Background:
Post-stroke depression (PSD) occurs in one-third of stroke survivors, is more prevalent in women, and negatively impacts quality of life and recovery. Our previous work showed that acyclic middle-aged female rats display depressive behaviors after stroke, and IV treatment with mir363-3p attenuates these behaviors. Serotonin has been implicated in affective behaviors, and loss of this neurotransmitter is also associated with decreased neurogenesis in the hippocampus. The present study determined (a) whether stroke affected tryptophan, a gut metabolite, and precursor for serotonin, and cell proliferation in the hippocampus and (b) whether serum tryptophan levels and hippocampal cell proliferation was restored by mir363-3p.
Methods:
Ischemic stroke was induced by stereotaxic delivery of endothelin-1 to the MCA of middle-aged female rats. Animals received a single injection of mir363-3p or scrambled oligos 4h after stroke. Depressive-like behaviors were assessed by the Effort-based sucrose consumption test, Social Interaction and Forced Swim Test 3 months after stroke. Blood was collected at termination. Serum tryptophan levels were quantified by ELISA. Bacterial composition was analyzed by 16S sequencing of fecal samples. Ki67 immunohistochemistry was performed on brain tissue collected at termination and quantified within the dentate gyrus by two blind observers.
Results:
Animals subjected to stroke exhibited depressive-like behaviors and had decreased tryptophan levels as compared to sham treated animals. This is also accompanied by microbiota dysbiosis as measured by an elevated ratio of Firmicutes to Bacteroidetes. Mir363-3p treatment increased tryptophan levels as compared to scrambled controls and were no different from sham (non-stroke) animals. Moreover, miR363-3p treated rats exhibit a significantly more dentate gyrus-specific Ki67 expression a proliferation marker.
Conclusions:
Together, these data indicate that miR363-3p attenuates post stroke depression via a mechanism that prevents microbiota dysbiosis and increases hippocampal cell proliferation.
Effects of S-Allyl-L-Cysteine on Cell Proliferation and Neuroblast Differentiation in the Mouse Dentate Gyrus
