Role of Myocardial Infarction-Induced Neuroinflammation for Depression-Like Behavior and Heart Failure in Ovariectomized Female Rats

After myocardial infarction (MI), ovariectomized (OVX) female rats develop depression-like behaviors and an increase of pro-inflammatory cytokine (PIC) levels in the prefrontal cortex (PFC). We hypothesized that inhibition of neuroinflammation by the PIC synthesis inhibitor, pentoxifylline (PTX) would prevent depression-like behaviors induced by heart failure (HF) post-MI in OVX female rats. PTX treatment was initiated in female Wistar rats, 1 week after ovariectomy, and 1 week before MI by occlusion of the left anterior descending artery. Eight weeks post-MI, OVX female rats treated with vehicle or PTX exhibited a similar MI size and degree of cardiac dysfunction. OVX female rats post-MI developed depression-like behaviors consisting of anhedonia, despair behavior and enhanced freezing behavior in the cued conditioning test. PTX prevented the depression-like behavior symptoms and enhanced freezing. Cytokine levels were elevated in plasma and both paraventricular nucleus (PVN) and PFC, and the mature brain-derived neurotrophic factor (mBDNF) was decreased in the PFC of OVX female rats post-MI. PTX treatment limited the decrease of mBDNF, and decreased cytokine levels in plasma, PVN and PFC to (below) sham levels. These findings show that OVX female rats post-MI exhibit an increase in both peripheral and central inflammation. PTX treatment prevents increases in PIC levels in plasma and PVN but does not attenuate the progression of cardiac dysfunction. In contrast, PTX prevents enhanced PIC production in the PFC, as well as limits depression-like behaviors induced by MI in OVX female rats.