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Biomedical subjects

S Govoni

Publications and source records attributed to S Govoni.

At least 181 records · Page 10Linked to original sources
PubMed1982

Effects of GTP and sodium on rat striatal dopamine receptors labeled with lisuride.

[3H]Lisuride binding to rat striatal membranes appeared to be stereospecifically displaced by the dopamine antagonist butaclamol. Sodium increased the number of [3H]lisuride binding sites (Bmax) without changing the dissociation constant (Kd). GTP did not affect [3H]lisuride binding characteristics, either with or without sodium. These results suggest that dopamine receptor sites labeled by lisuride are at least in part sodium-dependent, possibly the D2-receptors not involved in adenylate cyclase stimulation.

Animals↗
PubMed1982

Elevation of Met5-enkephalin and beta-endorphin hypothalamic content in rats receiving anorectic drugs: differences between D-fenfluramine and D-amphetamine.

D-Fenfluramine, an anorectic that releases serotonin (5-HT), repeatedly injected in rats (15 mg/kg per day) enhanced the met5-enkephalin and beta-endorphin content of the hyhpothalamus. The onset of this effect was slow, reaching a peak at 5 days; the increase in beta-endorphin gradually declined toward control level while the drug was still being administered although that of met-enkephalin persisted for 15 days. The elevation of the opioid peptide content of the hypothalamus was temporally associated with a slowing in the rate of body weight increase. A transient, small, increase in striatal met-enkephalin content was also induced by repeated D-fenfluramine injections; however the met-enkephalin content of frontal cortex, hippocampus and brainstem was not affected. A modification of the beta-endorphin content of hypothalamus was not seen after acute injection of D-fenfluramine or D-amphetamine but an increase was observed during repeated treatment with D-fenfluramine. Repeated injections of D-amphetamine for 5 days (4.5 mg/kg per day) failed to increase either the met-enkephalin or the beta-endorphin content of the hypothalamus. These data suggest that the anorexia elicited by repeated injections of D-fenfluramine but not that elicited by D-amphetamine, includes a participation by hypothalamic and beta-endorphin stores.

Animals↗
PubMed1981

Rat dopaminergic function in the retina during aging.

Parameters of dopaminergic transmission were studied in the retina of mature (3-4 months) and aged (23-24 months) rats. In the retina of senescent rats were found significantly higher dihydroxyphenylacetic acid (DOPAC) levels and a higher number of (3H-)spiroperidol binding sites. We detected also an increase of (3H)- methionine-enkephalin binding sites. The changes in the density of (3H)-spiroperidol and (3H)-Metenkephalin binding sites in the retina are opposite to those observed in the brain of aged rats.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1981

Sex differences in the content of beta-endorphin and enkephalin-like peptides in the pituitary of obese (ob/ob) mice.

The beta-endorphin content in pituitary extracts of male and female obese (ob/ob) and lean (+/?) mice was determined by radioimmunoassay. The amount of beta-endorphin-like material contained in the pituitary of 3-month-old ob/ob male mice is similar to that of lean male mice. In contrast, the pituitary glands of female ob/ob mice have a greater amount of beta-endorphin-like material than lean female mice. To determine with greater precision the molecular nature of the polypeptide that accounts for the increase in beta-endorphin immunoreactivity, the various molecular forms of beta-endorphin immunoreactivity were resolved by Biogel P-30 column chromatography. At least four peaks of immunoreactive material were detected. The first peak elutes in the void volume, and the second and the third peaks appear in the elution volumes of beta-lipotropin and beta-endorphin, respectively. That the material present in the void volume might be proopiocortin is supported by adrenocorticotropic hormone radioimmunoassay. The increased total beta-endorphin immunoreactivity in pituitary glands of ob/ob mice is accounted for mainly by beta-endorphin. The beta-endorphin content of various brain structures of ob/ob mice is similar to that of lean littermates.

Animals↗
PubMed1980

Impairment of brain neurotransmitter receptors in aged rats.

Dopamine and gamma-aminobutyric acid (GABA) receptor functions have been measured in various brain areas of aged rats. [3H] Spiroperidol binding is decreased in various dopaminergic brain areas, particularly in striatum and tuberculum olfactorium. In striatum the number of binding sites for [3H] spiroperidol is similar in both groups of animals, while the affinity is reduced in senescent rats. Moreover, in the pituitary a 50% increase of [3H] spiroperidol binding was detected in the group of senescent animals. On the other hand, [3H] GABA binding is significantly decreased in substantia nigra and hypothalamus of aged rats, while it is unmodified in cerebral cortex, cerebellum, striatum and nucleus accumbens.

Aging↗
PubMed1980

Increase of neurotensin content elicited by neuroleptics in nucleus accumbens.

The content of neurotensin immunoreactive material (neurotensin-IR) of nucleus accumbens increases 16 hr after a single injection of 2 mg/kg i.p. of haloperidol; this increase persists for 8 hr or longer. Repeated injections of 2 mg/kg/day of haloperidol i.p. cause a gradual and progressive increase of neurotensin-IR. From 0.32 pmol/mg of protein, it increases to 0.57 pmol/mg (1 week) to 0.62 pmol/mg (2 weeks) and reaches 0.68 pmol/mg (3 weeks). A significant increase of neurotensin-IR content of nucleus accumbens is obtained with 0.5 mg/kg i.p. daily for 2 weeks. Maximal responses are obtained with 1 mg/kg/day in 3 weeks. The striatal neurotensin-IR content of rats injected for 2 weeks with 1 mg/kg/day of haloperidol is also increased. In these rats, the neurotensin-IR content of preoptic area hypothalamus, septum and amygdala failed to increase. The increase of neurotensin-IR material of nucleus accumbens was elicited also by chloropromazine (6 mg/kg), trifluoroperazine (2 mg/kg) and pimozide (1.5 mg/kg) while promazine (10 mg/kg) and promethazine (25 mg/kg) were ineffective. The increase of neurotensin-IR content caused by haloperidol chloropromazine, trifluoroperazine and pimozide in accumbens and striatum suggests a modulation of neurotensin metabolism, synthesis or utilization directly or indirectly through dopaminergic synapses.

Animals↗