The Effect of Estrogen Replacement Therapy on Visceral Fat, Serum Glucose, Lipid Profiles and Apelin Level in Ovariectomized Rats

OBJECTIVES: Ovarian hormones have been shown to regulate body weight, intra-abdominal fat accumulation and plasma level of cytokines. The aim of this study was to investigate the effect of estrogen replacement therapy on visceral adipose tissue, plasma level of apelin, lipid profiles, and glucose in ovariectomized (OVX) rats. METHODS: Thirty female Wistar rats were divided into OVX (n = 20) and sham (n = 10) groups. OVX rats were subdivided into estrogen replacement therapy (OVX+est; n = 10) receiving 17 β-estradiol valerates (30 µg/kg, s.c., 5 day/week, for eight weeks), and vehicle control group receiving sesame oil same as experiment group (OVX+ses oil; n = 10). After the treatments, all groups were sacrificed and blood samples were collected, visceral fats were taken from the abdominal cavity and weighed immediately. Apelin were measured using enzyme-linked immunosorbent assay kits. Lipid profiles and glucose were measured using the enzymatic colorimetric method. Data were analyzed with one-way analysis of variance and (P < 0.05) determined as the statistical significance level. RESULTS: After eight weeks, body weight, body mass index (BMI), visceral fat, apelin and lipid profiles (P < 0.01) were increased significantly in OVX rats compared to sham group. Treatment with estrogen leads to significant reduction in body weight and BMI (P < 0.05), there was no significant change in serum apelin level in OVX+est rats compared to OVX+ses. CONCLUSIONS: These results suggest that estradiol replacement therapy successfully attenuated some of the metabolic syndrome components, and apelin does not probably stand as a mediator of these physiological functions.

Dopaminergic activity in the medial prefrontal cortex modulates fear conditioning

The purpose of the present study was to determine the role of medial prefrontal cortex [mPFC] dopaminergic system in fear conditioning response considering individual differences. Animals were initially counterbalanced and classified based on open field test, and then were given a single infusion of the dopamine agonist, amphetamine [AMPH] and antagonist, clozapine [CLZ] into the medial prefrontal cortex. Rats received tone-shock pairing in a classical fear conditioning test and then exposed to the tone alone. Freezing responses were measured as conditioned fear index. The results showed that both AMPH and CLZ infusion in mPFC reduced the expression of conditioned fear. This finding indicates that elevation or reduction in the dopaminergic activity is associated with the decrease of fear responses, despite preexisting individual-typological differences