title: (+)-N-allylnormetazocine enhances N-acetyltransferase activity and melatonin synthesis: preliminary evidence for a functional role of sigma receptors in the rat pineal gland.
abstract: In the present study, to evaluate the role that sigma receptors play in the physiology of the pineal gland, we assessed the effects of the sigma receptor ligand (+)-N-allylnormetazocine on the gland activity during either the day or the night. As compared to saline, (+)-N-allylnormetazocine enhanced the physiological increases in both pineal N-acetyltransferase (NAT) activity and melatonin content at night, but it did not affect the biosynthetic activity of the gland during the day. Moreover, (+)-N-allylnormetazocine potentiated the enhancement of NAT activity and pineal melatonin content induced by isoproterenol administration during the day. The nocturnal stimulation of pineal NAT activity and melatonin levels by (+)-N-allylnormetazocine was prevented by pretreatment with rimcazole, a specific sigma receptor antagonist. These results demonstrate that sigma receptor activation by (+)-N-allylnormetazocine is not able, by itself, to stimulate pineal melatonin production, whereas it potentiates the biosynthetic activity of the pineal gland when this is stimulated noradrenergically.
mesh_terms: D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism*; D002227:Carbazoles / Q000494:pharmacology; D008297:Male; D008550:Melatonin / Q000096:biosynthesis*; D010620:Phenazocine / Q000031:analogs & derivatives* / Q000494:pharmacology; D010870:Pineal Gland / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017480:Receptors, sigma / Q000502:physiology*
chemical_list: D014150:Antipsychotic Agents; D002227:Carbazoles; D017480:Receptors, sigma; C012134:SK&F 10047; C034931:rimcazole; D001191:Arylamine N-Acetyltransferase; D010620:Phenazocine; D008550:Melatonin