An interesting observation is that females seem to be much more sensitive to the subjective and neurotoxic effects of MDMA (66). This too is probably related to hormones. Estrogen has a substantial activating effect on 5-HT neurotransmission, upregulating tryptophan hydoxylase, decreasing both 5-HT transporter mRNA and the sensitivity of 5-HT (1A) autoreceptors (67).
66. Liechti ME, Gamma A, Vollenweider FX. Gender differences in the subjective effects of MDMA. Psychopharmacology (Berl). 2001 Mar 1;154(2):161-8.
67. McEwen B. Estrogen actions throughout the brain. Recent Prog Horm Res. 2002;57:357-84.