Effect of a High-Fat Diet on 24-Hour Pattern in Expression of Prolactin and Redox Pathway Enzymes in the Rat Adenohypophysis

The effect of a high-fat diet (35% fat) on 24-h changes in expression of prolactin and redox pathway enzyme genes was examined in the anterior pituitary of male rats. When body weight of high-fat fed rats attained values about 20- 25 % higher than controls (after 66 days of treatment) animals were sacrificed at 6 different time intervals throughout a 24-h cycle. Anterior pituitary mRNA levels were measured by real-time PCR analysis. In control rats expression of the prolactin gene peaked in anterior pituitary at early scotophase, 3 h in advance to the peak in plasma prolactin levels. In high-fat fed rats this correlation was lost. A disruption of 24-h rhythmicity of pituitary gene expression of heme oxygenase (HO)-2, Cu/Zn- superoxide dismutases (SOD), Mn-SOD, catalase, glutathione peroxidase (GPx) and glutathione reductase (GR) was apparent in high-fat fed rats. Anterior pituitary mRNA levels for nitric oxide synthase (NOS)-2 and HO-2, Cu/Zn- and Mn- SOD and catalase augmented in high-fat fed rats, whereas those of GPx and GR decreased. The results indicate a disrupted coordination between prolactin gene expression and prolactin release in high- fat fed rats that comes along with a disturbed expression of redox enzyme genes in the anterior pituitary.