Diagram illustrating the regulation of reproductive endocrinology in intact ferrets, the consequences of neutering on this process, and the possible role it plays in the development of hyperadrenocorticism in this species. In short, high melatonin concentrations for >12 hours per day suppress the release of GnRH. When this suppression is lost, GnRH is released in a pulsatile fashion, resulting in the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which in turn stimulate the release of estrogen and testosterone. This exerts a negative feedback on the hypothalamus and pituitary gland. When ferrets are neutered this negative feedback is lost, resulting in an increased release of the gonadotrophins, which may activate their respective receptors in the adrenal glands of the ferret (if present in these glands).
Courtesy of Dr. N. J. Schoemaker.