AIM:To explore the influence and significance of early monocular deprivation on the expression of brain derived neurotrophic factor(BDNF)and TrkB receptor in rats' retina.

METHODS: Totally 40 neonatal rats were randomly allocated into 6 groups: normal group of postpartum 28 days(NorP28), normal group of postpartum 35 days(NorP35), normal group of postpartum 42 days(NorP42), monocular deprivation group of postpartum 28 days(MDP28), monocular deprivation group of postpartum 35 days(MDP35)and monocular deprivation group of postpartum 42 days(MDP42). For the MD model, we sutured together the right eyelids of rats at postpartum 21 days. A subset of rats at each time points were killed, then the retinas were removed and frozen for detecting the expression pattern of BDNF and its receptor TrkB by means of Western blot and immunohistochemistry.

RESULTS: During the visual development critical period, the expression of BDNF and TrkB receptor had no significant change with the growth of age. After the early monocular deprivation, BDNF and TrkB receptor were significantly increased its expression at postpartum 28 days, then decreased at postpartum 35 days and maintained a steady level between postpartum 35 days to postpartum 42 days. BDNF expressed in ganglion cell layer, inner nuclear layer and outer nuclear layer of retina, while TrkB receptor expressed only in ganglion cell layer. In response to MD, the expression of BDNF and TrkB receptor positive cells was dramatically up-regulated in ganglion cell layer at postpartum 28 days, and then decreased gradually at postpartum 35 days to postpartum 42 days.

CONCLUSION: The expression of BDNF and its TrkB receptor presents a visual-experience dependency, and they participate in the onset of monocular deprivation amblyopia.