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M Villar

Publications and source records attributed to M Villar.

At least 37 records · Page 2Linked to original sources
PubMed1993

Nitric oxide synthase in the rat anterior pituitary gland and the role of nitric oxide in regulation of luteinizing hormone secretion.

By using immunohistochemistry and in situ hybridization, we have demonstrated that the nitric oxide (NO)-synthesizing enzyme NO synthase is present in gonadotrophs and in folliculo-stellate cells of the anterior pituitary gland of male and female rats. A marked increase in levels of NO synthase protein and mRNA was observed after gonadectomy. In vitro studies on dispersed anterior pituitary cells suggest that NO inhibits gonadotropin-releasing-hormone-stimulated luteinizing hormone release. An inhibitory effect of NO has also been shown on growth-hormone-releasing-hormone-stimulated release of growth hormone [Kato, M. (1992) Endocrinology 131, 2133-2138]. Thus these findings support a dual mechanism for NO in the control of anterior pituitary hormone secretion, an autocrine mediation of luteinizing hormone release on gonadotrophs, and a paracrine effect on growth hormone secretion involving folliculo-stellate cells closely related to somatotrophs. We speculate that NO may participate in producing the pulsatile secretion patterns of these two pituitary hormones.

Amino Acid Oxidoreductases↗
PubMed1992

Evidence for upregulation of galanin synthesis in rat glial cells in vivo after colchicine treatment.

The localization of galanin (GAL) and GAL mRNA was studied in rat brain after colchicine or vinblastine treatment using in situ hybridization and immunohistochemistry. GAL-like immunoreactivity was found in glial cells, presumably activated microglia, in the cortex, caudate nucleus and septum, mainly on the injection side. GAL mRNA expression was found in small cells in the same areas with an overlapping distribution, including the adjacent white matter. The results suggest that the glial cells initiate synthesis of the peptide GAL in response to intraventricular injection of high doses of the 2 mitosis inhibitors.

Animals↗
PubMed1992

[Spontaneous pneumothorax and Pneumocystis carinii pneumonia. Something more than a casual association?].

The association of spontaneous pneumothorax and Pneumocystis pneumonia is not frequent. The medical literature reports a ratio between 0 and 5.7%. In 18 patients admitted in our hospital, in the last two years, and diagnosed of AIDS and Pneumocystis pneumonia, we observed two cases of pneumothorax spontaneous. They represent the 11%. In one of them spontaneous pneumothorax was the first manifestation and in the other a complication of the illness. It was not possible to isolate an agent different from Pneumocystis carinii. Considering the lack of predisposition factors and the previous clinical history, we think that Pneumocystis carinii is by itself the agent responsible of this complication. In view of this possibility, spontaneous pneumothorax in a patient who belongs to an AIDS' risk group will alert the clinician to the possibility of infection with Pneumocystis carinii.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Effects of some adenosine analogs on morphine-induced analgesia and tolerance.

1. The analogs of adenosine D- and L-phenylisopropyladenosine (D- and L-PIA) and chloroadenosine (CADO) induced analgesia in mice (hot-plate test). 2. The antinociceptive effects of the three adenosine agonists were antagonized by caffeine but were unaffected by naloxone. 3. Morphine-induced antinociception was increased by pretreatment with adenosine agonists. 4. Whereas CADO significantly attenuated the induction of morphine tolerance, D- and L-PIA did not affect the process.

2-Chloroadenosine↗
PubMed1990

Influence of adenosine analogs on morphine tolerance and dependence in mice.

A number of adenosine agonists were investigated for possible actions on tolerance to morphine withdrawal in mice. The induction of tolerance to a sustained release preparation of morphine was assessed by measuring the analgesic effect induced by a test dose of the drug. The concomitant treatment with L- and D-phenylisopropyl adenosine, (L- and D-PIA), cyclopentyladenosine (CPA) or chloroadenosine (CADO) during the period of morphine absorption did not alter the induction of the process. In contrast cyclohexyladenosine (CHA) significantly decreased the intensity of tolerance. The administration of naloxone 30 hrs, after the priming dose of morphine induced an intense withdrawal reaction. The intensity of the abstinence syndrome was decreased by the administration of L-PIA, CHA or CADO; CPA and D-PIA were ineffective. These results suggest that adenosine analogs may interfere with the known morphine effects on calcium disposition in nerve terminals.

