Effect of Carbachol on brain damage and inflammation of neonatal rats after hypoxia-ischemia

Abstract

Objective To study the effects of Carbachol on brain damage and inflammation after hypoxia-ischemia(HI) in neonatal rats. Methods Sixty of 7-day Wistar rats were randomly divided into 3 groups: intervention group, control group and sham operation group, with 20 rats per group.According to the Rice method, 40 HI models (i.e.intervention and control group) were established, and in the sham operation group, rats had an operation that only dissociated the left common carotid artery instead of HI.In the intervention group, the rats received a subcutaneous injection of Carbachol (0.12 mg/kg)after HI, 24 h and 48 h after HI.Meanwhile, the rats of control group received an equivalent volume of saline for 3 times.The rats were killed on day 1 and day 7 after injection and brain was checked damage were evaluated through HE staining and the number of microglias in 3 regions of brain was checked through immunohistochemistry. Results (1) HE staining: the brain issues were normal in appearance and there was not any pathological changes in sham operation group.The brains were damaged both in intervention group (the first day: 94.40±2.22, the seventh day: 91.10±2.51)and control group(the first day: 79.60±3.31, the seventh day: 74.40±5.98), and the damage degree was more serious in control group (all P<0.01). (2)Microglial accumulation: there was no microglial accumulation in sham operation group, but it was evident in the intervention group and control group(P<0.05). In the control group, microglial accumulation in the cortex was persistent from day 1 to 7(the first day: 280.40±3.06, the seventh day: 292.40±10.01, P<0.05), conversely, the number of microglia was attenuated in the hippocampus and white matter on day 7 (P<0.05). The number of microglia was significantly less in intervention group than that in the control group on day 1 and 7, and the difference was statistically significant(P<0.05). Conclusions The brain da-mage of rats caused by HI could induce the activation of microglia; Carbachol could protect the neonatal rats with HI brain damage by reducing the inflammation. Key words: Hypoxia-ischemia; Carbachol; Inflammation; Microglia