Diazepam augments gender differences in cutaneous LD flux response to local cooling

Cutaneous vasoconstriction in response to local cooling is normally greater in females than in males. Cold induces amplification of alpha2-adrenoceptor affinity for norepinephrine and increases reflex sympathetic thermoregulatory output. Benzodiazepines are drugs with very well-known binding to the central and peripheral benzodiazepine receptors. Besides these effects they decrease sympathetic output and as it was shown in the last decade they act synergistically with alpha-adrenoceptors. In the present study we tested the hypothesis that the benzodiazepine diazepam interacts with an alpha-adrenoceptor mechanism at the level of microcirculation. We measured laser-Doppler blood flux changes provoked by local cooling before and after oral application of a low dose of diazepam (5 mg) in 9 healthy males and in 11 healthy females with regular menstrual cycles. The results of our experiments show that in females there is a significant reduction (ANOVA, p < 0.05) in laser-Doppler flux during the first four minutes of cooling after taking of diazepam. In males, there is no significant difference in the responses to cold before and after an application of diazepam. Our results suggest that diazepam, in addition to its well-known effect on BZ receptors may also interact with alpha2C-adrenoceptors in the vessel wall during local cooling.