A recently published study reported that a methanol extract of vitex had affinity to the (.i-opiate receptor (Webster et al 2006). Of note, this receptor is the primary action site for beta-endorphin in vivo, a peptide which assists in regulating the menstrual cycle through inhibition of the hypothalamus-pituitary- adrenal axis.
Clinical note — The opiate system and PMS
The opiate system consists of mu, delta and kappa opiate receptors and endogenous opiate peptides such as beta-endorphin (Webster et al 2006). The opiate system plays an essential role in regulating tonic pain perception, mood, appetite, and other functions. PMS is characterised by a reduction of opiate activity and the severity of symptoms such as anxiety, food cravings, and physical discomfort is inversely proportional to the amount of decline in beta-endorphin levels in the luteal phase. Based on recent research, the symptom-relieving effects of vitex in PMS may be due to direct activation of analgesic and mood regulatory pathways via opiate receptor activation and/or reversal of the loss of opiate inhibition in the luteal phase.
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