Monoamine oxidase A is highly expressed by the human corpus luteum of pregnancy

Neuromodulatory effect of GnRH from coeliac ganglion on luteal regression in the late pregnant rat

The GnRH/GnRH receptor system has been found in several extrapituitary tissues, although its physiological significance has not yet been well established. Taking into account that the peripheral neural system can act as a modulator of pregnancy corpus luteum, the objective was to physiologically investigate the presence of the GnRH system in coeliac ganglion (CG) and to analyse its possible involvement in luteal regression through the superior ovarian nerve (SON) at the end of pregnancy in the rat. The integrated ex vivo CG-SON-Ovary system of rats on day 21 of pregnancy was used. Cetrorelix (CTX), a GnRH receptor antagonist, was added into the ganglionic compartment while the control systems were untreated. Ganglionic GnRH release was detected under basal conditions. Then, the CTX addition in CG increased it, which would indicate the blockade of the receptor. In turn, CTX in CG caused an increase in ovarian progesterone release. Furthermore, the luteal cells showed an increase in the expression of Hsd3b1 and a decrease in the expression of Akr1c3 (progesterone synthesis and degradation enzymes, respectively), reduced TUNEL staining according to an increase in the antioxidant defence system activity and low lipid peroxide levels. The ovarian and ganglionic nitric oxide (NO) release increased, while the luteal nitrotyrosine content, measured as nitrosative stress marker, decreased. CTX in CG decreased the ovarian noradrenaline release. The present study provides evidence that GnRH from CG may trigger neuronal signals that promote the luteal regression in late pregnancy by affecting the release of NO and noradrenaline in the ovary.

Activity of Monoamine Oxidases in Rat Female Genital Organs During Preimplantation Period of Pregnancy

Our objectives in the present study were to determine the activity of monoamine oxidases A and B (MAO AB) in rat ovary, oviduct and uterus during preimplantation period of pregnancy. It should help us to clarify and better understand possible involvement of both MAO enzymes in the reproductive process. Pregnant females were killed employing a lethal dose of thiopental on the first (D1), on the third (D3), and on the fifth (D5) days of pregnancy. Rats were perfused transcardially with the PBS to rinse out of the body as much blood as possible. Ovaries, oviducts and uteri were immediately removed and stored until the measurement was done. MAO activity was determined by fluorescent monoamine oxidase detection kit. In the ovaries we have found the highest MAO activity at D3, followed by D1, and the lowest levels were recorded at D5 of pregnancy. In the oviducts, the highest MAO activity was detected again at D3, followed by D5, and by D1 of pregnancy. But statistical analysis did not reveal any difference between individual days of pregnancy nor in the ovaries, neither in uterine tubes. Uteri were the only organs, in which statistically significant differences were detected (p<0.001). The highest activity of MAO was observed at D5, followed by D1, and by D3 of pregnancy. Potential mechanisms responsible for the changed MAO activity in gonads during preimplantation period of pregnancy are proposed.