Neuronal alterations due to focal chemical hypoxia

CALTANA L; MERELLI A; LAZAROWSKI A; RAMOS AJ; BRUSCO A

Pinamar, Argentina

Congreso; 10th Congress of Panamerican Association for Biochemistry and Molecular Biology -20va Reunion de la Sociedad Argentina de Neuroquimica; 2005

PABMB-SAIB-SAN

Neuronal alterations due to focal chemical hypoxia. Caltana L; Merelli A; Lazarowski A; Ramos A; Brusco A. IBCyN. Fac .de Medicina.UBA. lauracaltana@hotmail.com Hypoxia is one of the pathological factors inducing neuronal injury. Cobalt chloride (CoCl2) is a synaptic blocker and activator of the hypoxia-inducible factor-1. Adult male Wistar rats were anaesthesized, placed in a stereotaxic device and intracerebrally injected with 2 ìl of 50 mM CoCl2 in the right hemisphere and with 2 ìl of  saline solution (SS) in left hemisphere. The site of injection was layer 2-3 of fronto-parietal cortex (Bregma –1.30 mm). One group of animals was fixed 6 hours after the surgery and other group 5 days later. The lesion area was studied by electron microscopy and neuronal death was determined by Hoescht 33342 and TUNEL techniques. Larger intercellular spaces and a disruption of neuronal and glial morphology with extended processes forming an irregular network were observed. In the penumbra area abundant images of nuclear cleavage, cytoplasmic multivesicular contents and altered mitochondria ultrastructure (abnormal crests with swelling images). There were abnormal presynaptic structures as well as lamellar images of membranous processes included in the matrix between neurons and glial cells. Outside the penumbra limits and in the SS injection zone, the brain tissue presented the typical morphology.  Abundant TUNEL+ nucleus and with various lobes (stained with Hoescht 33342) indicated cellular death 6 hs after the treatment but not at 5 days. Our results suggest that CoCl2 is able to induce local neuronal and glial alterations in the CoCl2-exposed brain tissue that persist 5 days after the lesion. The localized damage makes this model useful to induce a very focal brain injury. Grant UBACyT M-072.