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Biomedical subjects

J S Shaw

Publications and source records attributed to J S Shaw.

49 records · Page 3Linked to original sources
PubMed1978

In vitro profile of some opioid pentapeptide analogues.

The opiate agonist potency of thirteen synthetic enkephalin pentapeptides has been examined on the electrically stimulated guinea pig ileum and mouse vas deferens preparations in comparison with methionine and leucine enkephalins, beta-endorphin and normorphine. Their antagonism by naloxone (Ke) was also assessed on each preparation. Our findings are compatible with, and are discussed in the context of, the hypothesis that these preparations possess at least two populations of receptors.

Animals↗
PubMed1975

Dopaminergic drugs antagonize the psychotomimetic effects of partial-agonist analgesics.

The psychotomimetic actions of the partial-agonist analgesic drugs cyclazocine and levallophan have been demonstrated using a quantitative behavioural test in young rats which measures lateral head movements and pivoting on the hind paws. This drug induced behaviour is antagonized by low doses of the dopaminergic agonists apomorphine and piribedil, the dopamine releasing drug amphetamine, the dopamine reuptake blocking agent benztropine and by large doses of the dopamine precursor L-Dopa. Naloxone antagonize the behaviour, but only at one hundred times the analgesic antagonist dose. These results show that dopaminergic systems are implicated in the mechanism of action of partial-agonist induced psychotomimetic side effects.

Amphetamine↗
PubMedDate not supplied

Specificity of the opioid affinity reagent, DALECK, in a set of isolated tissue assay systems.

The C-terminal chloromethyl ketone derivative of D-Ala2-Leu5-enkephalin (DALECK) has previously been shown to act as an affinity reagent at opioid receptors. The specificity of this derivative in its reversible interaction with functional opioid receptors has been examined here in a set of four field-stimulated isolated tissue preparations; the mouse, rat and rabbit vas deferens and the guinea pig ileum. Agonist potencies relative to selective reference agonists and Schild analysis were used to elucidate the overall activity of DALECK when interacting reversibly with opiate receptors under normal physiological conditions in the isolated tissue preparations. Under these conditions the ligand shows a very strong mu-selectivity. Data obtained in the guinea pig ileum suggest that DALECK is more potent than Tyr-D-Ala-Gly-N(CH3)Phe-Gly-ol (DAGO) when acting through mu-receptors. In contrast in the mouse vas deferens DALECK is at least 70-fold less potent than the delta-ligand D-Thr2-Leu5-enkephalin-Thr (DTLET). DALECK shows little interaction with kappa-receptors.

Amino Acid Chloromethyl Ketones↗