Changes in platelet-activating factor receptor binding characteristics in cerebral thrombotic core and penumbra of tree shrews

AIM: To observe the changes in platelet-activating factor (PAF) receptor binding characteristics and explore the action of PAF on formation of thrombotic core and penumbra following local cerebral ischemia. METHODS: Neuron's membrane protein was abstracted, and the local cerebral ischemia model were induced by photochemistry in tree shrews. The PAF binding sites on central neuron membrane were studied by-PAF binding assay. RESULTS: There were two different affinities of PAF receptors on tree shrew's brain cell membrane, with kD₁=(3.61 ±0.72) nmol/L and kD₂=(17.04±2.41) nmol/L, corresponding respectively to maximum number of binding sites: B_max1=(1 457.94±168.01) pmol/g protein and B_max2=(5 017.40±742.16) pmol/g protein. The binding sites decreased in ischemic core, penumbra and contralateral regions at 4,24 and 72 h after ischemia (P<0.01), with those of 24 h reaching the minimum levels. CONCLUSION: PAF receptors play an important role in cerebral ischemia, may be related to the secondary damage in ischemic penumbra, and also are molecular bases of brain injury induced by PAF.