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Biomedical subjects

R J Naylor

Publications and source records attributed to R J Naylor.

At least 271 records · Page 15Linked to original sources
PubMed1975

Dyskinetic phenomena caused by the intrastriatal injection of phenylethylamine, phenylpiperazine, tetrahydroisoquinoline and tetrahydronaphthalene derivatives in the guinea pig.

The intrastriatal injection of dopamine-like compounds in the guinea pig caused the development of abnormal involuntary movements (dyskinesias) which were observed as facial grimacing, biting/gnawing/licking, severe hear and neck twisting, limb movements, whole body rocking, head and neck rocking and marked locomotor hyperactivity. With the exception of the whole body and head and neck rocking movements the dyskinesias were specifically induced by dopamine-like agents. The most conspicuous dyskinesias which followed the administration of phenylethylamine derivatives were the movements of biting/gnawing/licking and the development of marked locomotor hyperactivity. This effect was shown to be highly specific for dopamine. Tetrahydroisoquinohydroxy-1,2,3,4-tetrahydronaphthalene (ADTN) caused locomotor hyperactivity and gnawing/biting/licking dyskinesias. Of all compounds investigated 1-(3,4-dihydroxyphenyl)pierazine (DHPP) induced the most marked dyskinetic disturbances upon intrastriatal injection: intense facial grimacing, biting/gnawing/licking, head and neck twisting and limb movements were observed although the locomotor hyperactivity was absent. Of the 1-phenylpiperazine derivatives examined, dyskinetic activity was only demonstrated using compounds with a hydroxyphenyl substitution. Results are discussed in terms of the structure--activity relationships for the stimulation of different types of dopamine receptive structures within the neostriatum.

Animals↗
PubMed1975

The importance of extrapyramidal function for the induction and antagonism of harmine tremor.

The brain lesion technique was used to investigate the role of the paleostriatum and the nigro-neostriatum in harmine-induced tremor and in its antagonism by dopaminergic agonists, apomorphine, 1-dopa, piribedil, d- and l-amphetamine. Bilateral lesions of the caudate--putamen or substantia nigra failed to modify the intensity of tremor or its antagonism by dopaminergic agonists. Bilateral lesions of the globus pallidus markedly reduced the intensity of tremor and the results indicated that such lesions were also able to reduce the effectiveness of dopaminergic agonists as tremor antagonists. The data suggest that the integrity of the paleostriatum is more important than that of the neostriatum for the mediation of harmine tremor and its antagonism by dopaminergic agonists. The results are discussed in relation to the proposed clinical relationship between paleostriatal dopamine dysfunction and tremor mechanisms.

Alkaloids↗
PubMed1975

The behavioural effects of dopamine applied intracerebrally to areas of the mesolimbic system.

The intracerebral injection technique was used to apply dopamine directly into dopamine-containing areas of the mesolimbic system, the nucleus accumbens septi, tuberculum olfactorium and nucleus amygdaloideus centralis. 200 mug dopamine injected bilaterally into the nucleus accumbens septi caused a stereotyped sniffing behaviour and hyperactivity but only a periodic hyperactivity developed after similar injections into the tuberculum olfactorium and no change in behaviour was observed following injections into the nucleus amygdaloideus centralis. After pretreatment with nialamide, the effects of intracerebral dopamine were enhanced, doses of 1-50 mug dopamine causing consistent stereotyped sniffing and a dose-dependent hyperactivity on injection into the nucleus accumbens septi or tuberculum olfactorium. The effects initiated from the nucleus accumbens septi were most marked. In addition, 50-100 mug dopamine injected into the tuberculum olfactorium caused a periodic biting behaviour. Biting was not observed after injections into the nucleus accumbens septi and, even in the presence of nialamide, injections of dopamine into the nucleus amygdaloideus centralis failed to cause any change in motor behaviour.

Animals↗
PubMed1975

N-Isopropyl derivatives of dopamine and 5,6-dihydroxy-2-aminotetralin.

Secondary and tertiary amino homologs of the title compounds have been prepared, bearing an N-isopropyl group. In peripheral evaluation, certain members of the series exhibited beta-adrenergic agonist effects of lower activity than isoproterenol. N-Methyl-N-isopropyl-5,6-dihydroxytetralin exhibited marked properties consistent with its being an alpha agonist, and it is concluded that introduction of considerable bulk about the nitrogen of a catecholamine does not a priori destroy alpha-agonist effects. The compounds qualitatively paralleled the effects of dopamine in assays based upon direct intrastriatal administration in rats, although they were less potent than dopamine.

2-Naphthylamine↗