Glucocorticoids impair maternal anxiolysis during lactation.

Lactating female rats show a maternal anxiolysis signal, which is part of the behavioral pattern that develops post-partum and seems to be related to hormonal changes during lactation. Assuming that glucocorticoids modulate prolactin and oxytocin secretion, we evaluated the effect of dexamethasone on behavior responses of fear and anxiety in lactating rats. For this study, the non-lactating and lactating rats were submitted to an elevated T-maze and open field tests. In the elevated T-maze, the lactating rats showed a decrease in inhibitory avoidance and an increase in the escape time when compared with the non-lactating group. The lactating rats that had been treated with dexamethasone showed increased initial avoidance latency when compared with lactating rats treated with vehicle. The same result was found in the subsequent repetitions (avoidance 1 and 2). In addition, there was a reduction in one-way escape time for the lactating rats that were treated with dexamethasone. The lactating rats treated with vehicle had increase of number central entries, and consequently, the anti-thigmotactic effect increased relative to non-lactating rats. Thus, lactating rats showed a reduced emotional responsiveness as evaluated by elevated T-maze and open field tests, which characterizes maternal anxiolysis. In addition, it could be concluded that the dexamethasone impairs maternal anxiolysis in lactating female rats.