Effects of [D-Ala2, D-Leu5]enkephalin and [D-Pen2, L-Pen5]enkephalin on apomorphine-induced motor activity in the mouse.
The effects of intracerebroventricular injections of opioid peptides such as DADL [( D-Ala2, D-Leu5]enkephalin) and DPLPE [( D-Pen2, L-Pen5]enkephalin) with different degrees of selectivity for delta- over mu-receptor on apomorphine (0.1, 0.3, 1.0 and/or 3.0 mg/kg)-induced motor activity were investigated in the mouse using multi-dimensional behavioral analyses. Lower doses (0.1 and 0.3 mg/kg) of apomorphine failed to affect significantly motor activity, whilst higher doses (1.0 and 3.0 mg/kg) of the drug produced a marked increase in linear locomotion, circling, rearing, and/or grooming behaviors. DADL (0.03, 0.1 or 0.3 microgram) by itself did not influence behaviors, while the peptide (0.1 and 0.3 microgram) produced a marked inhibition on apomorphine (1.0 but not 3.0 mg/kg)-induced increase in rearing behaviors. Furthermore, the inhibitory effect of DADL (0.3 micrograms) on the apomorphine (1.0 mg/kg)-induced increase in rearing was reversed by treatment with the alkylating agent beta-FNA (beta-funaltrexamine) (5.0 micrograms). In contrast to the effects of DADL, the much more delta-selective opioid agonist DPLPE (0.3, 1.0 or 1.75 micrograms) had no marked effects on apomorphine (1.0 mg/kg)-induced behaviors. These results suggest that delta opioid receptors do not play a principal role in the apomorphine-induced increase in circling, rearing or grooming behaviors.
Ukai
M
M
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Meijo University, Nagoya, Japan.
Toyoshi
T
T
Kameyama
T
T
D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D001058:Apomorphine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D020881:Enkephalin, D-Penicillamine (2,5)-; D016308:Enkephalin, Leucine-2-Alanine / Q000494:pharmacology*; D004745:Enkephalins / Q000494:pharmacology*; D006120:Grooming / Q000187:drug effects; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009043:Motor Activity / Q000187:drug effects*; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D011957:Receptors, Opioid / Q000187:drug effects; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D013239:Stereotyped Behavior / Q000187:drug effects
D000700:Analgesics; D004745:Enkephalins; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D009271:Naltrexone; D016308:Enkephalin, Leucine-2-Alanine; C024524:beta-funaltrexamine; D020881:Enkephalin, D-Penicillamine (2,5)-; D001058:Apomorphine