AN ASPECT OF DIFFERENTIAL TANYCYTIC AND METABOLIC RESPONSES TO HIGH-FAT AND HIGH-FRUCTOSE DIETS IN THE MEDIAN EMINENCE OF MALE RATS

The effects of chronic high-fat diet (HFD) and high-fructose water (HFW) consumption on glial activation and metabolic signaling in the median eminence (ME) were investigated using immunohistochemical analysis. Adult rats were assigned to control (C), HFD, and HFW groups. Prior to sacrifice, blood samples were collected for the assessment of serum triglyceride, total cholesterol, HDL, and LDL levels, confirming the establishment of a metabolic syndrome profile in the experimental groups. GFAP, leptin receptor (LepR), insulin receptor (IR), glucose transporter-1 (GLUT1), cocaine- and amphetamine-regulated transcript (CART), and Nestin immunoreactivity were evaluated in the ME. Quantitative image analysis was performed using Fiji (ImageJ), and statistical analyses were conducted using GraphPad Prism. GFAP immunoreactivity increased in both experimental groups, with the highest glial activation observed in the HFW group; LepR and IR expression were most prominent in the HFD group; GLUT1 immunoreactivity was enhanced in the HFW group and reduced in the HFD group; CART expression was highest in the HFD group and decreased in the HFW group; and Nestin expression showed a progressive increase from control to HFD and HFW groups, with all intergroup differences reaching statistical significance (p < 0.05). These findings demonstrate that both dietary interventions induce metabolic syndrome–associated alterations in glial activation and tanycytic plasticity within the median eminence, with fructose intake producing more pronounced glial and structural changes, while high-fat feeding predominantly enhances leptin–insulin signaling.