INVESTIGADORES
PERELLO Mario Carlos
artículos
Título:
Divergent neuronal circuitries underlying acute orexigenic effects of peripheral or central ghrelin: critical role of brain accessibility
Autor/es:
AGUSTINA CABRAL; SPRING VALDIVIA; GIMENA FERNANDEZ; MIRTA REYNALDO; MARIO PERELLO
Revista:
JOURNAL OF NEUROENDOCRINOLOGY.
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Lugar: Londres; Año: 2014 p. 1 - 14
ISSN:
0953-8194
Resumen:
Ghrelin is an octanoylated peptide hormone that potently and rapidly
increases food intake. The orexigenic action of ghrelin involves the
hypothalamic arcuate nucleus (ARC), which is accessible to plasma
ghrelin and expresses high levels of the ghrelin receptor. Local
administration of ghrelin in a variety of other brain nuclei also
increases food intake. It is currently unclear, however, if these
non-ARC ghrelin brain targets are impacted by physiological increases of
plasma ghrelin. Thus, the current study was designed to clarify which
ghrelin brain targets participate in the short-term orexigenic actions
of ghrelin. First, c-Fos induction into mouse brains centrally or
peripherally treated with ghrelin was analyzed. It was confirmed that
peripherally administered ghrelin dose dependently increases food intake
and mainly activates c-Fos in ARC neurons. In contrast, centrally
administered ghrelin activates c-Fos in a larger number of brain nuclei.
To determine which nuclei are directly accessible to ghrelin, mice were
centrally or peripherally injected with a fluorescent ghrelin tracer.
It was found that peripherally injected tracer mainly accesses the ARC
while centrally injected tracer reaches most brain areas known to
express ghrelin receptors. Following that, ghrelin effects in
ARC-ablated mice were tested and it was found that these mice failed to
increase food intake in response to peripherally administered ghrelin
but fully responded to centrally administered ghrelin. ARC-ablated mice
showed similar patterns of ghrelin-induced c-Fos expression as seen in
control mice with the exception of the ARC, where no c-Fos was found.
Thus, peripheral ghrelin mainly accesses the ARC, which is required for
the orexigenic effects of the hormone. Central ghrelin accesses a
variety of nuclei, which can mediate the orexigenic effects of the
hormone even in the absence of an intact ARC.