Effect of ovarian hormones on intestinal mast cell reactivity to SubstanceP

Evidence exists to support the concept that ovarian hormones influence mast cell functioning and related events. Here, we evaluated the constitutive S ender 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 r elease were found in female compared with male. In female rats, hormonal st atus did not affect the density of resident MC neither in the jejunum nor i n the colon. Interestingly, histamine levels released after SP stimulation of jejunal segment was reduced in ovariectomized (OVX) compared with sham O VX rats, and restored in OVX female receiving progesterone. In the colon, O VX resulted in a significant increase in histamine levels released after SP stimulation and a treatment with progesterone did not restore basal histam ine levels. Thus, ovarian steroid hormones do not affect jejunal and coloni c mast cell number. However, the hormonal status differently influences jej unal and colonic MC sensitivity to SP. (C) 2001 Elsevier Science Inc, All r ights reserved.