Spinal cord transection induce aromatic L-amino acid decarboxylase cells to produce 5-HT

English Keywords:Spinal cord injury  Aromatic amino acid decarboxylase  5-hydroxytryptamine

English Abstract:

  【Abstract】 Objectives: To reveal the role of aromatic L-amino acid decarboxylase cells(AADC) after spinal cord injury(SCI) by investigating the AADC distribution in spinal cord and the 5-HT expression in AADC following SCI at different postoperative intervals. Methods: Sixty adult male Wistar rats were randomly divided into normal control group(12 rats), spinal cord injury 2 days group(24 rats, sham in 12 rats), and spinal cord injury 60 days group(24 rats, sham in 12 rats). By using negative pressure suction device, T10-11 spinal cord was completely separated from 1-3mm, and the spinal cord complete transection model at T10-11 level was established. The BBB score of different time points was used to evaluate the hindlimb motor function in SCI rats. Each group was perfused and drawed at each time point and the 5-HTP(100 mg/kg) was intraperitoneally injected 30min before perfusion. Immunofluorescence technology was used to detect the expression of AADC and 5-HT in lumbar(L segment) and sacrocaudal segments(S+C segment) of spinal cord. Results: The BBB score of SCI rats was 0, 1.00±0.58, 3.30±0.95, 6.30±0.10, 7.50±0.36 and 7.87±0.08 at 1-2, 3, 7, 14, 28 and 60 days respectively. AADC cells were mainly expressed in the dorsal horn of spinal cord, intermediate zone, and around the central canal. In control group, SCI 2d group and SCI 60d group, the number of AADC in L segment was 46.75±5.50, 49.50±4.87 and 48.50±6.38 cells respectively; it was 1026.50±66.59, 1066.75±80.56 and 1046.25±67.79 cells in S+C segment respectively. There was no significant difference between the three groups(P>0.05). The expression of 5-HT was not seen in the AADC cells in the L segment and S+C segment of the normal control group. But 5-HT expression was observed in the AADC cells in SCI 2d and 60d group, which was (44.43±6.03)% and (96.20±1.53)% in L segment, (44.45±5.71)% and (95.14±3.02)% in S+C segment. There was significant difference between the two groups(P＜0.05). Conclusions: There is no significant difference in SCI and normal rats respect to AADC cells distribution and numbers. Following complete transection of the rat spinal cord at T10-11 level, the function of AADC cells in the spinal cord distal to the lesion was increased, and exogenous 5-HTP can be used to generate 5-HT.