Prolactin & orgasm in men (NANDI)
Several studies have shown that elevated prolactin is the most consistent neuroendocrine marker of orgasm in men. Since men suffering from hyperprolactinemia generally have depressed libidos, it's been postulated that the prolactin released during orgasm in men is responsible for the "refractory period" during which another orgasm is difficult or impossible to achieve.
In support of this theory the abstract below summarizes a case study that showed a lack of prolactin release in a multi-orgasmic male.
Many people claim that bromocriptine and other dopaminergic agonists which lower prolactin increase their libido. I wonder if bromocriptine blocks the orgasm induced prolactin release as well as lowering basal prolactin levels, allowing a man to achieve multiple orgasms. (I have experimented with bromocriptine and never experienced this effect.)
Int J Impot Res. 2002 Apr;14(2):133-5.
Absence of orgasm-induced prolactin secretion in a healthy multi-orgasmic male subject.
Haake P, Exton MS, Haverkamp J, Kramer M, Leygraf N, Hartmann U, Schedlowski M, Krueger TH.
Department of Medical Psychology, University Clinic of Essen, Germany.
In several studies we have recently demonstrated that orgasm induces prolactin secretion in healthy males and females. This suggests that prolactin may form a feedback regulator of the refractory period following orgasm. To examine this position we investigated the prolactin response of a healthy multi-orgasmic male subject. Blood was drawn continuously during masturbation-induced orgasm. The prolactin response of the case-subject was compared with that of nine healthy adult men with a normal refractory period. The case-subject showed no prolactin response to three orgasms. Data from this multi-orgasmic subject support the hypothesized role of plasma prolactin in contributing to sexual-satiation mechanisms