The Impact of Epilepsy on Reproductive Functions

1.1 Regulation of female reproductive system Regulation of female reproductive system consists of very complex interactions between the hypothalamus, neurohypophysis and ovaries. Beginning from the embryologic stage, female reproductive system is regulated by the brain. Ovarian hormone production is supressed by the hypothalamo-hypophyseal control mechanism till the end of the childhood period when the puberty begins. During puberty, menstrual cyclicity and timely ovulation, which are the result of the precise integration within different components of the reproductive system, are achieved. After puberty, comes the reproductive period which generally lasts about 30-35 years. During reproductive period, from daily social behavior to sexual life and reproduction, many important issues depend on normal ovarian folliculogenesis and hormonogenesis. Menopause refers to the final menstrual period accompanying the permanent cessation of ovarian function and menstruation. Gonadotropin releasing hormone receptor (GnRHR) is secreted from hypothalamus and delivered to the anterior pituitary via the hypophyseal portal circulation where it binds to the GnRHR on the surface of gonadotropes triggering the synthesis and secretion of the gonadotropins, follicle stimulating hormone (FSH) and luteinizing hormone (LH). In the female, LH stimulates the production of androgens by the thecal cells that surround the growing ovarian follicle. During the terminal stages of follicular growth, LH also drives the production of progesterone from the granulosa cells of the preovulatory follicle. FSH binds to receptors on the surface of ovarian granulosa cells stimulating the expression of aromatase enzymes that convert thecal androgens to estradiol. The Hypothalamushypophysis-gonadal (HPG) axis is subject to both positive feed-forward and negative feedback regulation at several levels. At the level of the hypothalamus, early recognition of the pulsatile nature of gonadotropin releasing hormone secretion led to the notion of a central ‘‘pulse generator”, the inherent oscillatory activity of which controls the secretory rhythm of GnRH neurons (Knobil, 1980). Hypothalamic pulse generator is extensively modulated by a multitude of higher level inputs including photoperiod, environmental stress, metabolic state and nutritional status, as well as various endocrine mediators. (Bliss, 2010)