ABSTRACT
Numerous reports have appeared which clearly show that prolactin is found in the cerebrospinal fluid (CSF), especially in that of humans and other primates. Rats with very high serum prolactin due to pituitary tumors also have elevated prolactin levels in the CSF. There is a significant amount of evidence showing a correlation between peripheral and CSF blood levels of prolactin in monkeys and humans. Several experiments have been done in rhesus monkeys in which a stimulus to release prolactin was given and the CSF and blood levels of prolactin monitored over time. Acute elevations in plasma prolactin were followed by a similar, slow increase in prolactin in the CSF. The brain is exposed to prolactin even though prolactin is secreted by the anterior pituitary. Prolactin is found in the cerebrospinal fluid and may even be produced by neurons in the hypothalamus, or reach the hypothalamus by way of retrograde blood flow in the hypophysial portal vessels.
