TGFbeta2 mediates rapid inhibition of calcium influx in identified cholinergic basal forebrain neurons.
Transforming growth factors betas (TGFbetas) are known to have important roles in neuronal survival and can be upregulated in disease. However, unlike many other trophic factors, nothing is known about the rapid neurotransmitter-like actions of TGFbeta in the CNS. We explored this by examining the effects of TGFbeta on calcium influx of large enzymatically dissociated basal forebrain neurons. We show that brief application of TGFbeta2, but not TGFbeta1, to fura-2AM-loaded neurons reversibly and acutely (within seconds) inhibited K(+)-evoked calcium influx. Moreover, using single-cell RT-PCR, we confirmed that the large TGFbeta2-responsive neurons presented a cholinergic phenotype. Investigation of the signaling mechanism underlying TGFbeta2 actions using whole-cell recordings of calcium currents revealed that TGFbeta2-mediated responses were insensitive to the nonhydrolyzable GTP analogue GTPgammaS. However, TGFbeta2-mediated calcium current reductions were prevented by intracellular perfusion of a Smad2/3 peptide antagonist. Together, these results suggest that TGFbeta2 can acutely regulate the excitability of basal forebrain cholinergic neurons through an atypical signaling mechanism.
Williams
Sylvain
S
Douglas Hospital Research Center, McGill University, Montreal, Quebec, Canada. wilsyl@douglas.mcgill.ca
Souchelnytskyi
Serhiy
S
Danik
Marc
M
D000818:Animals; D001483:Base Sequence; D020013:Calcium Signaling / Q000187:drug effects*; D002795:Choline O-Acetyltransferase / Q000235:genetics; D002799:Cholinergic Fibers / Q000187:drug effects / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D005968:Glutamate Decarboxylase / Q000235:genetics; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000235:genetics; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism*; D016548:Prosencephalon / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015290:Second Messenger Systems; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D018076:DNA, Complementary; D007527:Isoenzymes; D016212:Transforming Growth Factor beta; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D002795:Choline O-Acetyltransferase; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1; C401141:glutamate decarboxylase 2