Effects of neurotrophins on cortical plasticity: same or different?
Neurotrophins are important regulators of visual cortical plasticity. It is still unclear, however, whether they play similar or different roles and which are their effects on the electrical activity of cortical neurons in vivo. We therefore compared the effects of all neurotrophins, nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-4 (NT-4), and neurotrophin-3 (NT-3) on visual cortical plasticity and on cell spontaneous and visually evoked activity. Rats were monocularly deprived for 1 week at the peak of the critical period, and neurotrophins were infused intracortically. The main finding is that, with the exception of NT-3, all neurotrophins affect the outcome of monocular deprivation, but there are clear differences in their mechanisms of action. In particular, NT-4 and NGF counteract monocular deprivation effects without causing detectable alterations either in spontaneous or visually evoked neuronal activity. BDNF is less effective on ocular dominance plasticity and, in addition, strongly affects spontaneous and visually evoked activity in cortical neurons.
Lodovichi
C
C
Scuola di Studi Superiori Sant'Anna, 56126 Pisa, Italy. lodovica@in.pi.cnr.it
Berardi
N
N
Pizzorusso
T
T
Maffei
L
L
D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology; D004553:Electric Conductivity; D005074:Evoked Potentials, Visual / Q000187:drug effects / Q000502:physiology; D005556:Form Perception / Q000187:drug effects / Q000502:physiology; D020932:Nerve Growth Factor / Q000494:pharmacology; D009414:Nerve Growth Factors / Q000494:pharmacology*; D009473:Neuronal Plasticity / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D018696:Neuroprotective Agents / Q000494:pharmacology; D020933:Neurotrophin 3 / Q000494:pharmacology; D051381:Rats; D020318:Rats, Long-Evans; D009435:Synaptic Transmission / Q000187:drug effects; D015349:Vision, Monocular; D014793:Visual Cortex / Q000166:cytology* / Q000187:drug effects*; D014794:Visual Fields / Q000187:drug effects / Q000502:physiology; D014795:Visual Pathways
D019208:Brain-Derived Neurotrophic Factor; D009414:Nerve Growth Factors; D018696:Neuroprotective Agents; D020933:Neurotrophin 3; D020932:Nerve Growth Factor; C073922:neurotrophin 4