Expression of GABAB1 receptors in spinal dorsal horn neurons in rats with diabetic neuropathic pain

Objective To investigate the role of GABAB1 receptors in spinal dorsal horn neurons in the development of diabetic neuropathic pain （DNP）. Methods Sixty pathogen free male SD rats aged 4 weeks weighing 150-170 g were randomly divided into 2 groups （ n = 30 each）： control group and DNP group. Diabetes mellitus was induced by single intraperitoneal injection of streptozotocin 50 mg/kg. Blood glucose levels and paw withdrawal threshold to mechanical stimuli were measured at 3, 5 and 7 weeks （T1, T2, T3 ） after IP STZ/NS （ n = 10 each）. The animals were sacrificed after PWL measurement. The lumbar segment of the spinal cord was removed for determination of the expression of GABAB1 receptors by immuno-histochemistry, RT-PCR and Western blot analysis. Results The blood glucose levels were significantly higher while the PWT was significantly lower at T1,T2 and T3 in group DNP than in control group. The expression of GABAB1 receptor mRNA and protein in spinal dorsal horn was significantly lower at T2 and T3 in DNP group than in control group. Conclusion The expression of GABAb1 receptors is down-regulated in spinal dorsal horn neurons in rats with DNP. Key words: Neuralgia;  Diabetes complications;  Spinal cord;  Receptors, GABA-B