Mastication Accelerates Rehabilitation of Brain Function after Cerebral Infarction

Objectives: Masticatory function has been suggested to improve brain function by increasing blood flow, numbers of ChAT-positive neurons, ACh levels and so on. Yet the improvements in brain function that are supposedly associated with mastication may actually be caused by food intake, which is demonstrably associated with improvements in ability to perform activities after stroke. The process of brain rehabilitation is too poorly understood for this question to be easily resolved. In this study, we investigated whether solid feeding or liquid feeding was associated with greater functional recovery from learning/memory dysfunction, induced by cerebral infarction, among rats. Methods: Thirty male Wistar/ST rats were subjected to middle cerebral artery occlusion or sham surgery. After these operations, all rats were given liquid feed for 14 days. Rats were then divided into two groups: a solid-feeding group and a liquid-feeding group. The effect of mastication on the recovery of learning and memory skills was evaluated by means of a Y-maze task and a step-through passive avoidance task. Results: In the Y-maze task, the total arm entries were equal in both groups, but alternation behavior was significantly more common in the solid-feeding group. Furthermore, in the step-through passive avoidance task, rats in the liquid-feeding group exhibited significantly longer escape latencies on day 3 of the trials. Conclusion: This study suggests that the mastication required by a solid diet could contribute to the rehabilitation of learning/memory dysfunction induced by cerebral infarction. Many stroke patients may require prosthodontic treatments to allow them to consume a solid diet and benefit from the associated improvements in brain function.