Effect of ovarian hormones on intestinal mast cell reactivity to substance P.

Evidence exists to support the concept that ovarian hormones influence mast cell functioning and related events. Here, we evaluated the constitutive gender difference and the influence of ovarian status on rat mast cell (MC) distribution in jejunum and colon, histamine synthesis and/or its release elicited by Substance P (SP). Higher mast cell (MC) number and histamine release were found in female compared with male. In female rats, hormonal status did not affect the density of resident MC neither in the jejunum nor in the colon. Interestingly, histamine levels released after SP stimulation of jejunal segment was reduced in ovariectomized (OVX) compared with sham OVX rats, and restored in OVX female receiving progesterone. In the colon, OVX resulted in a significant increase in histamine levels released after SP stimulation and a treatment with progesterone did not restore basal histamine levels. Thus, ovarian steroid hormones do not affect jejunal and colonic mast cell number. However, the hormonal status differently influences jejunal and colonic MC sensitivity to SP.