The Changes On The Expression Of TGF-β₁ And PDGF-B In Central Nervous System Following Spinal Cord Hemisection In The Adult Rhesus

Objective: To investigate the distribution and changes of TGF- β₁ and PDGF-B in the central nervous system of the adult rhesus following spinal cord hemisection. Method: 15 adult rhesus were divided into five groups randomly. Spinal cord hemisection were performed at T₁1 level in rhesus, while control group did not receive half-transection of the spinal cord . Hindlimb function was evaluated and cortical somatosensary evoked potentials(CSEP) were recorded after operation.The aminals received spinal cord hemisection were allowed to survive for 7 days, 14days, 30days and 90days. The caudal and rostral 1 cm spinal cord around the injury site were obtained, and 20 |im thick frozen sections were cut. By the immunohistochemical SP method, we observed the distribution of TGF- β₁ and PDGF-B immunoreactive cells in the ventral horn of the spinal cord and count those immunoreactive cells under microscope. The data were statistically analysed with factorial ANOVA and LSD test. Result: The TGF-β₁ and PDGF-B immunopositive neurons were observed in many areas in CNS. TGF- β₁ immunoreactivity can be seen in the cytoplasm and processes of medulla oblongata lateral reticular nuclear , cerebellar dentate nucleus and inferior olivary nucleus neuron. PDGF-B immunopositive neurons were observed in pontine nucleus of trigeminal, ambiguous nucleus , trigeminal dorsal nucleus, reticular formation. TGF-β₁ and PDGF-B immunoreactivity mainly distributed in ventral horn neurons , nucleus thoracicus and glia cells in white matter of all normal control and hemisection rhesus. Distinct handicap of locomotor function in hindlimbs was observed in half-transaction group as soon as SCI. As time going on , locomotor function improved partially. Partial recovery of hindlimb function in adult monkey compared with that of 24 hours postoperatively was seen from 14 days to 3month inhalf-transection group after SCI. Respectively, the total number of TGF- 3 i and PDGF-B immunoreactive neurons in the ipsilateral and contralateral of spinal cord hemisection site 7 days post operation (dpo) and 14dpo on the operative side had declined to the bottom and had significant difference compared with that of normal control group (P<0.05). As the post-operation time gone, the ventral neuron number returned to normal level in 90days post operation. However, there was no statistic difference between the caudal and rostral spinal cord of all rhesus on the operative side (P>0.05). In addition, TGF- 3 i and PDGF-B had the similar expressional trend after the injury.Conclusion: A reproducible model of SCI in the nonhuman primate was established. Spontaneous partial recovery of the ipsilateral hindlimb function occurred in monkey of spinal cord hemisected during different periods. It was indicated that there was functional plasticity in the spinal cord after hemisection injury . TGF- 3 i and PDGF-B had the similar expressional trend, the immunoreactive positive neurons in ventral horn following spinal cord hemisection reached the most declined level in 7 dpo, 14dpo, and returned to normal level in 90dpo, which showed that TGF- 3 i and PDGF-B might involved in the secondary injury and function restoretive process after spinal cord injury.