Results

Biochemical measurements
HFD fed rats showed significant increase in body weight as compared to NPD fed rats (Table 2). In addition, the rats fed HFD showed significant elevation in the basal plasma glucose, triglyceride, total cholesterol and insulin levels at the end of four weeks of dietary manipulation as compared to NPD fed control groups (Table 2). The HFD fed rats exhibited significant elevation in basal fasting glucose and showed significant impairment in glucose tolerance to exogenously administered glucose (Fig 1). Estimation of AUC values indicated 28.4 % increase in plasma glucose of HFD fed when compared to NPD fed rats.
Table 2  Various parameters of NPD and HFD fed rats
Parameter   NPD fed   HFD fed
Body weight (gm)  259.2 ± 5.3  315.0 ± 6.5***
plasma glucose (mg/dl)  87.5 ± 2.5  111.0 ± 0.9***
Plasma triglycerides (mg/dl)  41.3 ± 1.7  89.7 ± 7.2***
Plasma cholesterol (mg/dl)  48.9 ± 3.7  87.5 ± 2.6***
Plasma Insulin (ng/ml)  1.90 ± 0.15  3.05 ± 0.21*
pD2 of 5-HT  5.74 ± 0.09  6.00 ± 0.06
Emax of 5-HT  30.0 ± 1.8  49.0 ± 2.0**
pD2 of Ang II  7.69 ± 0.08  7.31 ± 0.18
Emax of Ang II  25.0 ± 3.4  34.0 ± 3.0*
Each point is represented as mean ± SEM *p < 0.05, **p < 0.01 and ***p < 0.001 Vs NPD fed group
Figure 1  Effect of HFD on intra peritoneal glucose tolerance test (IPGTT) in rats, as compared to NPD fed group. All values are expressed as mean ± SEM (n = 8) *p < 0.05, **p < 0.01, ***p < 0.001 Vs NPD fed group

Vascular Responses
Cumulative concentration response curves of 5-HT and Ang II for both HFD fed rat thoracic aortae showed an increase in Emax (Fig 2 and 3) with out any change in pD2 values when compared to NPD fed rats (Table 2). There was no significant change in both Emax and pD2 values with KCl in both groups (data not shown). The order of potency of agonists in both groups was Ang II>5-HT>KCl.
Figure 2  Cumulative concentration response curve to 5-HT in helically cut aortic strip preparations obtained from NPD fed and HFD fed rats. Each point is represented as mean ± SEM (n = 5) *p < 0.05, **p < 0.01 Vs NPD fed group
Figure 3  Cumulative concentration response curve to Ang II in helically cut aortic strip preparations obtained from NPD fed and HFD fed rats. Each point is represented as mean ± SEM (n = 5) *p < 0.05, **p < 0.01 Vs NPD fed group