Dw. Rickman, Parvalbumin immunoreactivity is enhanced by brain-derived neurotrophic factor in organotypic cultures of rat retina, J NEUROBIOL, 41(3), 1999, pp. 376-384
The rodent retina undergoes considerable postnatal neurogenesis and phenoty
pe differentiation, and it is likely that diffusible neurotrophic factors c
ontribute to this development and to the subsequent formation of functional
retinal circuitry. Accordingly, perturbation of specific neurotrophin liga
nd-receptor interactions has provided valuable information as to the fundam
ental processes underlying this development. Tn the present studies we have
built upon our previous observation that suppression of expression of trk(
B), the high-affinity receptor for brain-derived neurotrophic factor (BDNF)
, in the postnatal rat retina results in the alteration of a specific inter
neuron in the rod pathway-the parvalbumin (PV)-immunoreactive AII amacrine
cell. Here, we isolated retinas from newborn rats and maintained them in or
ganotypic culture for up to 14 days (approximating the time of eye opening,
in vivo) in the presence of individual neurotrophins [BDNF or nerve growth
factor (NGF)]. We then examined histological sections of cultures for PV i
mmunoreactivity, In control cultures, only sparse PV-immunostained cells we
re observed. In cultures supplemented with NGF, numerous lightly immunostai
ned somata were present in the inner nuclear layer (INL) at the border of t
he inner plexiform layer (IPL). Many of these cells had rudimentary dendrit
ic arborizations in the IPL. Cultures supplemented with BDNF displayed nume
rous well-immunostained somata at the INL/IPL border that gave rise to elab
orate dendritic arborizations that approximated the morphology of mature AI
I amacrine cells in vivo. These observations indicate that neurotrophins ha
ve specific effects upon the neurochemical and, perhaps, morphological diff
erentiation of an important interneuron in a specific functional retinal ci
rcuit. (C) 1999 John Wiley & Sons, Inc.