Enriched environment and VEGF induced neuroprotection during the critical period of rat visual cortex

ORTUZAR N., ARGANDOÑA E. G., BENGOEXTEA H., BULNES S. , GARCIA S., LEDEZMA R., LEIS O. & LAFUENTE J. V.

Ginebra. Suiza.

Congreso; 6th FENS (Forum of European Neuroscience); 2008

The Federation of European Neuroscience Societies

Postnatal development of the visual cortex is modulated by experience mainly during the critical period. Thereafter, physiological apoptosis occurs when non-functioning neurons die. VEGF is the major angiogenic factor and also has strong neuroprotective and neurotrophic properties in pathological conditions. The same effects have been described for rats reared in an enriched environment. The aim of the present study was to investigate the effects on neuronal and apoptotic densities of the combination of enriched environment (EE) and infusion of VEGF in the visual cortex during the first days of the critical period. VEGF was administered for one week using intracerebral osmotic minipumps placed in middle cortical layers of P18 Long Evans rats. The following groups were used: a) Rats raised in standard conditions (SC) until minipump infusion and in EE after infusion; b) EE-raised rats until minipump infusion and SC afterwards; c) SC raised controls. Neuronal density (ND) and apoptotic density (AD) were measured by the optical dissector method on NeuN and Caspase-3 immunohistochemistry respectively. Infusion-produced lesion induces a delay in the maturation of the visual cortex, which in physiological conditions courses with a decrease in the ND. VEGF prevents pathological neuronal death and probably physiological death as well, as a reduction in AD was found. The combined effect of EE was only achieved when applied after the infusion. All results also appear on the contralateral cortex. We can conclude that combined VEGF infusion and post-surgical EE not only rescue the visual cortex from the effects of lesions, but also rescue cells from physiological apoptosis. Financially supported by by 9/212.327-15887 (Univ. of the Basque Country) SAIOTEK (D. Industry. Basque Government), and IT/460/07 (Basque Government). N. O. : is a predoctoral fellow from UBC O. L. : is a predoctoral fellow from Basque Government S. G. . and R. L. are fellows from the NeuralNet alfa Programme (EU).