Taste reactivity alterations after streptozotocin microinjection into the mediodorsal prefrontal cortex

The mediodorsal prefrontal cortex (mdPFC), as an integrant part of the forebrain glucose-monitoring neural network, plays important roles in neural control of feeding. Previous studies suggested that streptozotocin (STZ) causes selective destruction of forebrain glucose-monitoring (GM) neurons leading to development of feeding disturbances. The goal of this research was to evaluate gustatory consequences of bilateral streptozotocin microinjection into the mediodorsal prefrontal cortex of male Wistar rats during conditioned taste avoidance (CTA) acquisition, as well as during taste reactivity tests. Bilateral streptozotocin microinjection failed to impair CTA learning, tested in a saccharin CTA paradigm. However, taste reactivity deficit was found by a modified version of the protocol introduced by Grill and Norgren. The streptozotocin treated animals displayed significantly poorer ingestive reactions to pleasant taste stimuli than did rats of the control group. The unpleasant taste stimuli elicited ingestive and rejective taste reactivity patterns in a comparable manner in rats of the STZ vs. vehicle microinjected groups. The glucose-monitoring neurons of the mdPFC and their distinct role in the gustatory perception may have particular significance in the adaptive control of feeding.