Chronic infusion of Montanoa tomentosa reduces despair-like behavior and activates hypothalamic oxytocin neurons in male Wistar rats

Abstract

Montanoa tomentosa is used in traditional Mexican medicine to treat reproductive and mood disorders. Preclinical studies support the idea that acute administration of M. tomentosa induces an antidepressant-like response that may be related to oxytocin activation in hypothalamic cells, however, it
is unknown whether this behavioral and neuroendocrine effect is maintained when chronically administered. Here, 39 adults male Wistar rats were subjected to two conditions: without and with the forced swimming test (FST). Each group received for 28 consecutive days p.o., vehicle (1 mL/kg);
fluoxetine (1 mg/kg); or M. tomentosa (50 mg/kg). M. tomentosa and fluoxetine treatments significantly decreased the total immobility time compared with that using vehicle without producing any significant change in locomotor activity. No significant between-treatment differences were found in the number of
oxytocinergic neurons, indicating that chronic infusion of M. tomentosa exerts antidepressant-like effects, similar to those of Fluoxetine, independently of oxytocinergic activation.