Exercise enhances motor skill learning by neurotransmitter switching in the adult midbrain.

Physical exercise promotes motor skill learning in normal individuals and those with neurological disorders but its mechanism of action is unclear. We find that one week of voluntary wheel running enhances the acquisition of motor skills in normal adult mice. One week of running also induces switching from ACh to GABA expression in neurons in the caudal pedunculopontine nucleus (cPPN). Consistent with regulation of motor skills, we show that the switching neurons make projections to the substantia nigra (SN), ventral tegmental area (VTA) and ventrolateral-ventromedial nuclei of the thalamus (VL-VM). Use of viral vectors to override transmitter switching blocks the beneficial effect of running on motor skill learning. We suggest that neurotransmitter switching provides the basis by which sustained running benefits motor skill learning, presenting a target for clinical treatment of movement disorders

Neuronal activity regulates neurotransmitter switching in the adult brain following light-induced stress.

Neurotransmitter switching in the adult mammalian brain occurs following photoperiod-induced stress, but the mechanism of regulation is unknown. Here, we demonstrate that elevated activity of dopaminergic neurons in the paraventricular nucleus of the hypothalamus (PaVN) in the adult rat is required for the loss of dopamine expression after long-day photoperiod exposure. The transmitter switch occurs exclusively in PaVN dopaminergic neurons that coexpress vesicular glutamate transporter 2 (VGLUT2), is accompanied by a loss of dopamine type 2 receptors (D2Rs) on corticotrophin-releasing factor (CRF) neurons, and can lead to increased release of CRF. Suppressing activity of all PaVN glutamatergic neurons decreases the number of inhibitory PaVN dopaminergic neurons, indicating homeostatic regulation of transmitter expression in the PaVN

Solid-liquid Two-phase Flow Numerical Simulation around Guide Vanes of Mixed-flow Water Turbine

AbstractBased on the N-S control equation and κ-ɛ-Ap turbulent model, the solid-liquid two-phase flow field around the guide vanes of a mixed-flow water turbine was simulated. The solid-liquid two-phase flow characters around the guide vanes were analyzed on the design work condition with different volume fraction and particles diameter of solid phase. The effects of the solid particles diameter and volume fraction on the flow around the guide vane are discussed, based on which the prediction and analysis of abrasion and cavitation properties on the guiding device were given. The prediction results were identical with the test date, which can provide reference on the abrasion prediction and optimal design of guide vane