OBJECTIVETo evaluate protective effect of minocycline,a semisynthetic tetracycline derivative on different traumatic brain injuries in rats and mice.

METHODSThe opened brain trauma was induced in rats and the closed head injury and cold brain injury were induced in mice. In 3 brain trauma models, minocycline (45 mg/kg, ip) was administered twice daily for 2 d before the operation, at 30 min before and 1 h after the operation, and once daily for 2 d following the operation (totally 8 doses in 5 d). After the operation, the behavioral alteration was observed daily, lesion area and survival neuron density were measured at the end of the experiments (14 d after the injuries).

RESULTFor rat opened traumatic injury, minocycline promoted the recovery of hindlimb motor activity (inclined board angle), but did not alter other indexes. For mouse closed head traumatic injury, minocycline reduced the neuron loss, but did not improve behavioral dysfunction. For mouse cold injury-induced trauma, minocycline reduced death rate and lesion area, but did not remarkably improve behavior and neuron loss.

CONCLUSIONMinocycline only has an incomplete neuroprotective effect on different brain traumatic injuries in rats and mice.