Objective    To observe the spontaneous rhythmic contraction of in vi

tro small intestinal smooth muscle and the number and function change of interstitial cells of Cajal (ICCs) in mice after severe head injury (SHI)

and to study the possible mechanism of intestinal motility disturbance (IMD) induced by SHI.     Methods    Thirty-six 6- to 8-week-old clean healthy male Kunming mice with body weight 35±5 g were randomly and evenly divided into an SHI group (which underwent  an operation using the modified Feeney’s method) and a control group (which underwent a sham operation

opening skull but avoiding brain injury). The movement pattern

amplitude

and frequency of in vitro terminal ileum smooth muscle strips

and the number of terminal ileum ICCs were detected at 1

3

and 7 d after SHI.     Results    (1) Compared with the control group

the spontaneous rhythmic contraction amplitude of smooth muscle was significantly reduced at 1 d (0.16±0.04 g vs 0.31±0.05 g)

3 d (0.16±0.04 g vs 0.23±0.06 g)

and 7 d (0.22±0.07 g vs 0.27±0.05 g) after SHI in the SHI group (P0.05). The spontaneous rhythmic contraction frequency of smooth muscle was significantly reduced at 1 d (30.23±3.71 times/min vs 34.55±1.99 times/min) and 7 d (30.34±4.56 times/min vs 33.10±0.81 times/min) after SHI (P0.05)

but not at 3 d (31.46±4.64 times/min vs 33.39±2.17 times/min

P0.05) after SHI. The muscle strip movement pattern became disordered and irregular. (2) Compared with the control group

the cell number of ICCs significantly decreased at 1 d (189±41 cells/mm

2

vs 303±10 cells/mm

2

)

3 d (156±39 cells/mm

2

vs 305±9 cells/mm

2

)

and 7 d (215±28 cells/mm

2

vs 325±42 cells/mm

2

) after SHI in the SHI group (P0.05). The network of ICCs was obviously damaged and became thinner.     Conclusion    Severe damage of ICCs and spontaneous rhythmic contraction disorder of smooth muscle in small intestine emerge after SHI and result in IMD.