24-hour rhythm in gene expression of redox pathway enzymes in rat hypothalamus : effect of melatonin treatment

Abstract: The 24-h changes in medial basal hypothalamic (MBH) gene expression of redox pathway enzymes nitric oxide synthase (NOS)-1 and NOS-2, heme oxygenase (HO)-1 and HO-2, Cu/Znand Mn-superoxide dismutases (SOD) and catalase were examined in adult male Wistar rats. Half of the animals received melatonin (ca. 60 μg/day) in the drinking water. After 1 month, rats were killed at six different time intervals, throughout a 24-h cycle. MBH mRNA levels were measured by real-time PCR analysis. In controls NOS-1 mRNA expression did not exhibit 24-h variations while NOS-2 gene expression peaked at the early light phase of cycle. MBH mRNA for both the inducible (HO-1) and constitutive (HO-2) isoforms of HO showed a significant 24 h pattern with a maximum at the middle of the dark phase or at the early light phase, respectively. None of mRNAs encoding Cu/Zn-SOD, Mn-SOD and catalase exhibited significant 24-h variations in rat MBH under control conditions. Chronic melatonin administration in the drinking water decreased significantly mRNAs for NOS-1, NOS-2, HO-1 and HO-2 as well as changed their 24-h profile. Melatonin augmented gene expression of the antioxidant enzymes Cu/Zn-SOD, Mn-SOD or catalase at certain time intervals onl