Microinjection of Urotensin II into the Pedunculopontine Tegmentum Leads to an Increase in the Consumption of Sweet Tastants

Publication date: Available online 13 December 2019Source: Physiology & BehaviorAuthor(s): Robert Ettaro, Tamara Markovic, Derek Daniels, Duncan AA MacLaren, Stewart D ClarkAbstractThe pedunculopontine tegmentum (PPTg) plays a role in processing multiple sensory inputs and innervates brain regions associated with reward-related behaviors. The urotensin II receptor, activated by the urotensin II peptide (UII), is selectively expressed by the cholinergic neurons of the PPTg. Although the exact function of cholinergic neurons of the PPTg is unknown, they are thought to contribute to the perception of reward magnitude or salience detection. We hypothesized that the activation of PPTg cholinergic neurons would alter sensory processing across multiple modalities (ex. taste and hearing). Here we had three aims: first, determine if cholinergic activation is involved in consumption behavior of palatable solutions (sucrose). Second, if so, distinguish the impact of the caloric value by using saccharin, a zero calorie sweetener. Lastly, we tested the UII-mediated effects on perception of acoustic stimuli by measuring acoustic startle reflex (ASR).Male Sprague-Dawley rats were bilaterally cannulated into the PPTg, then placed under food restriction lasting the entire consumption experiment (water ad lib.). Treatment consisted of a microinjection of either 1μL of aCSF or 1μL of 10μM UII into the PPTg, and the rats were immediately given access to either sucrose or saccharin. For the re...
Source: Physiology and Behavior - Category: Physiology Source Type: research