Objective: To observe the effects of acupuncture at different time-windows on hypoxic-ischemic cerebral palsy rats

and to study its underlying neurobiochemical mechanism. Methods: Eighty-five neonatal SD rats were randomized into control group (n=16)

model group (n=23)

acupuncture group-1 (n=23

acupuncture was given beginning 24 h after operation) and acupuncture group-2 (n=23

acupuncture was given beginning 8 days after operation). Cerebral palsy model was established by occlusion of the left common carotid artery and inhalation of 8% oxygen plus 92% nitrogen. “Baihui"(GV 20)

Tempale-Point-1 (0.8 cm superior to the external auditory canal aperture)

“Quchi"(LI 11)

“Neiguan"(PC 6)

“Zusanli"(ST 36) and “Yongquan"(KI 1) were punctured and the former two acupoints were stimulated electrically with an electroacupuncture apparatus. The death rate

forepaw-touching test (adhesive plaster tearing-off test)

brain weight

neuronal number of hippocampal CA1 region were measured and the expression of nerve growth factor (NGF) in the brain was assayed with immunohistochemical method. Results: The death rates (13.0% and 21.7%) of both acupuncture group-1 and -2 were significantly lower than that (34.8%) of model group (P< 0.05). The duration values for tearing off adhesive-plaster on 7 d

14 d and 21 d of acupuncture group-1 and on 14 d of acupuncture group-2 were markedly shorter than that of model group (P< 0.05)

suggesting functional improvement of the rats' forelimbs. No significant difference was found among the 4 groups in the left brain weight (P<0.001). The number of neurons of hippocampal CA1 region on the left side was biggest in control group

bigger in acupuncture group-1

smaller in acupuncture group-2 and smallest in model group respectively. Twenty-one days after operation

the number of NGF immunoreaction (IR) strongly-positive neurons in the cerebral cortex

straiate body and hippocampus was biggest in acupuncture group-1

bigger in acupuncture group-2 and smaller in model group

and only very weakly IR-positive neurons were found in control group. Conclusion: ① Acupuncture can upregulate the long-term expression of NGF in the brain

which may contribute to the effect of acupuncture in improving cerebral palsy. ② Acupuncture therapy may be used to treat cerebral palsy at the early stage and can reduce hypoxia-ischemia induced injury of cerebral neurons.