Metabolic influences on hypothalamic-pituitary-ovarian function in the pig.

A relationship between nutrition and reproduction hag been known to exist for a considerable time, aIthough the physiological mechanisms mediating these effects are only beginning to be elucidated. Body weight, fatness or body composition have all been suggested to play an important role in the long-term control of reproductive function. However, there is now evidence to indicate that nutritional modulation of the reproductive axis can occur in the absence of any change in body weight or composition and that factors regulating the metabolic status of an animal may provide a link between nutrition and reproduction. These physiological signals appear to involve metabolit hormones and substrates. This review will briefly describe the influence of nutrition on plasma substrate concentrations, metabolic hormones and neurotransmitter activity and the mechanisms by which these physiological signals affect the activity of the hypothalamo—hypophysial—ovarian axis. Subsequently, this paper will review experiments in pigs and other species which have directly investigated the mechanisms by which manipulation of nutrition or metabolic status influence reproductive function during the prepubertal period, in sexually mature animals and also during the post-partum period.