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Biomedical subjects

A Jori

Publications and source records attributed to A Jori.

At least 37 records · Page 2Linked to original sources
PubMed1977

Tolerance to the increase of striatal homovanillic acid elicited by several anorectic drugs.

Several anorectic drugs affect dopamine metabolism in the rat striatum, increasing the concentration of homovanillic acid (HVA). However 1- and d-amphetamine and mazindol develop a tolerance to the HVA increase. On the contrary, the effect of fenfluramine and S 992 is not reduced by sub-chronic treatments. Moreover, a cross-tolerance to this biochemical effect develops between amphetamine and mazindol, but pretreatment with fenfluramine or with S 992 does not induce cross-tolerance to amphetamine.

Animals↗
PubMed1977

Possible storage of (+)-amphetamine in catecholaminergic terminals of the striatum and brainstem.

6-Hydroxydopamine, given intraventricularly, did not affect the high concentrations of (+)-amphetamine present in the rat striatum and brainstem 1 h after its administration but considerably reduced the small amounts of (+)-amphetamine remaining after 5 h. In contrast, 5,6-dihydroxytryptamine did not modify the (+)-amphetamine concentrations at the times tested. These findings suggest that (+)-amphetamine might be stored in the catecholaminergic but not in the serotonergic central terminals.

5,6-Dihydroxytryptamine↗
PubMed1977

Biochemical and pharmacological studies on amineptine (S 1694) and (+)-amphetamine in the rat.

The pharmacological activities of amineptine (S 1694) and (+)-amphetamine and their interaction with biogenic amines have been examined in rats. The locomotor activity, stereotyped behaviour and hypothermia induced by amineptine were similar to but not as marked as those produced by (+)-amphetamine, and there was little or no anorectic action. Amineptine does not modify the concentrations of brain noradrenaline or acetylcholine which are respectively reduced and increased by (+)-amphetamine. Moreover, amineptine does not affect significantly the decrease of brain noradrenaline induced by an intraventricular injection of 6-hydroxydopamine, an effect significantly antagonized by (+)-amphetamine. On the other hand, like amphetamine, amineptine significantly reduces the effect of 6-hydroxy-dopamine on brain dopamine. Both drugs increase the striatal concentrations of homovanillic acid and show a cross tolerance in this action. Therefore they could act similarly on the striatal dopaminergine system. Amineptine thus appears to be a new type of antidepressant with a brain biochemical profile differing from that of other drugs used in depressive disorders.

Animals↗
PubMed1976

Increase in striatal acetylcholine by picrotoxin in the rat: evidence for a gabergic-dopaminergic-cholinergic link.

Picrotoxin, 2 mg/kg i.p., a GABA receptor blocking agent, increased rat striatal acetylcholine content by approximately 70% without altering the levels of this amine in the cerebral hemispheres, mesencephalon, diencephalon, hippocampus and cerebellum. Striatal choline levels were concomitantly decreased by about 25%. This dose of picrotoxin also increased striatal homovanillic acid levels by about 30%, an effect which was not antagonized by pretreatment with the dopamine receptor stimulating agent, piribedil. Picrotoxin did not affect striatal choline-O-acetyltransferase or cholinesterase activity after in vitro incubation. The action of picrotoxin on striatal acetylcholine levels was partially antagonized by pimozide and completely blocked by alpha-methyl-para-tyrosine pretreatment while the intraventricular injection of 6-hydroxydopamine was without effect. Convulsions were not prevented by any of these treatments. The results are interpreted as follows: picrotoxin released dopamine through disinhibition of the dopaminergic neurons as a result of blockade of gabergic receptors. The increased dopaminergic activity inhibited cholinergic neurons and lead to an increase in acetylcholine content. The data thus provide evidence for a possible gabergic (inhibitory)--dopaminergic (inhibitory)-cholinergic link terminating in the striatum.

Acetylcholine↗
PubMed1976

Effects of contraceptive agents on drug metabolism in various animal species.

The effect on liver microsomal enzyme activity of three steroid contraceptive drug (SCD) combinations was compared in rats, mice and guinea-pigs. Lynestrenol plus mestranol, norethisterone plus mestranol and norethynodrel plus mestranol were given orally for 4 consecutive days (acute treatment) or 30 days (chronic treatment) at various doses eliciting an experimentally controlled antifertility activity which varied in its extent. In rats and mice all the combined treatments (with the exception of norethynodrel plus mestranol in mice) were active as inducers of liver microsomal enzymes. This induction seems to be mediated mainly by the progestogenic compounds. Oestrogens showed a very poor effect bordering on significance only in a few cases. No effect on liver microsomal protein or cytochrome P 450 concentration was obtained after treatment with doses capable of increasing the microsomal enzyme activity. The activity of the liver microsomal enzymes did not appear to be reduced immediately (2 h) after the last administration of the SCD given during 4 or 30 days. Contraceptive treatments at doses capable of eliciting complete antifertility activity were inactive on liver microsomal enzyme activity in guinea-pigs.

Animals↗
PubMed1976

Modifications of striatal dopamine levels by steroid contraceptive drugs in mice and rats.

The effect of steroid contraceptive drugs (SCDs) on the concentration of dopamine (DA) in the striatum was studied in mice and rats. Mestranol was combined with each one of the three progestins, lynestrenol, norethindrone and norethynodrel. Treatments were given daily for 1, 4 or 30 days; animals were sacrificed 1 or 18 h after the last administration. In all groups, with the exception of the animals sacrificed 1 h after an acute treatment, striatal DA was significantly lower than in controls.

Animals↗
PubMed1976

Modifications of the striatal dopamine metabolism during the estrus cycle in mice.

The metabolism of striatum dopamine (DA) was studied in mice during proestrus, estrus and diestrus. The following results have been obtained: (1) the concentration of DA is higher in diestrus than in proestrus and estrus; (2) the concentration of its metabolite, homovanillic acid (HVA), is maximum in the estrus phase; (3) the DA turnover, evaluated by measuring the DA disappearance after blocking synthesis with methyltyrosine, is faster in estrus than in the other phases. These results have been discussed in view of the possible role of dopaminergic mechanisms in the control of gonadotropin secretion.

Animals↗
PubMed1976

Biochemical effects of treatment with oral contraceptive steroids on the dopaminergic system of the rat.

The effects of acute and chronic administration of a combination of lynestrenol-mestrenol, a widely employed contraceptive medication, on the dopaminergic system of the rat forebrain and striatum were investigated to better understand the biochemical basis of the neurological side-effects of steroid contraceptive drugs (SCDs). Both acute and chronic treatment increased the disappearance rate of striatal dopamine (DA) after synthesis blockade with alpha-methyl-p-tyrosine (alpha-MpT). Moreover, the conversion of 3H-tyrosine (3H-T) into 3H-DA was increased in the forebrain and striatum after chronic administration of this steroid combination. In the same animals, the utilization of tyrosine (T) is increased.

Animals↗
PubMed1975

Effect of ECT and imipramine treatment on the concentration of 5-hydroxyindoleacetic acid (5HIAA) and homovanillic acid (HVA) in the cerebrospinal fluid of depressed patients.

The influence of probenecid administration on 5HIAA and HVA concentrations in the CSF of depressed patients, was studied before and after treatment with imipramine or ECT. The average increase of the two metabolites in the CSF after probenecid was similar in the untreated depressed patients and in the same patients improved after both imipramine or ECT treatment. The treatment determined a significant increase in the CSF concentration of the acid metabolites also before the probenecid administration.

Adult↗