Neuroendocrine features of pubertal development in females with mental retardation

In order to evaluate the hypothalamic-pituitary effects of mental retardati on during pubertal development,follicle-stimulating hormone (FSH) and lutei nizing hormone (LH) responses to gonadotropin-releasing hormone (GnRH) admi nistration were evaluated at various pubertal stages in a female population with mental retardation (MR) compared to a healthy control group of adoles cents. Fifty-six girls aged 8-16 years with MR and 146 normal females of the same age participated in the study. The analyzed subjects were divided into diff erent pubertal stages, ranging from P2 to P5, in line with their degree of sexual maturation. Each patient underwent a GnRH test (100 mug); blood samp les were collected basally and 15, 30, 60, 90 minutes after the GnRH inject ion. FSH and LH were assayed in each sample; the gonadotropin response to G nRH administration was evaluated as incremental area. No differences were f ound at any pubertal stage between the two studied groups with regard to th e age, body mass index, or age at menarche. Patients with mental retardatio n during stages P2 and P3 showed lower FSH secretion in response to GnRH bo lus compared with control subjects (P2, p < 0.05; P3, p < 0.01). In conclusion, our data show that MR is related to an impaired response of the FSH-secreting pituitary cells to their appropriate stimulus; this featu re is present only in the initial pubertal stages, whereas it disappears du ring sexual development.