonists [Tyr0, D-Trp8]-SS-14 and [Leu8, D-Trp22, Tyr25]-SS-28 as tracers. Slide-mounted frozen sections were used for the autoradiographic localization and biochemical characterization of somatostatin receptors. In the latter case, counting was performed on scraped off serial sections which contained both anterior and posterior pituitary.

[Intermediate lobe of the amphibian pituitary gland: an endocrine gland with multiple secretions and under multi-hormonal control].

The cells of the frog pars intermedia synthesize a 36 000 (36K) protein called proopiomelanocortin (POMC). After [3H]glucosamine incorporation, separation of newly synthesized products by SDS-polyacrylamide gel electrophoresis showed that this 36K protein was glycosylated. Tryptic mapping revealed only one site of glycosylation and showed that the carbohydrate side-chain was located in the N-terminal region of POMC.

[Role of alpha-MSH and related peptides in the central nervous system].

Alpha-melanocyte stimulating hormone (alpha-MSH) is a tridecapeptide secreted by intermediate lobe cells and synthesized in the brain as well. As a hormonal peptide, the physiological function of alpha-MSH consists mainly in the control of pigment movements within dermal melanophores. At the pituitary level, alpha-MSH secretion is under multifactorial control: it is inhibited by dopamine and GABA and stimulated by corticoliberin (CRF), thyroliberin (TRH), beta-adrenergic agonists and (or) serotonin.

Characterization and localization of vasoactive intestinal peptide receptors in the rat lung.

Experiments were performed to characterize vasoactive intestinal peptide (VIP) receptors in rat lung and to study their localization by means of light and electron microscope autoradiography. [125I]Iodo-VIP binding to lung homogenate was inhibited by synthetic VIP, [Val5]secretin, secretin, and 7-27 secretin with half-maximal inhibition (ID50) values of 1.62, 13, 121 nmol/liter and up to 0.

Radioautographic localization of somatostatin-14 and somatostatin-28 binding sites in the rat brain.

Somatostatin-14 (S14) and its precursor, somatostatin-28 (S28), are widely distributed throughout the rat brain, suggesting that they could act as neurotransmitter or neuromodulator in the central nervous system. The present study was undertaken to study the localization of S14 and S28 receptors in the rat brain determined by "in vitro" radioautography. The study performed on slide mounted frozen brain section with iodinated S14 and S28 analogs revealed an identical distribution of binding sites for the two forms of somatostatin.

[Intestinal ganglioneuromatosis: histochemical, histoenzymological and ultrastructural study of a case].

Report of a child with disseminated ganglioneuromatosis of the gut. The complexity of the intestinal nervous system malformation is proved by histochemical, histoenzymological and ultrastructural studies. The malformation is characterized by: hyperplasia and hypertrophy of enteric plexus and nerves bundles in the meso, high acetylcholinesterase activity, aplasia of the sympathetic innervation with the exception of perivascular plexus, qualitative and likely quantitative integrity of the endocrine digestive system.

Action of vasoactive intestinal peptide (VIP) on amphibian adrenocortical function, in vitro.

Vasoactive intestinal peptide (VIP) is located in chromaffin cells of the frog adrenal gland and is able to stimulate corticosteroid secretion in amphibians. In the present study we have investigated the possible involvement of prostaglandins, microfilaments and calcium in the mechanism of action of VIP on frog adrenocortical tissue. Rana ridibunda interrenal dice were perifused with amphibian culture medium for more than 10 hours.

Radioautographic study of binding and internalization of corticotropin-releasing factor by rat anterior pituitary corticotrophs.

In order to identify the anterior pituitary cell type(s) containing corticotropin-releasing factor (CRF) receptors and to study the internalization processes of this peptide by the target cells, radioautography was performed on rat anterior pituitaries removed at specific intervals (2-60 min) after intracarotid injection of [125I]iodo-CRF into intact and adrenalectomized female rats. In intact animals, all corticotrophs were labeled, whereas in the adrenalectomized animals about 80% of the hypertrophied corticotrophs (adrenalectomy cells) were. In control animals injected with both iodinated CRF and an excess of unlabeled peptide, no specific reaction could be detected.

[Chemodectoma of nerve X. Value and interest of the concept of the diffuse paraganglionic system].

Tenth nerve chemodectoma is one of the rarest varieties of cervicocephalic paragangliomas, far behind tumors developed from the carotid body. Based on findings in three patients, one reported previously, clinical and biological features of these formations are discussed. Recent data and those from personal studies are exposed, and arguments presented enabling the concept to be defended of a diffuse paraganglionic system in relation with the vagus nerve.

In vitro study of frog (Rana ridibunda Pallas) neurointermediate lobe secretion by use of a simplified perifusion system. III. Effect of neuropeptides on alpha-MSH secretion.

It has been previously demonstrated that thyrotropin-releasing hormone (TRH) stimulates in vitro the release of alpha-melanocyte-stimulating hormone (alpha-MSH) in frog. In the present study, the effects of various neuropeptides on spontaneous and/or TRH-induced alpha-MSH secretion were investigated, using a well-defined perifusion system technique. Vasoactive intestinal peptide, (VIP) a neurohormone which stimulates TRH target cells in mammals, was totally devoid of effect on frog melanotrophs although VIP-like material could be detected in neurointermediate lobe extracts.

Effect of Tyr-Pro-Leu-Gly-NH2 on melanotropin-stimulating hormone release in the frog and rat.

