Mobilization of the innate immune response by a specific immunostimulant β-glucan confers resistance to chronic stress-induced depression-like behavior by preventing neuroinflammatory responses

•Pre-injection of β-glucan prevents CUS-induced depression-like behaviors.•The 10-day interval abolishes the preventive effect of β-glucan on depression.•A second β-glucan injection still has a preventive effect on depression.•Repeated β-glucan injections 10 days before stress exposure prevent depression.•Immune inhibition cancels the preventive effect of β-glucan on depression.