LHRH-Induced facilitation of [(3)H]inositol phosphate formation in hippocampal slices

Stimulation of inositol phosphate accumulation in response to LHRH was studied in hippocampal slices. Incubation of myo-[(3)H]inositol-labeled slices with LHRH (10 nM) resulted in a marked increase in total inositol phosphates measured in the presence of lithium. The most consistent increase occurred in the IP(2) fraction. A behaviorally active fragment [Ac-LHRH(5-10)] also caused an increase in IP accumulation. [Ac-(3)Pro(1),4F-d-Phe(2), d-Trp(3,6)]-LHRH, a potent LHRH antagonist, effectively blocked LHRH-induced IP accumulation but was unable to block the effects of Ac-LHRH(5-l0). These data suggest that LHRH receptors in the hippocampus, like those in the pituitary, are coupled with phospholipase C activation and in addition suggest that more than one form of the receptor may be present in the rat hippocampus.