INIMEC - CONICET   05467
INSTITUTO DE INVESTIGACION MEDICA MERCEDES Y MARTIN FERREYRA
Unidad Ejecutora - UE
artículos
Título:
BETA-ENDORPHIN INVOLVEMENT IN THE REGULATORY RESPONSE TO BODY SODIUM OVERLOAD.
Autor/es:
CAEIRO X., HANSEN C., GARCÍA N., VIVAS L.
Revista:
NEUROSCIENCE
Referencias:
Año: 2006 vol. 142 p. 557 - 565
ISSN:
0306-4522
Resumen:
The present study was performed to examine the role of the endogenous ©¬-endorphinergic system on blood pressure regulation, sympathetic and brain activity during body sodium overload. ©¬-Endorphin knockout (©¬end-/-), heterozygous (©¬end+/-) and wild-type (©¬end+/+) mice were submitted for two weeks to either a normal or a high sodium diet (NSD and HSD respectively), and systolic blood pressure (SBP), urinary catecholamines (as an index of sympathetic nervous system activity), and the brain pattern of Fos-like immunoreactivity (as a marker of neuronal activation) were evaluated in each group.  HSD caused a significant increase in SBP in ©¬end-/- mutant mice compared with ¥âend+/+ mice kept in the same experimental conditions (P<0.01), but no statistical differences were observed between ©¬end+/- and ©¬end+/+ on a HSD. Moreover, when animals from the three genetic lines were fed with a NSD no changes in SBP were evidenced. With regard to brain activity, ©¬end-/- mice maintained on a HSD showed a significant increase in Fos-like immunoreactive neurons in the median preoptic nucleus (p<0.01) compared to ©¬end+/- and ©¬end+/+ animals. Additionally, ¥âend-/- mice had higher levels of urinary epinephrine excretion (p<0.05 ) on a HSD in comparison to ©¬end+/+ and ©¬end+/- animals in the same experimental conditions. No differences, however, were registered in norepinephrine and dopamine urinary excretion in animals from the three genetic lines after two weeks on either a HSD or a NSD. In summary, our results indicate that the ©¬-endorphinergic system may play a part in the compensatory response to sodium overload, since the absence of ©¬-endorphin causes an increase in systolic blood pressure, and increases median preoptic nucleus neural activity and urinary epinephrine excretion. Key Words: ©¬-endorphin knockout mice, systolic blood pressure, catecholamines, sympathetic activity, neuronal activity, median preoptic nucleus.