Chapter 15 Functional recovery from neuroendocrine deficits: studies with the hypogonadal mutant mouse

Abstract

This chapter discusses the effect on the reproductive physiology of the hypogonadal male host of grafts, containing GnRH cells that were obtained from a region not known to project to the median eminence, and the effect of preoptic area grafts placed in the lateral ventricle far from the median eminence. The chapter also presents measurement of plasma luteinizing hormone (LH) in relation to mating in hypogonadal females with preoptic area grafts to determine the presence of an ovulatory LH surge in mutant animals with preoptic area grafts. The ability of preoptic area grafts to correct deficiencies in reproductive development is an important example of successful neural transplants, demonstrating that grafted neuropeptide-secreting cells may survive, develop axonal projections into the appropriate region of the host brain, and secrete their products in a physiological manner. Graft tissue derived from neonatal mouse brain appears to result in as frequent and vigorous correction of reproductive deficiencies as does tissue derived from fetal brain. Anatomical studies confirm that there are synapses onto gonadotropin hormone-releasing hormone (GnRH) perikarya and dendrites within the grafts, although whether the source is intrinsic or extrinsic to the grafts is not yet defined.