1. (+)-N-allylnormetazocine enhances N-acetyltransferase activity and melatonin synthesis: preliminary evidence for a functional role of sigma receptors in the rat pineal gland
- Author
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Luca Steardo, Monteleone, P., D Istria, M., Serino, I., Maj, M., Cuomo, V., Steardo, L, Monteleone, P, D'Istria, M, Serino, Ismene, Maj, Mario, and Cuomo, V.
- Subjects
Male ,Arylamine N-Acetyltransferase ,Carbazoles ,DISCRIMINATIVE STIMULUS PROPERTIES ,BRAIN ,RIMCAZOLE ,Pineal Gland ,Rats ,Rats, Sprague-Dawley ,Phenazocine ,Animals ,Receptors, sigma ,Antipsychotic Agents ,Melatonin - 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.
- Published
- 1995