Changing neuroendocrine function during aging: Impact on diurnal and pulsatile rhythms

Several aspects of hypothalamic regulation of hormone secretion by the anterior pituitary gland change with age. Virtually all pituitary hormones are secreted in a pulsatile manner and exhibit a diurnal rhythm. Hence, age-related changes occur not only in the average concentration of a hormone, but also in its diurnal and pulsatile pattern of secretion. These changes in rhythmicity play an important role in aging of female reproductive capacity. Accumulating evidence suggests that changes in the release of hypothalamic hormones and in the patterns of neurotransmitter activity occur during aging and may play a major role in reproductive aging by influencing pituitary function and ovarian follicular development and ovulation. We will present evidence that changes in the biological rhythms of hormone secretion and neurotransmitter activity occur during middle age and may contribute to the cascade of interactive events leading to the menopause.