Sexual dimorphism modulates brain histamine functions at multiple sites

Sexual dimorphism has been demonstrated in rat brain and the ovarian steroids affect H₁ and H₂ histaminergic binding sites as demonstrated with ³H]-mepyramine and ³H]-histamine, respectively. The evaluation of histamine release, related to the presynaptic H₃ receptors, from cortical slice preparations reveals hyposensitive releasing activity in the female rat compared to the male, both after KCl-induced histamine release and after inhibition of histamine release by (R)-methylhistamine (H₃ selective agonist). Therefore, we may suggest a global hyposensitivity of the histaminergic neural system in female rats under the modulation of ovarian sexual steroids.