Dopaminergic Compounds in Vitex Agnus Castus

Abstract

Ethanolic extracts of the fruits of Vitex agnus castus (AC) are widely used to effectively treat premenstrual symptoms. It was recently demonstrated that premenstrual symptoms, particularly premenstrual mastodynia are often accompanied by a latent hyperprolactinemia [4–6, 12, 16, 17]. Prolactin is a pituitary hormone produced by the so-called lactotropes. When high levels of the hormone circulate in the blood it stimulates lobulo-alveolar growth of mammary tissue and lactation. Hence, in latent hyperprolactinemic patients the mammary gland is unphysiologically stimulated and therefore so tender that each movement of the body or each tactile stimulus results in painful sensations. This latent hyperprolactinemia can be unmasked by injection of metoclopramide, a dopamine receptor blocking drug [5, 16]. Under physiological conditions this will result in prolactin release to values not higher than 4000 to 5000 µU/ml. Under the conditions of latent hyperprolactinemia, values exceeding these can be regularly achieved. Furthermore, latent hyperprolactinemia is often manifest during the time of decreasing progesterone and estradiol values prior to menstruation, i.e., during the premenstrual period [5]. Any stressful condition is also a stimulator of pituitary prolactin release. Hence, it is often observed that women have relatively high prolactin levels upon withdrawal of a blood sample, if a second or third blood sample is withdrawn through indwelling antecubital vein catheters, the serum prolactin levels drop down in most women. This stress response is also augmented in women suffering from latent hyperprolactinemia [5]. Prolactin episodes are also released during deep sleep phases and also these prolactin episodes are higher in amplitude and longer in time in latent hyperprolactinemic women in comparison to normal controls [16].