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Biomedical subjects

C Spyraki

Publications and source records attributed to C Spyraki.

47 records · Page 3Linked to original sources
PubMed1982

Clonidine-induced sedation in rats: evidence for mediation by postsynaptic alpha 2-adrenoreceptors.

The effect of low doses of clonidine on exploration and motility was investigated in rats after destruction of central noradrenergic systems by 6-hydroxydopamine (6-OHDA) or DSP-4. In accordance with previous results, clonidine decreased exploration and motility in control animals. This sedative effect of clonidine was potentiated in animals that suffered selective and extensive depletions of brain NA as a result of neonatal treatment with 6-OHDA. Depletion of NA by administration of DSP-4 to adult animals did not influence clonidine's sedative effects. Yohimbine, but not phentolamine, antagonized clonidine-induced hypomotility both in control and in neonatal 6-OHDA treated groups. The results suggest that clonidine-induced sedation is mediated by postsynaptic alpha 2-adrenoreceptors.

Adrenergic alpha-Antagonists↗
PubMed1982

The effect of DSP-4 on some positively reinforced operant behaviors in the rat.

The effects of a new neurotoxin for noradrenergic (NA) neurons, DSP-4, on the acquisition, retention and extinction of positively reinforced operant responses were studied in rats. The acquisition of an L-shaped runway task for food reward, of a simultaneous light-dark discrimination in a Y-maze task and of a lever press response for food was not affected in DSP-4 treated animals. No deficit in retention behavior was found in the Y-maze task after DSP-4 treatment. The DSP-4 treated animals showed increased resistance to extinction in the L-shaped runway. However, the extinction of the lever press response for food (CRF) was unaffected in the same animals. In accordance with previous results, DSP-4 resulted in a widespread depletion of NA in cortex, hippocampus, cerebellum and spinal cord. One week after the DSP-4 administration, histochemical studies at the light microscopic level indicated that the cell bodies of the locus coeruleus remained intact in DSP-4 treated animals. Desipramine pretreatment provided only partial protection from the neurotoxic effects of DSP-4. The results are discussed in relation to the mechanism by which DSP-4 produced the long-term depletion of central NA ans with reference to the role of central NA neurons in behavior.

Amines↗
PubMed1981

Behavioural evidence for supersensitivity of postsynaptic dopamine receptors in the mesolimbic system after chronic administration of desipramine.

The effects of acute and chronic administration of desipramine (DMI) on a number of behaviors thought to be dependent on central dopaminergic (DA) systems were examined in the rat. Chronic but not acute administration of DMI potentiated the locomotor response to d-amphetamine within a narrow dosage range. The potentiation of the amphetamine response was observed up to 5 days after cessation of chronic DMI but had nearly returned to baseline by 10 days. Neither amphetamine- nor apomorphine-induced stereotypy was affected by chronic DMI. Chronic administration of iprindole but not fluoxetine potentiated amphetamine-induced locomotor activity. Chronic DMI administration did not affect the concentration or distribution of [3H]d-amphetamine in the brain. Furthermore, residual anticholinergic effects of DMI did not appear to be responsible for the potentiated amphetamine response. Chronic administration of DMI did not significantly influence the hypomotility induced by low doses of apomorphine. The increased locomotor activity and rearing produced by moderate doses of apomorphine were significantly increased by chronic DMI administration. The results suggest that chronic DMI may produce supersensitivity of postsynaptic receptors in the mesolimbic DA projection, a system that has been associated with the mediation of amphetamine- and apomorphine-induced increases in locomotor activity. There was no evidence for subsensitivity of presynaptic DA receptors after DMI. The findings are discussed with reference to the possible role of central DA neurons in the antidepressant mechanism of action of the tricyclic compounds.

Animals↗
PubMed1980

Effects of diazepam-infrasounds combination on locomotor activity and avoidance behaviour of rats.

The locomotor activity, the two-way conditioned avoidance response, the norepinephrine and dopamine brain levels, were simultaneously studied in rats, under the influence of Diazepam alone or in combination with infrasound environment. Diazepam decreased the spontaneous activity and facilitated the retention of an avoidance behaviour of rats subjected to four shuttle box sessions. These effects were reversed when Diazepam was administered to rats exposed to infrasound environment. The norepinephrine and dopamine levels, determined in whole brain homogenate, were slightly affected in both cases.

Acoustic Stimulation↗
PubMed1980

Pharmacological activity of new derivatives of morphine.

Three new derivatives of morphine: O3-(beta-isopropylaminoethyl) ether of morphine (T .3289), O3, O6-[N,N'-bis(methylcarbamate] ester of morphine (T .3298) and beta-dimethylamino-ethyl-ether of dihydromorphinone (T .3403) were tested for their action on CNS. A detailed study of pain threshold, motor activity, conditioned behavior and noradrenaline levels in brain was carried out. The compounds T .3289 and T .3298 exhibited analgesic action. The spontaneous activity of rats was decreased by T .3289 and increased by T .3298. The conditioned avoidance response was decreased and the brain nor-adrenaline levels were altered.

Analgesics↗