Sex differences in anxiety after infusion of group I mGluR agonist within the basolateral amygdala

Abstract

Females are twice affected by anxiety‐related disorders than males. These differences might be due to the effects of gonadal hormones. Metabotropic glutamate receptors (mGluRs) have been implied in the pathophysiology of anxiety. We hypothesized that S‐3,5‐Dihydroxyphenylglycine (DHPG), a group I mGluRs agonist, within the basolateral amygdala (BLA) will modulate anxiety according to sex. Intact males were compared to ovariectomized female rats that contained empty implants (OVX) or implants containing estradiol (OVX‐EB). We used the Vogel Conflict Test (VCT) to analyze conflict‐based anxiety and the Cat Odor Test (COT) for innate anxiety behaviors. In the VCT, intact males displayed more punished licks than OVX female rats (p=0.05). DHPG infusion did not alter any VCT parameter in intact male, OVX and OVX‐EB female rats. In COT, intact males showed lesser number of flat back approached (FBA) and spent more time in contact with the cat odor stimuli than OVX female rats (p= 0.01 & 0.04). DHPG infusion decreased FBA (p=0.02) and stretch attended behaviors in OVX female rats only (p=0.03). In males, DHPG reduced the number of freezing behaviors (p=0.004). Our results indicate sex differences in anxiety‐related behaviors which are task‐dependent. Infusion of DHPG within BLA modulates innate anxiety behaviors in OVX female rats. We concluded that mGluRs might be a pharmacological alternative to modulate anxiety.