CRILAR   12590
CENTRO REGIONAL DE INVESTIGACIONES CIENTIFICAS Y TRANSFERENCIA TECNOLOGICA DE LA RIOJA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
MODULATION OF THE CIRCADIAN RHYTHM OF BODY TEMPERATURE BY INTENSE ACTIVITY IN A SUBTERRANEAN RODENT (Ctenomys cf. knighti)
Autor/es:
TACHINARDI P; - TOMOTANI BM; FLÔRES DEFL; BICUDO JEW; VALENTINUZZI VS; ODA GA
Lugar:
Puebla
Reunión:
Congreso; Third World Congress on Chronobiology; 2011
Resumen:
Most mammals show a daily body temperature (Tb) rhythm which is endogenous
and entrained by light/dark (LD) cycles.
Usually, the highest temperatures occur during the same phase of motor
activity, which often may mislead to the conclusion that the Tb rhythm is a mere
consequence of the activity/rest rhythm. Nevertheless, several studies have verified
that both rhythms persist independently of each other. Intense activity may,
however, modulate some parameters of
the Tb rhythm. Quantifying this modulation helps dissecting the exogenous and
endogenous components of the Tb rhythm when the animal is under different
experimental conditions or in its natural habitat. We investigated this issue
in a subterranean rodent, the tuco-tuco (Ctenomys
cf. knighti), found in northwest Argentina. First
we studied their Tb under an LD cycle and verified a daily Tb rhythm with the highest
temperatures occurring during the dark,
synchronously to running-wheel activity. Furthermore, Tb rhythm persisted under
constant darkness (DD), an evidence
of its endogenous nature. Interestingly, we observed a much smaller variability in rhythmic patterns (period, phase and
amplitude) compared to other
subterranean rodents.
In order to study the exogenous components of the Tb rhythm due to
intense activity, its parameters in
the presence and absence of a running-wheel were compared.
To continuously measure temperature and gross motor activity, telemetric
transmitters were implanted intraperitoneally. Three tuco-tucos were kept
individually in cages equipped with running-wheels and exposed to the following
lighting conditions: 1) DD (44 days); 2) LD (12:12, 14 days); 3)
reestablishment of DD (16 days). The wheels were then removed and the exposure
to the lighting conditions repeated. After running-wheel removal, mean gross
motor activity diminished 54-62% in two animals. Free-running period (ranging
from 23.6 to 24.4 hours) and phase relationship with activity rhythm did not
change significantly. The amplitude, in turn, decreased about 0.5oC
in 2 animals. These results will be important for further analysis of experiments
using running-wheels as well as studies of Tb rhythmicity of tuco-tuco?s in
their natural habitat, where they show frequent bouts of intense activity while
digging.