This study was aimed at elucidating the possible effects of a large annual variation in photoperiodicity on the secretory activities of the pineal gland, pituitary and testes. Serum daytime melatonin, FSH, LH, prolactin (Prl), testosterone and oestradiol concentrations were determined monthly over a year in 24 healthy young adult men (except for melatonin which was analysed only in 11 subjects) in northern Finland, where the day length is 22 h in mid-summer and 3.5 h in mid-winter. Serum daytime melatonin levels showed two annual peak values, in December and May, and a nadir was observed in August. The absolute values of the other hormones measured did not show significant month to month variation over the observation period. When hormone levels were calculated as percentages of the individual annual means, several significant differences were found between monthly levels. The melatonin peak in May (133 +/- 20%, SE, of the annual mean) was associated with significant increases in LH (110 +/- 4%) and FSH (107 +/- 3%). Prl levels (115 +/- 9%) reached a maximum in January. The nadirs of melatonin and the pituitary hormones measured were seen in August. Oestradiol showed the highest values in April-June, but no significant variation was found in serum testosterone levels. Positive correlations were observed between FSH and LH (r = 0.41, P less than 0.01), and Prl and LH (r = 0.26, P less than 0.01), whereas Prl and testosterone (r = -0.17, P less than 0.01) were inversely correlated.(ABSTRACT TRUNCATED AT 250 WORDS)
Natural exogenous progesterone has been shown to affect the functioning of the central nervous system in man, inducing dizziness and sedation by unknown mechanisms. Seven postclimacteric women known to suffer from dizziness during natural progesterone therapy were treated with a single oral dose of 200 mg of natural progesterone on 2 occasions, with and without preceding administration of indomethacin. Cardiovascular responses, vasoactive prostanoids and catecholamines in the blood, and excretion of prostanoids in the urine were measured. Serum progesterone concentrations increased in each subject, and all the women experienced dizziness or tiredness after progesterone intake. Blood pressure and heart rate did not change. Urine excretion of immunoreactive prostaglandin E2 and 6-keto-prostaglandin1 alpha decreased significantly in the experiment without pretreatment with indomethacin, whereas indomethacin pretreatment reduced the basal excretion of prostanoids and abolished the progesterone-induced decrease in their excretion. The plasma concentrations of prostanoids and catecholamines did not change. The results confirm that natural progesterone can cause dizziness and tiredness in man. The appearance of these symptoms is not related to peripheral vasodilation or to changes in plasma prostanoid or catecholamine levels. Neither are the symptoms related to the alteration in the urinary excretion of prostanoids, since the women still suffered from tiredness and dizziness after pretreatment with indomethacin.