CEFYBO   02669
CENTRO DE ESTUDIOS FARMACOLOGICOS Y BOTANICOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Clock gene expression and cellular localization in the golden hamster retina
Autor/es:
DE ZAVALÍA N; FERNANDEZ DIEGO C; SANDE PH; CHIANELLI MONICA; ALDANA MARCOS HERNÁN; GOLOMBEK DIEGO A; ROSENSTEIN RUTH E
Lugar:
Buzios, Brasil
Reunión:
Congreso; I Congreso IBRO/LARC de Neurociencias para Latinoamérica, Caribe y Península Ibérica; 2008
Institución organizadora:
IBRO/LARC
Resumen:
The mammalian retina contains single or multiple intrinsic circadian oscillators that can be
entrained by light cycles. The aim of the present work was to investigate circadian variations of two
clock-gene proteins (BMAL1 and CLOCK), their localization, and the influence of the suprachiasmatic
nuclei (SCN) on these rhythms. Methods: Male Golden hamsters were kept under a photoperiod of 14h
of light-10h of darkness (LD), with free access to food and water. In some experiments, animals were
kept in constant darkness (DD) for 48h. In one group of animals, bilateral thermic lesions of the SCN
were performed. After surgery, SCN-lesioned animals were exposed to a light-dark cycle for 15 days, and
then transferred to constant darkness for 24h. BMAL1 and CLOCK levels were assessed by Western
blotting of nuclear and cytosolic fractions from hamster retinas excised at midday, midnight, subjective
midday or subjective midnight. BMAL1 and CLOCK localization was examined by
immunohistochemistry. Results: Nuclear levels of BMAL1 and CLOCK were significantly higher at
midday (BMAL1: 19897±181, CLOCK: 514±89) than at midnight (BMAL1: 13410±205, CLOCK:
171±41) (p<0.01), while in the cytosolic fraction no changes were observed. A similar profile was
observed in animals kept in constant darkness (BMAL1: 12h, 16833±344; 24h, 9246±1068. CLOCK:
12h, 371±64; 24h, 91±53) as well as in SCN-lesioned animals (BMAL1: 12h, 17455±371; 24h,
9571±566. CLOCK: 12h. 405±53; 24h, 113±47). In both cases, nuclear levels of these proteins were
significantly higher at subjective midday than at subjective midnight (p<0.01). BMAL1 and CLOCK
were localized in ganglion cell layer. Conclusions: These results indicate significant circadian variations
of BMAL1 and CLOCK nuclear levels in the hamster retina, which are regulated by a local circadian
clock, presumably located in retinal ganglion cells.