Ganglionic transmission is a prerequisite for the adrenaline-releasing and hyperglycemic effects of 8-OH-DPAT.
The present study concerned the influence of ganglionic nicotinic blockade (by hexamethonium, 5 mg/kg and 10 mg/kg) of the 8-OH-DPAT-induced elevations in plasma adrenaline, corticosterone and glucose levels in conscious rats. Prior treatment with hexamethonium dose dependently decreased the basal glucose levels and increased the basal corticosterone levels but did not significantly affect the basal adrenaline levels. Hexamethonium decreased in a dose-dependent manner the elevations in plasma adrenaline, corticosterone and glucose levels that were elicited by the 5-HT1A receptor agonist, 8-OH-DPAT (0.25 mg/kg). These results indicate that acetylcholine release is a prerequisite for both the adrenaline-releasing and hyperglycemic effects of 8-OH-DPAT. The data also point to the possibility that adrenaline release participates in the elevation in plasma corticosterone levels that is elicited by 5-HT1A receptor activation.