Adenosine↗
PubMed1989

A comparison of GABAergic influences on the analgesic responses to morphine and pentazocine.

1. The interactions of three GABAergic compounds, gamma-acetylenic GABA, gamma-vinyl GABA and ethylenediamine with the analgesic effects of morphine and pentazocine were examined in mice using the hot plate and tail immersion tests. 2. A significant increase in reaction time induced by morphine was noted in the tail immersion test after pretreatment with the drugs acting through GABA functions. 3. The inhibitors of GABA transaminase, gamma-acetylenic GABA and gamma-vinyl GABA, and the GABAmimetic ethylenediamine did not significantly change the analgesic action induced by pentazocine. 4. In the hot plate test the three GABAergic compounds antagonized the analgesic effects of pentazocine in contraposition with previous results indicating that morphine-induced analgesia is increased by pretreatment with those agents. 5. These findings suggest that GABAergic and opiopeptidergic systems are interconnected through mu receptors, whereas the kappa opiate systems seem to be unrelated to GABA functions.

4-Aminobutyrate Transaminase↗
PubMed1988

Peripheral neuropathy in essential mixed cryoglobulinemia.

Sixteen patients with essential mixed cryoglobulinemia were studied and followed up clinically and electrophysiologically for 4.2 years. Peripheral neuropathy was diagnosed in seven cases. Five of these patients had distal symmetrical sensorimotor polyneuropathy. Nerve conduction velocities were normal and therefore indicative of pure axonal neuropathy. Sural nerve biopsy showed moderate loss of myelinated axons in two patients and severe loss in one. This patient also had necrotizing arteritis. The remaining two had both clinical and electrophysiologic signs of overlapping mononeuritis multiplex with severe denervation in the territory of the involved nerves, but normal conduction velocities. Sural nerve biopsy in one of these two patients showed marked loss of myelinated fibers and signs of vasculitis. Two types of neuropathy were noted: (1) a mild distal neuropathy with relatively minor neurologic deficit, probably due to vasa nervorum microcirculation occlusion caused by intravascular deposits of cryoglobulins and (2) a severe distal symmetrical sensorimotor neuropathy or overlapping mononeuritis multiplex, associated with necrotizing vasculitis.

Adult↗
PubMed1988

Mechanisms of the contractile responses to morphine of the mouse colon in vitro.

1. Morphine induced a contractile response in the mouse colon which consisted of two phases or components. 2. The first component was dose-related and was inhibited by tetrodotoxin, atropine and naloxone, but was insensible to hexamethonium, propranolol, phentolamine, diphenhydramine and methysergide. 3. The second component of the contractile effect was not modified by atropine, hexamethonium, propranolol, phentolamine, guanethidine or diphenhydramine, but was antagonized by naloxone, tetrodotoxin and serotonin antagonists. 4. Tachyphylaxis was observed only for the first component of the morphine induced contractile response of the mouse colon.

Animals↗
PubMed1987

Increase of galanin-like immunoreactivity in rat dorsal root ganglion cells after peripheral axotomy.

The L4 and L5 dorsal root ganglia were studied in untreated rats and rats subjected to unilateral transection of the sciatic nerve, using the indirect immunofluorescence technique and antibodies to the peptide galanin (GAL). In control rats only low numbers of small ganglion cells contained GAL-like immunoreactivity (LI). After axotomy a marked increase in the number and intensity of GAL-immunoreactive ganglion cell bodies was seen on the lesion side. Thus, some primary sensory neurons react to transection of their peripheral branches by expressing increased GAL levels. A similar reaction has been described by other groups for vasoactive intestinal polypeptide.

Animals↗
PubMed1987

Incompatibility in Populus: structural and cytochemical characteristics of the receptive stigmas of Populus alba and P. nigra.

Structural and cytochemical characteristics of stigmas of Populus alba (section Leuce) and P. nigra (section Aigeiros) have been studied to provide an understanding of the cell biology of the interspecific incompatibility reactions between these two species. In addition to specific morphological characteristics, stigma surfaces differ in the presence of an exudate studied by ultrastructural and stigma print techniques. P. nigra shows features of a dry-type stigma covered by a pellicle, whereas P. alba has a copious exudate typical of a wet-type stigma that contains unsaturated lipids.

Histocytochemistry↗