Vagal activity has protective effects in ischemic heart disease. We tested whether vagal stimulation (VS) could modulate the inflammatory reaction, a major determinant of cardiac injury after ischemia/reperfusion. Four groups of male rats underwent myocardial ischemia (30 minutes) and reperfusion (24 hours). One group underwent VS (40 minutes), 1 VS plus atrial pacing (VS + Pacing), and 1 VS plus nicotinic inhibition by mecamylamine (VS + MEC). After 24 hours, the area at risk, infarct size, inflammation parameters, and apoptosis were quantified. Infarct size was reduced in all VS-treated rats (controls, 53 ± 18%; VS, 6.5 ± 3%; VS + Pacing, 23 ± 6%; VS + MEC, 33 ± 9%; P < 0.005 vs. controls). The infarct size in the VS + MEC group was larger than that in VS-treated animals, despite similar heart rate, suggesting partial loss of protection. The number of macrophages, neutrophils, and apoptotic cells in the area at risk and the plasma cytokines levels were significantly reduced in all VS-treated animals. In conclusion, VS decreases infarct size and inflammatory markers during ischemia/reperfusion independent of the heart rate. The anti-inflammatory and antiapoptotic properties of the nicotinic pathway are the primary underlying mechanism. The vagally mediated modulation of inflammatory responses may prove valuable in the clinical management of acute coronary syndromes and of heart failure.

Stem cells have been increasingly recognized as a potential tool to replace or support cells damaged by the neurodegenerative process that underlies Parkinson's disease (PD). In this frame, human adult mesenchymal stem cells (hMSCs) have been proposed as an attractive alternative to heterologous embryonic or neural precursor cells. To address this issue, in this study we implanted undifferentiated hMSCs into the striatum of rats bearing a lesion of the nigrostriatal pathway induced by local injection of 6-hydroxydopamine (6-OHDA), a widely recognized rodent model of PD. Before grafting, cultured hMSCs expressed markers of both undifferentiated and committed neural cells, including nestin, GAP-43, NSE, β-tubulin III, and MAP-2, as well as several cytokine mRNAs. No glial or specific neuronal markers were detected. Following transplantation, some hMSCs acquired a glial-like phenotype, as shown by immunoreactivity for glial fibrillary acid protein (GFAP), but only in animals bearing the nigrostriatal lesion. More importantly, rats that received the striatal graft showed increased survival of both cell bodies and terminals of dopaminergic, nigrostriatal neurons, coupled with a reduction of the behavioral abnormalities (apomorphine-induced turning behavior) associated with the lesion. No differentiation of the MSCs toward a neuronal (dopaminergic) phenotype was observed in vivo. In conclusion, our results suggest that grafted hMSCs exert neuroprotective effects against nigrostriatal degeneration induced by 6-OHDA. The mechanisms underlying this effect remain to be clarified, although it is likely that the acquisition of a glial phenotype by grafted hMSCs may lead to the release of prosurvival cytokines within the lesioned striatum.

No abstract