CEFYBO   02669
CENTRO DE ESTUDIOS FARMACOLOGICOS Y BOTANICOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
BEHAVIORAL, HISTOLOGICAL AND BIOCHEMICAL CHANGES INDUCED ON HIPPOCAMPUS AFTER NEONATAL X RADIATION EXPOSURE
Autor/es:
CÁCERES, LG; SARACENO E; AÓN L; ZORRILLA ZUBILETE, M.A; CAPANI, F; GUELMAN, L.R
Lugar:
Washington DC, USA
Reunión:
Congreso; 38th Annual Meeting of the Society for Neuroscience (SFN); 2008
Institución organizadora:
Society for Neuroscience (SFN)
Resumen:
Developing
Central Nervous System (CNS), in particular cerebellum, has been found to be extremely
vulnerable to ROS-mediated, ionizing radiation damage.
The aim of
the present work was to test the radiosensitivity of the hippocampus (Hip), a CNS
region mainly involved in mechanisms of learning and memory.
Neonatal
rats were X-irradiated with 5 Gy in their cephalic ends, up to 48hs of
postnatal life, and were subjected to a passive avoidance test (PA) 30 days after
birth in order to evaluate short and long term hippocampal-related memory. Moreover,
the basal and induced (by NMDA) levels of ROS -main mediators of
radiation-induced damage- as well as the levels of PKC -a protein involved in
the memory mechanism- were determined in the hippocampus and histological and
morphological assessments were also performed.
The
irradiated animals showed a better performance in the PA test compared with
control when tested at short term (rate T2/T1: C= 28.93 ± 6.71; Rx= 51.62 ±
8.22, p< 0.05). while there were no differences between irradiated and
control animals when tested at long term.
The
histology showed no gross changes in the hippocampal. However, an increase in
the number of dendritic spines was observed in Hip of irradiated animals.
The
basal/induced ratio of ROS levels were increased in irradiated animals (C=
0.334 ± 0.016; Rx= 0.450 ± 0.006, p< 0.01), together with PKC levels (pmolPKC/mg
of tissue, C= 39.20 ± 1.70; Rx= 96.97 ± 10.87, p< 0.05)
These data
suggest that increased basal ROS levels found in irradiated animals could trigger
the increase in PKC levels. Likewise, this increase could be responsible for
the improvement in the performance of irradiated animals observed in the PA
test at short term. Even more, stimulated PKC signaling pathway would regulate
dendritic spines density in the Hip.
Taken
together, although no cytoarchitectural damage was induced to Hip, these
results could suggest the existence of hippocampal plastic compensatory mechanism
to counteract ROS attack, and could be proposed that ROS can be considered as small messenger
molecules critical for neuronal signaling.