Conclusions
Beneficial anxiolytic-like actions of MT are observed under low hormone conditions, particularly in the PW challenge (a condition that can be related to a premenstrual period). Furthermore, the participation of the GABAA receptor is evidenced. However, hormonal variations could induce the opposite effects, hence women should be cautious.
Methods
The animal model of anxiety used was the elevated plus-maze (EPM). Rats' endocrine conditions were: a) Low hormone levels (rats in diestrus I and II phases); b) High hormone levels (proestrus/estrus phases); c) No hormones (ovariectomized rats); and d) Rats under progesterone withdrawal (PW). To evaluate the participation of the GABAA receptor in the anxiolytic-like action of MT the antagonist picrotoxin was used.
Results
Results showed that MT induced dose-dependent anxiolytic-like actions in rats with low hormone level conditions. Also, MT reduced anxiety-like behavior in female rats under PW, in contrast to diazepam which was ineffective. MT's anxiolytic-like effect was blocked by picrotoxin, suggesting the participation of the GABAA receptor complex. However, increased anxiety-like behavior was observed in rats with a high hormone level condition and low doses of MT. Conclusions: Beneficial anxiolytic-like actions of MT are observed under low hormone conditions, particularly in the PW challenge (a condition that can be related to a premenstrual period). Furthermore, the participation of the GABAA receptor is evidenced. However, hormonal variations could induce the opposite effects, hence women should be cautious.