Protective effect of teprenone on neurobehavioral damage in rats with subchronic benzoapyrene exposure

Background Benzoapyrene (BaP) is neurotoxic and can cause neurobehavioral abnormalities in exposed humans and animals. Teprenone has neuroprotective effects, but whether it can prevent or antagonize BaP-induced neurotoxicity remains unclear.

Objective This experiment observes the effect of teprenone on the learning and memory ability of subchronically BaP exposed rats, and explores the protective effect of teprenone on BaPinduced neurobehavioral damage, aiming to provide a basis for the prevention and control of BaP neurotoxic effects.

Methods Forty healthy male SD rats weighing 180-200 g were randomly divided into a solvent (olive oil) control group, a teprenone group, a BaP group, and a teprenone+BaP group, with 10 rats in each group. Every other day, teprenone was intragastrically administered at a dose of 800 mg·kg^-1 (by body weight), and BaP at 6.25 mg·kg^-1 was given by intraperitoneal injection, for 90 d in total. The neurobehavior was tested by the Morris water maze. After paraffin sectioning and HE staining, the histopathological changes of hippocampus were observed. The apoptosis rate of hippocampal nerve cells was determined by TUNEL and Annexin V-FITC/PI double staining. The expression level of heat shock protein 70 (Hsp70) was detected by Western blotting.

Results The weight gain of the teprenone+BaP group(311.10±22.38) g was greater than that of the BaP group(283.42±33.95) g (P < 0.05). The Morris water maze results showed that the average escape latency(29.17±1.90) s and the average total distance(132.51±1.96) cm of the teprenone+BaP group were lower than that of the BaP group(46.77±2.14) s and (181.97±2.09) cm (P < 0.05) respectively. The BaP group showed nerve cell destruction, loss of neurons, and disorderly arrangement in hippocampus; in contrast, the above damage of the teprenone+BaP group was much alleviated than that of the BaP group. The apoptosis rate of hippocampal neurons of the teprenone+BaP group(7.73±5.16)% was lower than that of the BaP group(53.10±7.34)%, and the expression level of Hsp70 protein of the teprenone+BaP group (0.89±0.09) was higher than that of the BaP group (0.49±0.10) (P < 0.05).

Conclusion Teprenone can ameliorate the neurobehavioral damage of rats induced by BaP exposure, which may be related to its function of decreasing neuronal apoptosis.