Altered Monoamine Metabolism in High Fat Diet Induced Neuropsychiatric Changes in Rats

Abstract

Objective: To investigate the role of central and peripheral monoamine metabolism on neuropsychological status in high fat diet induced obese rats. Method: Animals were fed on high fat diet for 12 weeks. Periodically blood was collected to estimate serum Metanephrine (MN) levels. After 11 weeks, behavioural paradigms of depression, locomotor activity and cognition were performed. Central (brain) and peripheral i.e. Visceral White Adipose Tissue (vWAT) and Brown Adipose Tissue (BAT) MN levels, Monoamine Oxidase A and B (MAO-A, MAO-B) enzyme activity and Acetylcholinesterase (AChE) activity was estimated. Results: High fat diet significantly increased the body weight which was negatively correlated with the serum metanephrine concentration. However, metanephrine concentration in brain was significantly decreased whereas it significantly increased in vWAT with no change in BAT. In obese animals, immobility time in forced swim test and transfer latency in elevated plus maze was significantly increased while locomotor activity was significantly decreased. Central MAO-A and MAO-B activities were increased while enzyme activities showed a significant reduction in vWAT with no change in BAT. Brain AChE activity was also increased significantly in obese rats. Conclusion: Metabolism of biogenic monoamines plays a critical role in altered neuropsychiatric behaviours associated with diet induced obesity.