The role of the histaminergic system in the central cardiovascular regulation in haemorrhagic hypotension.

The histaminergic system consists of neurons located in tuberomammillary nucleus of the posterior hypothalamus. It affects many functions of the central nervous system, including regulation of the brainstem cardiovascular center. In this paper, we present current review of the literature concerning the role of the histaminergic system in the cardiovascular regulation in haemorrhagic hypotension. Experimental studies demonstrate that in both, normotension and critical hemorrhagic hypotension, histamine, acting as a central neurotransmitter, evokes the pressor effect. Interestingly, increases in mean arterial pressure are significantly higher in hypovolaemic than in normovolaemic animals. Many lines of evidence support the hypothesis that in haemorrhagic shock, the histaminergic system is able to activate neural and humoral compensatory mechanisms involving the sympathetic nervous and renin-angiotensin systems, arginine vasopressin and proopiomelanocortin-derived peptides. We suggest that the histaminergic system could be a new target for treatment of hemorrhagic hypotension.