Thyrotropin-releasing hormone and the menopausal hot flash

The possibility that the sudden discharge of thyrotropin-releasing hormone (TRH) in the brain triggers the climacteric hot flash was tested (double-blind) by an intra-venous, bolus injection of 500 microgram of TRH into 7 post-menopausal women and 1 menstruating control. Temperatures and sweating were recorded continuously on the recumbent subject during the 2-h test. None of the women reacted either subjectively or objectively to the placebo. TRH induced gastric pain in 1 post-menopausal subject. In another subject TRH elicited no response during the first test, but a week later in a second test it evoked transient nausea and a series of hot flashes with bursts of sweating. Published results of animal studies suggest that a higher dose of TRH would probably stimulate hot flash-like responses in more women.