Effect of fasting and refeeding on the activities of monoamine oxidase andantioxidant enzymes in rat hypothalamus and brown adipose tissue

Fasting for 48 h and the same period of recovery induced by 48 h refeeding increased rat hypothalamic monoamine oxidase (MAO) activity. However, in th e interscapular brown adipose tissue (IBAT), only refeeding induced a signi ficant elevation of the enzyme activity. As far as hypothalamic antioxidati ve enzymes are concerned, the copper zinc superoxide dismutase (CuZnSOD) ac tivity was decreased in refed rats only. However, in the IBAT both food dep rivation and refeeding induced a significant decrease in catalase (CAT) act ivity. Under the influence of fasting the adrenal glands were strongly acti vated as judged by the increased dopamine-beta-hydroxylase (DBH) activity a nd decreased cholesterol concentration. Refeeding brought both parameters t o control levels indicating full recovery of these glands. As expected, fas ting for 48 h induced a significant decrease in serum glucose but an increa se in FFA concentrations. Thus, it can be concluded that both fasting and r efeeding resulted in increased activation of hypothalamic MAO, whereas CuZn SOD activity was decreased only by refeeding. However, in the IBAT only ref eeding increased MAO activity whereas both fasting and refeeding decreased that of CAT. In conclusion, it may be assumed that food deprivation for 48 h and the same duration of refeeding influenced MAO and antioxidative enzym es activities in the rat hypothalamus and IBAT in a tissue specific manner.