The effects of dopaminergic pathway on mean relative gene expressions of ghrelin and neuropeptide Y in induced polycystic ovarian syndrome model rats

Nezhaddadgar, Leila (2018) The effects of dopaminergic pathway on mean relative gene expressions of ghrelin and neuropeptide Y in induced polycystic ovarian syndrome model rats. Masters thesis, University of Mohaghegh Ardabili.

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Abstract

Disorders of tonic and surge secretion of gonadotropin releasing hormone (GnRH) and luteinizing hormone (LH ) is one of the most important causes of infertility and anovulation in Polycystic ovary syndrome (PCOS). The secretion of these hormones is under control of several peripheral hormones and intra hypothalamic neuropeptides including ghrelin, NPY, kisspeptin and so on. ghrelin inhibits both type of GnRH/LH secretion. Neuropeptide Y stimulates surge secretion of LH while it inhibits GnRH/LH tonic secretion. Previous studies have shown that dopamine stimulates ghrelin secretion but it exerts inhibitory effects on NPY synthesis. Dopamine release is lower in PCOS women compared to healthy individuals. In the present study the effects of L-dopa and dopamine receptor antagonists were investigated on relative ghrelin and NPY gene expressions in the ovary and hypothalamus of PCOS model rats. The PCOS rats in three groups received saline, L-dopa(100mg/kg), simultaneous injections of sulpride(10mg/kg), SCH23390 hydrochloride (1mg/kg) and L-dopa(100mg/kg) via intraperitoneal injection respectively. Also, intact estrous rats as a control group received saline intraperitoneally. Hypothalamus and ovary samples were dissected. Mean relative ghrelin and NPY gene expressions were determined by real- time-PCR method. The data were analyzed by SPSS software and using independent t-test and one- way ANOVA followed by post hoc Tukey test. In all cases, significance was defined by p≤0.05. The results showed that injections of L-dopa did not significantly increase the mean relative ovary ghrelin gene expressions in comparison to PCOS rats. But it significantly decreases hypothalamic kisspeptin and NPY gene expressions in comparison to PCOS rats. Also, injections of L-dopa following the D1-Like and D2-like dopamine receptor antagonists named sulpride and SCH23390 did not significantly increase the mean relative NPY gene expressions compared to L-dopa group. Increasing the Dopaminergic neurons activity may be clinically useful in treatment and the understanding of the infertility mechanism of PCOS via regulating the synthesis of different neuropeptides of its neuroendocrine axis.

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