Role of omentin-1 in susceptibility to anxiety and depression like behaviors.

Neuro-inflammation and blood-brain barrier (BBB) dysfunction are associated with depression. Evidence shows that adipokines enter the brain from the circulation, which regulates depressive behaviors. Omentin-1 is a newly identified adipocytokine that has anti-inflammatory effects, but little is known about its role in neuro-inflammation and mood-relevant behavior. Our results showed omentin-1 knockout mice (Omentin-1-/-) increased susceptibility to anxiety and depressive-like behaviors, which are associated with abnormalities of cerebral blood flow (CBF) and impaired BBB permeability. Moreover, omentin-1 depletion significantly increased hippocampal pro-inflammatory cytokines (IL-1β, TNFα, IL-6), caused microglial activation, inhibited hippocampus neurogenesis, and resulted in autophagy impairment by dysregulating ATG genes. Omentin-1 deficiency also sensitized mice to the behavioral changes induced by lipopolysaccharide (LPS), suggesting that omentin-1 could rescue neuro-inflammation by acting as an anti-depressant. Our in vitro microglia cell culture data confirmed that recombinant omentin-1 suppresses microglial activation and pro-inflammatory cytokine expression induced by LPS. Our study suggests that omentin-1 can be used as a promising therapeutic agent for the prevention or treatment of depression by providing a barrier-promoting effect and an endogenous anti-inflammatory balance to downregulate the proinflammatory cytokines.