Relationship between cerebrospinal fluid β-endorphin and plasma pituitary-gonadal hormone levels in women

Brain β-endorphin (β-EP) plays an important role in regulating the hypothalamus-pituitary-gonadal axis activity. Cerebrospinal fluid (CSF) β-EP levels seem to reflect the central rather than pituitary secretion. With the aim to correlate the changes of plasma estradiol (E2), progesterone, luteinizing hormone (LH) and follicle-stimulating hormone with brain β-EP, CSF levels of β-EP were measured in 15 normally cycling and 15 postmenopausal women. CSF β-EP levels in post-menopausal women were lower than in fertile women. A positive correlation between plasma E2 and CSF β-EP level was found in all women. In fertile women CSF β-EP levels were inversely correlated to plasma gonadotropin levels. These results showed that CSF β-EP levels differ between fertile and postmenopausal women and are correlated with plasma LH and E2, suggesting a strong linkage between central β-EP levels and pituitary-gonadal axis hormones.