Peripheral chemoreceptors mediate training-induced plasticity in paraventricular nucleus pre-autonomic oxytocinergic neurons

Josiane C. Cruz, Marina T. Cavalleri, Alexandre Ceroni and Lisete C. Michelini February 1, 2013 Experimental Physiology, 98, 386-396. Previously this laboratory showed that sino-aortic denervation prevented the training induced plasticity. So they investigated the effects of chemoreceptor denervation and on cardiovascular system and on oxytocin gene and protein expression in Paraventricular nucleus (PVN) in SHRs and WKYs that were either sedentary or exercise trained. They measured resting and baroreflex and peripheral chemoreceptor reflex responses. They chemo-denervated rats and assessed treadmill performance along with HR, BP, chemoreceptors responses, baroreceptor responses, along with mRNA and protein expression of oxytocin in PVN. They found that HR was significantly reduced in trained when compared to sedentary rats in SHAM group. However, in the chemo-denervated group the reduced HR response seen in the trained group was not present. Oxytocin mRNA expression in the PVN was upregulated in the sham exercise trained group when compared to the sham sedentary group. In the chemo- denervated rats the oxytocin mRNA was not significantly different between groups. There was increased oxytocin immunoreactivity in the medial and posterior PVN in the sham SHR exercise trained rats when compared to sham SHR sedentary rats. The chemoreceptor reflex is playing an important role in exercise induced changes in PVN oxytocinergic neurons.-MD