Regional blood flow of the mesencephalic ventral tegmental area increases during spontaneous fictive motor activity in decerebrate cats and rats

Abstract

The mesencephalic ventral tegmental area (VTA) has been supposed to play an important role in the central generation of the cardiovascular response to exercise (Nakamoto et al. J Appl Physiol 2011), but whether the neural activity in the VTA increases accompanying the cardiovascular response during exercise remained unclear. The present study aimed to investigate whether the regional blood flow (RBF) in the VTA, which is ascribed to the neural activity, changes in association with the cardiovascular responses during spontaneous fictive motor activity. Cats and rats were decerebrated at the premammillary and precollicular level and then paralyzed. A probe of laser Doppler flowmetry was inserted into the VTA or substantia nigra, and the RBF was measured during 1) fictive motor activity, 2) transient occlusion of the abdominal aorta, and 3) stretching of the triceps surae muscle. RBF of the VTA, but not substantia nigra, increased accompanying a pressor response in all of the three conditions. Importantly, the increment of vascular conductance in the VTA was larger during fictive motor activity as compared to that during muscle stretching, while the vascular conductance decreased during aortic occlusion. The present results indicate that the neural activity in the VTA contributes to the cardiovascular response during fictive motor activity in decerebrate cats and rats.