Abstract
The local gill production of corticotropin releasing hormone (
crh
) and
crh
-receptor (
crhr
) is hypothesized to play important roles during seawater (SW) and freshwater (FW) acclimation in euryhaline black porgy (
Acanthopagrus schlegelii
). The mRNA expression of
crh
,
crhr
, and
Na
+
/
K
+
-ATPase
(
a-nka
) was examined in SW and FW diencephalon (Dien) and in the gills at different exposure time by Q-PCR analysis. The
in situ
hybridization results indicate that
crh
mRNA hybridization signals were more abundant in FW fish in the gigantocellular (PMgc) and parvocellular (PMpc) part of the magnocellular preoptic nucleus versus SW fish. The
crh
and
crhr-
expressing cells were located in basal cells of gill filament. Furthermore,
in vitro
dexamethasone (DEX) treatment could increase the
crh
-system in the gill. Increased transcripts of the
crh
-system in the gill via
in vitro
and
in vivo
CRH treatments suggest that CRH may regulate the system in a local manner. The a-Nka cells were localized in the filament and secondary lamellae mitochondria rich cells (MRCs) of FW fish at 8 h and 1 day. a-Nka cells were seen in both filament and lamellae in the FW but much less in SW fish indicating that gills play key roles in black porgy osmoregulation. Gill
crh
and
crhr
play important roles in the response to salinity stress.