Respiratory, Analgesic and Endocrine Responses to an Enkephalin Analogue in Normal Man

Abstract

In a controlled study, the effect of a new enkephalin analog (FW 34-569, N-methyl-L-tyrosyl-D-ananylglycyl-N-methyl-L-phenylalanine ((S)-1-hydroxy-4-(methylsulfinyl)-2-butyl)amide hydrochloride) on respiratory function (ventilatory response to CO2), pain threshold (hot plate technique) and plasma cortisol, prolactin, growth hormone, luteinizing hormone (LH) and FSH was investigated in 6 normal subjects. Enkephalin, 1 mg but not 0.5 mg, resulted in a significantly decreased ventilatory response to CO2, although mean values were not significantly different from saline control values (0.05 < P < 0.1). Neither 0.5 nor 1.0 mg enkephalin influenced pain threshold, but both doses stimulated growth hormone and prolactin release and inhibited the release of cortisol and LH, while FSH remained unchanged.