Acute effect of an infusion of Montanoa tomentosa on despair-like behavior and activation of oxytocin hypothalamic cells in Wistar rats

BACKGROUND AND AIM: In Mexican traditional medicine, Montanoa tomentosa (Mt) has been used as a remedy for reproductive impairments and mood swings. In pre-clinical research, both the extract and some of its active metabolites have produced oxytocinergic-like effects on female reproductive organs; however, there are no detailed studies of its effects on mood swing and brain structures. The aim of this study, was to analyze the behavioral effects of acute administration of a Mt infusion on male rats, during the Open Field (OFT) and Forced Swim (FST) Tests, and their association with the activation of oxytocin (OXT) cells, indicated by Fos protein (Fos/OXT) in the paraventricular (PVN) and supraoptic nuclei (SON). EXPERIMENTAL PROCEDURE: 52 adult male Wistar rats were assigned to two conditions; with FST (n = 8), or without (n = 5). Each integrated condition included four groups [Control, Vehicle, Fluoxetine (Flx; 10 mg/kg), and Mt (50 mg/kg), p.o.]. RESULTS AND CONCLUSION: Mt and Flx treatment produced an anti-despair-like effect on the FST, but no significant changes in locomotor activity. Also, the Mt infusion -but not Flx-significantly increased the number of Fos/OXT cells in the PVN and SON, regardless of the condition, compared to the control and vehicle groups. These results show that Mt, but not Flx, produces an anti-despair-like effect that could be associated with the activation of OXT cells in PVN and SON. This study thus contributes to our knowledge of the pharmacological activity of Mt infusions, which could be a natural antidepressant agent with future clinical relevance.