The tetrapeptide Tyr-Pro-Leu-Gly-NH2 (Tyr-MIFI) has been recently characterized in the hypothalamus and pineal of the rat. Since the concentration of Tyr-MIFI in the brain is increased by pinealectomy and is higher when the animals are in the dark, the possibility that Tyr-MIFI could be a physiological regulator of melanotropin secretion has been investigated. For this study a well-defined perifusion model has been applied, using whole neurointermediate lobes from male frogs (Rana ridibunda Pallas) or male Wistar rats.

In vitro study of frog (Rana ridibunda Pallas) neurointermediate lobe secretion by use of a simplified perifusion system. II. Lack of action of thyroxine on TRH-induced alpha-MSH secretion.

Thyrotropin-releasing hormone (TRH) stimulates alpha-melanocyte-stimulating hormone (alpha-MSH) secretion in amphibia as well as thyrotropin-stimulating hormone (TSH) and prolactin secretions in mammals. Since thyroid hormones regulate the stimulatory effect of TRH on TSH and prolactin, the possible role of thyroxine (T4) in the control of alpha-MSH secretion in amphibia, has been investigated. Neurointermediate lobes of Rana ridibunda were perifused in amphibian culture medium for 7 hr and the amounts of alpha-MSH released into the effluent perfusate were measured by radioimmunoassay.

Immunological characterization of endorphins, adrenocorticotropin, and melanotropins in frog hypothalamus.

To gain more information about the nature and regulation of opiomelanocorticotropic peptides in the frog diencephalon, radioimmunological determinations of alpha- and beta-MSH. ACTH, beta- and gamma-endorphins have been performed in hypothalamic extracts. Sephadex G-50 gel filtration revealed a single peak of alpha-MSH-like immunoreactivity (alpha-MSH-LI) comigrating with synthetic alpha-MSH.

Coexistence of vasoactive intestinal peptide and enkephalins in the adrenal chromaffin granules of the frog.

The chromaffin cells of the frog adrenal gland were studied at the electron microscopic level by means of the immunoperoxidase technique. Using specific antibodies against Met-enkephalin, Leu-enkephalin and vasoactive intestinal peptide (VIP), the coexistence of the three neuropeptides in the chromaffin cells was demonstrated. Furthermore, all three peptides were co-located in the 200-400 nm dense-core vesicles which also stained for dopamine-beta-hydroxylase.

Effect of ranitidine on healing of peptic ulcer: a 2-month study.

A multicenter trial of oral ranitidine 150 mg bid was conducted in 41 patients with duodenal and 30 with gastric ulcers. Patients were randomly allocated in double-blind fashion to 4 wk treatment with either ranitidine or placebo, after which all unhealed patients were given 4 wk on the active drug without breaking the original allocation code. After 4 wk of treatment the healing rate associated with ranitidine was significantly superior to that of placebo in both duodenal and gastric ulcer patients.

Co-localization of vasoactive intestinal peptide (VIP) and enkephalins in chromaffin cells of the adrenal gland of amphibia. Stimulation of corticosteroid production by VIP.

Recent studies have shown that biologically active peptides and monoaminergic neurotransmitters coexist in certain neuronal cell populations. Using the immunofluorescence technique, we have examined the localization of enkephalins, vasoactive intestinal peptide (VIP) and tyrosine hydroxylase in the adrenal gland of the frog Rana ridibunda. Most chromaffin cells which stained for tyrosine hydroxylase contained VIP-like immunoreactivity, whereas methionine- (Met-) and leucine- (Leu-) enkephalin-like immunoreactivity was detected in about 40% of the cells revealed by the anti-tyrosine hydroxylase serum.

Catecholaminergic control of alpha-melanocyte-stimulating hormone (alpha MSH) release by frog neurointermediate lobe in vitro: evidence for direct stimulation of alpha MSH release by thyrotropin-releasing hormone.

The role of dopaminergic and adrenergic innervation of the intermediate lobe of amphibian pituitary in the release of alpha MSH has been studied in vitro. Neurointermediate lobes of frog (Rana ridibunda Pallas) have been perifused in amphibian culture medium (ACM) for 5-7 h. alpha MSH released in the effluent perifusate was measured by means of a sensitive and specific RIA.

Effect of aldosterone antagonists on mineralocorticoid synthesis in vitro. Inhibition of aldosterone production by prorenoate-K.

A perifusion technique using frog adrenal glands has been applied to investigate the effects of long-term administration of a new aldosterone antagonist (potassium prorenoate; SC 23992) on mineralocorticoid production. Whatever the duration of administration of potassium prorenoate, at a constant concentration of 5 X 10(-4) M, a significant inhibition of aldosterone output occurred during the passage of the compound. The inhibition was immediate (lag period less than 10 min); the amplitude of the inhibition was constant during the whole experiment and ranged from 77 to 89%; the aldosterone output returned to a regular basal value 80-100 min after the end of infusion of potassium prorenoate.

Effect of hypophysectomy and pituitary stalk transection on alpha-melanocyte-stimulating hormone-like immunoreactivity in the brain of the frog, Rana ridibunda Pallas.

The existence of an alpha-MSH-like molecule in the frog brain led us to investigate the role of the pituitary gland in the maintenance of the alpha-MSH content in 3 different regions of the brain. Acetic acid extracts of hypothalamus, rhombencephalon and telencephalon were analyzed by means of a highly specific radioimmunoassay for alpha-MSH in normal, sham-operated, pituitary disconnected and hypophysectomized frogs. Transection of the pituitary stalk gave rise to a significant decrease in alpha-MSH content in the intermediate lobe of the pituitary gland (-71% after 3 days), but did not affect alpha-MSH content in the distal lobe or in the brain.