Histamine H1-receptors modulate somatostatin receptors coupled to the inhibition of adenylyl cyclase in the rat frontoparietal cortex

Abstract Puebla, L., A. OcaNa and E. Arilla. Histamine H 1 -receptors modulate somatostatin receptors coupled to the inhibition of adenylyl cyclase in the rat frontoparietal cortex. Peptides 18 (10) 1569–1576, 1997.—Since exogenous histamine has been previously shown to increase the somatostatin (SS) receptor-effector system in the rat frontoparietal cortex and both histamine H 1 -receptor agonists and SS modulate higher nervous activity and have anticonvulsive properties, it was of interest to determine the participation of the H 1 -histaminergic system in this response. The intracerebroventricular (i.c.v.) administration of the specific histamine H 1 -receptor agonist 2-pyridylethylamine (PEA) (10 μg) to rats 2 h before decapitation increased the number of SS receptors (599 ± 40 vs 401 ± 31 femtomoles/mg protein, p p −4 M) to inhibit basal and FK (10 −5 M)-stimulated AC activity in frontoparietal cortical membranes was significantly higher than in the control group (34 ± 1% vs 20 ± 2%, p 1 -receptor antagonist mepyramine (30 mg/kg, intraperitoneally (IP) prevented the PEA-induced changes in SS binding and SS-mediated inhibition of AC activity. Mepyramine (30 mg/kg, IP) alone had no observable effect on the somatostatinergic system. The in vitro addition of PEA or mepyramine to frontoparietal cortical membranes obtained from untreated rats did not affect the SS binding parameters. Altogether, these results suggest that the H 1 -histaminergic system modulates the somatostatinergic system in the rat frontoparietal cortex.