ABSTRACT
I. INTRODUCTION Prolactin (PRL) is secreted mainly by the anterior pituitary gland and is a major vehicle in the neuroendocrine communication system. It relays messages from the brain, through the hypothalamus, in response to various endogenous or exogenous stimuli, to a large number of target tissues, including the immune system. After hypophysectomy in the rat, PRL levels are very low. At the same time, profound immune deficiencies are present. These deficiencies can be prevented by various protocols of hormone replacement, such as treatment with PRL only. Updated information on PRL can be retrieved via Refs. 1 and 2.
