Objective      To study the relationship between the hypothalamic expression of cannabinoid receptor type Ⅰ and food intake during hypoxia exposure in rats.       Methods      Adult SD rats were randomly divided into 3 groups: normal group (N)

2day hypoxia exposure group (H1d) and 7day hypoxia exposure group (H7d). The rats of the hypoxia groups were put into a hypobaric chamber simulating 5 000meter high altitude for 1 or 7 d

and the food intake and body weight of each group were recorded. The expression levels of CB1 and c Fos in the hypothalamus were detected by Western blotting and immuohistochemical assay.     Results        After exposure to hypoxia

the food intake of the H1d group was lower than that of the N group significantly (4.9±0.7 vs15.5±2.7 g

P0.05). The level of CB1 in the arcuate nucleus (ARC)

later hypothalamic area (LH) and ventromedial hypothalamic nucleus (VMH) was reduced obviously

and the expression of cFos in the ARC

LH and VMH was decreased

too. The food    intake was increased along with the days of exposure to hypoxia

and in 3~7 d after hypoxia exposure

the rats in the H7d group had the food intake similar with the N group. The levels of CB1 and c-Fos had no significant changes between the H7d group and the N group.    Conclusion       The down regulation of CB1 and c-Fos in the ARC

LH and VMH may be closely associated with the food intake decrease induced by acute exposure to hypoxia.