A Study On The Impact Of Dietary Restriction On The Response Property Of V1 Neurons And The Underlying Mechanisms

A considerable number of investigations have reported that dietary restriction(DR)or calorie restriction can significantly retard aging and extend life span.However,the underlying physiological and cellular mechanisms remain in debating.Although it has been reported that dietary restriction affects neuronal plasticity in the cortex,results regarding the effects of DR are inconsistent.To clarify these issues,we examined the response property of neurons in the primary visual cortex(V1)of DR and control groups of cats using in vivo extracellular single-unit recording techniques,and assessed the synthesis of inhibitory neurotransmitter GABA in V1 of cats from both groups using immunohistochemical and Western blot methods.Our results showed that the response of V1 neurons to visual stimuli was significantly modified by DR,as indicated by an enhanced selectivity for stimulus orientations and motion directions,decreased visually-evoked response,lowered spontaneous activity and increased signal-to-noise ratio in DR cats relative to control cats.Further,accompanied with the changes of neuronal responsiveness,GABA immunoreactivity and the expression of key GABA-synthesizing enzyme GAD67 in V1 were significantly increased by DR.These results demonstrated that DR may retard brain aging by increasing the intracortical inhibition effect and improve the function of visual cortical neurons in visual information processing.This DR-induced elevation of cortical inhibition may favor the brain in modulating energy consumption based on food availability.