Effects of GRF (1-29) NH2 on short-term memory: neuroendocrine and neuropsychological assessment in healthy young subjects.

Recent studies seem to indicate that the somatotropinergic system (STS) (GRF-SS-GH-SM axis) may be involved in the neuromodulation of higher activities of the central nervous system (CNS). In an attempt to demonstrate the influence of the STS on memory functions in humans, we have investigated the effects of acute administration of exogenous GRF vs. placebo on short-term memory (STM) in healthy young subjects. We gave GRF(1-29)NH2 (150 micrograms; i.v.) to a group of subjects (EG) (N = 17) and placebo (0.9% saline, 1 ml; i.v.) to a different group of subjects (CG) (N = 6). Prior to testing we presented a list of 20 neutral words (A1), and 2 hours after injection the same list (A2) and another list (B) of similar characteristics were presented in order to evaluate cognitive performance (CP). Basal CP (A1 list) was similar in EG and CG. Differences between EG and CG were found for both A2 (EG = 14.76 +/- 1.55 words vs. CG = 11.83 +/- 1.34 words, p less than 0.01) and B lists (EG = 12.17 +/- 1.68 words, p less than 0.005). According to the basal serum GH levels, EG subjects were divided into 2 subgroups: EG1 (N = 6), with high basal GH levels (11.57 +/- 4.47 ng/ml) and EG2 (N = 11), with low basal GH levels (1.55 +/- 1.71 ng/ml), similar to CG (1.3 +/- 1.53 ng/ml). GRF-induced GH response showed maxima 15 (28.15 +/- 11.71 ng/ml) and 30 min (28.09 +/- 17.07 ng/ml) after injection in EG1 and at 45 min (15.52 +/- 14.45 ng/ml) in EG2.(ABSTRACT TRUNCATED AT 250 WORDS)