The Osmotic
Component of Ethanol and Urea Action is Critical
for Their Immediate Stimulation of
Thyrotropin-Releasing Hormone (TRH) Release from
Rat Brain Septum
J. KUČEROVÁ, V.
ŠTRBÁK
Laboratory
of Neurohumoral Regulations, Institute of
Experimental Endocrinology, Center of Excellence
supported by European Commission, Slovak Academy
of Sciences, Bratislava, Slovak Republic
Received
March 23, 2000
Accepted September 25, 2000
Summary
There
is considerable evidence linking alcohol
consumption and sedation and TRH in the brain
septum. Moreover, innate septal TRH concentration
is inversely related to the degree of ethanol
preference. Recently we demonstrated in rats that
four-week ethanol drinking increased the septal
TRH content by 50 %. We had shown previously that
ethanol induces neuronal swelling, which is known
to evoke the secretion of hormones, peptides and
amino acids from various types of cells. We have
therefore explored the effect of hyposmotic
medium and of 80 and 160 mM ethanol and 80 mM
urea (both permeant molecules) in isosmotic and
hyperosmotic (preventing cell swelling) media on
the in vitro release of TRH by the rat septum.
Lowering medium osmolarity resulted in a
hyposmolarity-related increase in TRH secretion.
Both ethanol and urea stimulated TRH release only
in isosmolar solution. Our data indicate that
ethanol in clinically relevant concentrations can
induce TRH release from the septum by a mechanism
involving neuronal swelling.
Key
words
Ethanol
· TRH · Septum · Cell volume · Urea
Reprint
requests
Vladimír Štrbák, M.D., Institute of
Experimental Endocrinology, Slovak Academy of
Sciences, Vlárska 3, Bratislava 83306, Slovakia
, fax: 421-7-54774247, e-mail: ueenstrb@savba.savba.sk
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