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Objective: Angiotensin II (Ang II), the main product of renin-angiotensin system (RAS) has a well-known role in cardiovascular regulation. Over-production of Ang II is one of the important underlying mechanisms of hypertension. In this study, the effect of crocin on cardiovascular responses in rats with acute hypertension induced by Ang II was evaluated. Materials and Methods: Rats were divided into six groups (n = 6): 1) Control: rats that received saline, 2) Ang II: rats that received Ang II (300 ng/kg) infused in two min, 3) Losartan (Los) + Ang II : rats that received Los (10 mg/kg, i.v) before Ang II, and 4-6) Crocin (Cro) + Ang II groups: rats that received three doses of crocin (50, 100 and 200 mg/kg, slow i.v) 10 min before Ang II. Femoral artery and vein were cannulated for recording of cardiovascular parameters and injection of drugs, respectively. Systolic blood pressure (SBP), mean arterial blood pressure (MAP) and heart rate (HR) were continuously recorded by power lab system. After injection of reagents and extracts, maximum changes (∆) of MAP, SBP and HR were recorded and compared with control group. Results: Ang II (300 ng/kg) increased maximal changes in MAP, SBP and HR compared to control group (p

In the present study the protective effect of Nigella sativa (N. sativa) on synaptic plasticity impairment induced by lipopolysaccharide (LPS) in rats was investigated. Fifty-eight rats were grouped and treated as follows: 1) control (saline), 2) LPS, 3) LPS-N. sativa, and 4) N. sativa. In a Morris water maze test, the escape latency and traveled path to find the platform as well as time spent and the traveled distance in target quadrant (Q1) were measured. Long term potentiation (LTP) from CA1 area of hippocampus followed by high frequency stimulation to Schafer collateral was studied and slope, slope 10-90% and amplitude of field excitatory field potential (fEPSP) were calculated. The escape latency and traveled path in LPS group were significantly higher than those in the control group while, in LPS-N. sativa group these parameters were significantly lower than those in LPS group. The rats in LPS group spent less time and traveled shorter distance in Q1 than the rats in the control group while, in LPS-N. sativa group the rats spent more time and traveled longer distance than the rats in LPS group. LPS significantly decreased slope, slope 10-90% and amplitude of fEPSP while, in LPS-N. sativa group these parameters increased compared to LPS group. The results indicated that the hydro-alcohol extract of N. sativa protected against synaptic plasticity and spatial learning and memory impairment induced by LPS in rats.