We examined the effects of several neuroendocrine agents on the intraceliular cyclic AMP level in cultured monkey trabecular meshwork cells. Among the peptide agonists studied, only the vasoactive intestinal peptide elevated the cyclic AMP level. Alpha-melanocyte stimulating hormone, glucagon, and others showed no stimulation. Prostaglandin E1and L-isoproterenol also enhanced the intraceliular cyclic AMP level. Such effects may implicate physiologic roles of these agonists in the trabecular meshwork.