Vagotomy prevents the effect of probiotics on caspase activity in a model of postmyocardial infarction depression

Abstract

Key Messages• Myocardial infarction induces apoptosis in the amygdala.• Probiotics reverse the increase in caspase activities in the amygdala after MI, and their beneficial outcome is abolished by vagotomy.• This finding underscores vagus nerve involvement in the beneficial effect of probiotics in an animal model of post-MI depression.• Probiotics were administered daily, 14 days before myocardial ischemia and until euthanasia. Vagotomy was induced in designed groups before 40 min of myocardial ischemia. After 3 days of reperfusion activity of the caspase-3 or -8 in the amygdala was determined. AbstractBackground Myocardial infarction (MI) is associated with apoptosis in the amygdala and, ultimately, with clinical signs of depression. Different treatments have proven to be beneficial in preventing depression, including combination of the probiotics Lactobacillus helveticus and Bifidobacterium longum for prophylaxis. We have speculated previously that the benefit of these probiotics is due to their anti-inflammatory properties, and evidence suggests that an intact vagus nerve is important for this effect to occur. This study was designed to ascertain vagus nerve involvement in the beneficial influence of probiotics on caspase activities in our post-MI animal model of depression.Methods Probiotics and/or vehicle were administered daily to male adult rats, 14 days before MI and until euthanasia. Vagotomy was performed in subgroups of rats 40 min before MI. They were sacrificed after 3 days of reperfusion, and MI size was assessed along with caspase-3 and -8 activities in the amygdala. Key Results Probiotics had no effect on infarct size but vagotomy increased it. Caspase-3 and caspase-8 activities in the amygdala were higher in MI than in sham-operated rats, and this outcome was reversed by probiotics. The beneficial influence of probiotics was abolished by vagotomy. Conclusions & Inferences Our data indicate that the effect of probiotics on caspase activities in the amygdala after MI depends on an intact vagus nerve.

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