Menstrual Cycle and Ovarian Hormone Effects on Plasma and Platelet Monoamine Oxidase (MAO) and Plasma Dopamine-Beta-Hydroxylase (DBH) Activities in the Rhesus Monkey

Abstract

Dopamine-B-hydroxylase (DBH) and monoamine oxidase (MAO) in plasma and platelets were studied in six female rhesus monkeys during three complete menstrual cycles. The same monoamine enzymes of seven bilaterally ovariectomized females were compared with a group of controls. A difference was found in platelet MAO between a mid-menstrual-cycle peak and a perimenstrual trough in these animals, while plasma MAO was unchanged. DBH showed an inverted cyclical variation to that demonstrated by platelet MAO. The ovariectomized females showed significant differences from the controls, confirming the effects of the ovarian sex steroid hormones on platelet MAO and plasma DBH. The variation in these peripheral enzymes may be reflective of changes in brain monoamine systems, which may play some role in the behavioral changes observed during the menstrual cycle in primates.

Platelet Monoamine Oxidase in Women with Premenstrual Syndrome

“…The present finding is therefore only suggestive o f a difference in menstrual cycle pattern o f platelet M AO in women with premenstrual syndrome compared with normals. However, the consistency o f previous findings o f men strual (11)(12)(13) or estrus (10,12) variations o f human platelet, monkey platelet and rat tissue MAO supports the interpretation that the present clinical group is different in their MAO pattern. It is unlikely that the differences can be attri buted to the tryptamine substrate used in the study of Belmaker et al (11), since Redmond et al (13) used benzylamine as in the present study and very high correlations of tryptamine and benzylamine activities are reported (21).…”

“…There was no difference in the pattern of platelet MAO or RBC COMT activity in those women temporarily asymptomatic compared to those women who were symptomatic during the study. Figure 2 reproduces previous reports o f premenstrual decline in platelet MAO from humans (11) and monkeys (13). Monkey platelet MAO shows a 21% decline, the nadir being 1-5 days before onset o f menses.…”

“…Belmaker et al (11) reported a decline in human platelet MAO in the prementstrual period, as did Southgate et al (12). Redmond et al (13) found a similar prementstrual decline in platelet M AO from rhesus monkeys.…”

“…Each sample was assigned a menstrual cycle date based on the number o f days before the next menstrual flow , as in other reports (11,13). In one case a sample taken 10 days before menses in a women whose symptoms had commenced was included in the premen strual group o f samples for data analysis.…”

Plasma DBH, Platelet MAO and Proteins of Red Blood Cell Membranes in Individuals with Variants of the Normal EEG

“…In order to rule out possible hormonal influences due to men strual cycle (Redmond et al, 1975) or contraceptive use in females, we examined male carriers of the EEG variants only. The 4 groups (a-d ) of variant carriers consisted of 15 students (mean age ± SD 26.9 t 3.8 years) for group a, 18 students (25.8 ± 3.0 years) for group b, 24 students (26.2 t 1.7 years) for group c, and 18 students (25.9 ± 3.3 years) for group d. Plate let MAO activity and proteins of red blood cell mem branes were examined in the groups a, b, and d only, which consisted of 10, 12, and 13 students, respec tively.…”