Histamine and increased ovarian blood flow mediate LH-induced superovulation in the cyclic hamster

Abstract

Constant infusion of LH (400 micrograms NIH-S24) through an osmotic minipump inserted on Day 1 (oestrus) of the cycle in the hamster resulted in spontaneous superovulation (approximately equal to 29 ova) at the next expected oestrus, increased blood flow (P less than 0.001) to the ovary on Day 3, and slight depletion (0.1 greater than P greater than 0.05) of histamine in the ovary. Treatment with antihistamine (alpha-fluoromethylhistidine, an irreversible inhibitor of histidine decarboxylase, or cimetidine, an H2 blocker) by injections or by infusion using separate osmotic minipumps significantly (P less than 0.01) reduced the number of ova shed in the LH-treated hamsters. Infusion of LH with alpha-fluoromethylhistidine in the same osmotic minipump reduced the bioactivity of the LH. Infusion of antihistamine alone did not alter the normal number of ova shed. The results suggest that the LH-induced superovulation involves stimulation of histamine release; the histamine than may increase ovarian blood flow thus allowing more gonadotrophins to reach the ovary.

Effect of oestradiol treatment on mast cell populations and microflora in the vaginal cul-de-sac of seasonally anoestrous brushtail possums (Trichosurus vulpecula)

“…For example, a correlation between oestrogen concentration and histamine production by mast cells has been reported during embryo implantation in rats (Ferrando and Nalbandov, 1968). Similar relationships between reproductive status and numbers of mast cells in reproductive tissues have been reported in eutherian species, in which degranulation is associated with increased vascularization of the tissue ( Jones et al, 1980;Krishna and Terranova, 1985;Krishna et al, 1986Krishna et al, , 1989.…”

“…Furthermore, the decrease in mast cell density may be due to cellular degranulation, after which the cells would no longer be distinguishable by histological staining. Mast cell degranulation under the influence of elevated oestrogen may result in histamine release from the cell granules (Krishna and Terranova, 1985;Krishna et al, 1986;Wilhelm et al, 2000). For example, a correlation between oestrogen concentration and histamine production by mast cells has been reported during embryo implantation in rats (Ferrando and Nalbandov, 1968).…”

Changes in Nitric Oxide Synthase Activity in the Ovary of Gonadotropin Treated Rats. The Role of Nitric Oxide during Ovulation.

“…Continuous LH infusion induces superovulation in cyclic hamster, in which it is thought that LH induces vasodilation and thus more FSH can reach growing follicles [23]. Mast cells existing in the ovary release histamine for vasodilation in response to LH [24], but LH could not directly release histamine (unpublished data; Nakamura and Terranova). Substance P, which exists in the ovary [25], has a histamine releasing effect [26], and is also known to induce NO production in the arteries [27].…”

Ovariectomy improves neovascularization and microcirculation of freely transplanted ovarian follicles

“…These observations can in part be interpreted as an adaptive response to high pro-angiogenic stimuli due to supranormal gonadotropin levels. However, increased follicular blood flow might, in particular, be the response upon release of potent vasoactive substances, such as prostaglandins and histamine, known to be also released under high gonadotropin levels (Krishna et al 1986, Brannian & Terranova 1991. With higher blood perfusion, delivery of gonadotropins to the follicles may be increased, facilitating enhanced follicular development (Krishna et al 1986).…”