Effects of hyperbaric oxygen on the expression of inflammosome NALP3 in the rats after spinal cord injury

Abstract

Objective To investigate the effects of hyperbaric oxygen (HBO) on the expression of inflammosome NALP3 in rats after spinal cord injury, so as to lay a good foundation for the research on the mechanism involved in the treatment and recovery of spinal cord injury(SCI). Methods One hundred and twenty SD rats, with a body weight from 250 g to 300 g were divided into 4 groups: the sham surgery group (or the control group), the spinal cord injury group(or the SCI group), the SCI+ HBO group, the sham surgery + HBO group. In the control group, the vertebral lamina in T10 was surgically opened, with the spinal cord exposed, but without SCI. In the SCI group, injury of T10 section was inflicted with a force of 25 gcm. For the SCI+ HBO group, the animals received HBO therapy following development of the SCI model. In the sham surgery + HBO group, the animals also received HBO therapy. The animals of the 4 groups were sacrificed respectively at h 12, d 1, d 3, d 7 and d 14, and the tissues in the injured sections of the spinal cord were collected to detect the expression of inflammosome NALP3. Results RT-PCR detection indicated that the values of NALP3, ASC and caspase-1 were decreased significantly at d 3 and d 7, as compared with those of the SCI group (P<0.05). The expression of NALP3 mRNA in the spinal cord of the SCI+ HBO group [1 d: 1.26±0.17, 3 d: 1.14±0.02, 7 d: 1.12±0.12] was significantly lower than that of the SCI group [1 d: 1.54±0.05, 3 d: 1.48±0.14, 7 d: 1.45±0.15], with statistical significance (P<0.05). Detection by Western-Blot demonstrated that the grey values of NALP3 at d1, d 3 and d 7 in the SCI + HBO group were significantly decreased, when compared with those of the SCI group, and the grey values of ASC and caspase-1 at d 3 and d 7 were also significantly decreased, when compared with those of the SCI group (P<0.05). The expression of NALP3 in the spinal cord of the SCI+ HBO group [1 d: 0.51±0.01, 3 d: 0.44±0.06, 7 d: 0.42±0.07] was significantly lower than that of the SCI group [1 d: 0.58±0.02, 3 d: 0.55±0.08, 7 d: 0.50±0.03], also with statistical significance (P<0.05). Conclusions HBO could compromise the mRNA expressions of NALP3, ASC and caspase-1 in the damaged spinal cord tissue rats. Secondary damage to the spinal cord could be alleviated through the inactivation of NALP3 inflammosome by HBO. At the same time, HBO could protect the remaining peripheral neural cells in the injured spinal cord tissue and promote neural recovery after SCI. Key words: Animal model; Spinal cord injury; NALP inflammosome; Hyperbaric oxygen; Rats