Neuroendocrinology its product?" and "how is information encoded in electrical activity?"[It appears that this is a primary source observation.] The pituitary gland is divided into two sections: the anterior pituitary and the posterior pituitary. The hypothalamus controls the anterior pituitary's hormone secretion by sending trophic hormones down the hypothalamohypophysial portal system. For example, thyrotropin-releasing hormone stimulates the secretion of thyroid-stimulating hormone by the anterior pituitary. The posterior pituitary is innervated by the hypothalamus; the hormones oxytocin and vasopressin are synthesized by neuroendocrine cells in the hypothalamus and stored at the nerves' ends in the posterior pituitary. They are secreted directly into
Pituitary pars intermedia dysfunction by corticotropes in the pars distalis of the equine pituitary. In a normal horse, this accounts for the majority of ACTH production. ACTH produced by the pars distalis is subject to negative feedback in a normal horse, so high cortisol levels reduce ACTH production by the pituitary, subsequently reducing cortisol levels. In a horse with PPID, ACTH levels are high as a result of pars intermedia production, but it is not subject to negative feedback regulation. Despite the high levels of ACTH, cortisol levels vary, and are sometimes lower than normal. Additionally, hyperplasia of the adrenal cortex is infrequent. The