EFFECT OF NEUROPEPTIDES ON COGNITIVE FUNCTION

Decent evidence indicates that, in addition to the involvement of chol inergic and other neurotransmitter systems, various neuropeptides that occur in cortical and subcortical brain regions have a role in cognit ive behavior. This evidence results largely from behavioral studies in rodents and other animals, following peptide administration and only in a very few cases from similar studies in human subjects. Several ne uropeptides studied appear to enhance or produce changes conducive to improvement in cognitive performance and these include vasopressin, co rticotrophin-releasing hormone (CRH), somatostatin, substance P, neuro peptide Y, and thyrotrophin-releasing hormone (TRH), while one peptide , galanin, has been reported to inhibit cognitive processes. Of those neuropeptides that improve performance, only TRH has been shown recent ly to attenuate the memory impairment of human subjects and Alzheimer patients treated with an anticholinergic drug, and this review describ es a series of complimentary studies in adult and aged rodents that co ntribute to our understanding of the possible mechanisms involved in t he role of TRH in cognition. (C) 1997 Elsevier Science Inc.