Activation of Opioid and Muscarinic Receptors Stimulates Basal Adenylyl Cyclase but Inhibits Ca2+/Calmodulin- and Forskolin-Stimulated Enzyme Activities in Rat Olfactory Bulb
Article first published online: 23 NOV 2002
Journal of Neurochemistry
Volume 63, Issue 1, pages 161–168, July 1994
How to Cite
Olianas, M. C. and Onali, P. (1994), Activation of Opioid and Muscarinic Receptors Stimulates Basal Adenylyl Cyclase but Inhibits Ca2+/Calmodulin- and Forskolin-Stimulated Enzyme Activities in Rat Olfactory Bulb. Journal of Neurochemistry, 63: 161–168. doi: 10.1046/j.1471-4159.1994.63010161.x
- Issue published online: 23 NOV 2002
- Article first published online: 23 NOV 2002
- Received July 13, 1993; revised manuscript received November 15, 1993; accepted November 25, 1993.
- Muscarinic receptors;
- Opioid receptors;
- Adenylyl cyclase;
- Rat olfactory bulb
Abstract: In rat olfactory bulb, muscarinic and opioid receptor agonists stimulate basal adenylyl cyclase activity in a GTP-dependent and pertussis toxin-sensitive manner. However, in the present study, we show that in the same brain area activation of these receptors causes inhibition of adenylyl cyclase activity stimulated by Ca2+ and calmodulin (CaM) and by forskolin (FSK), two direct activators of the catalytic unit of the enzyme. The opioid and muscarinic inhibitions consist of a decrease of the maximal stimulation elicited by either CaM or FSK, without a change in the potency of these agents. [Leu5]Enkephalin and selective δ- and μ-, but not κ-, opioid receptors agonists inhibit the FSK stimulation of adenylyl cyclase activity with the same potencies displayed in stimulating basal enzyme activity. Similarly, the muscarinic inhibition of FSK-stimulated adenylyl cyclase activity shows agonist and antagonist sensitivities similar to those characterizing the muscarinic stimulation of basal enzyme activity. Fluoride stimulation of adenylyl cyclase is not affected by either carbachol or [Leu5]enkephalin. In vivo treatment of olfactory bulb with pertussis toxin prevents both opioid and muscarinic inhibition of Ca2+/CaM- and FSK-stimulated enzyme activities. These results indicate that in rat olfactory bulb δ- and μ-opioid receptors and muscarinic receptors, likely of the M4 subtype, can exert a dual effect on cyclic AMP formation by interacting with pertussis toxin-sensitive GTP-binding protein(s) and possibly by affecting different molecular forms of adenylyl cyclase.