Reduced [3H]cyclic AMP binding in postmortem brain from subjects with bipolar affective disorder.
Findings of increased Gs alpha levels and forskolin-stimulated adenylyl cyclase activity in selective cerebral cortical postmortem brain regions in bipolar affective disorder (BD) implicate increased cyclic AMP (cAMP)-mediated signaling in this illness. Accumulating evidence suggests that intracellular levels of cAMP modulate the abundance and disposition of the regulatory subunits of cAMP-dependent protein kinase (cAMP-dPK). Thus, in the present study, we tested further whether hyperfunctional Gs alpha-linked cAMP signaling occurs in BD by determining [3H]cAMP binding, a measure of the levels of regulatory subunits of cAMP-dPK, in cytosolic and membrane fractions from discrete brain regions of postmortem BD brain. Specific [3H]cAMP (5 nM) binding was determined in autopsied brain obtained from 10 patients with DSM-III-R diagnoses of BD compared with age- and postmortem delay-matched controls. [3H]cAMP binding was significantly reduced across all brain regions in cytosolic fractions of BD frontal (-22%), temporal (-23%), occipital (-22%) and parietal (-15%) cortex, cerebellum (-36%), and thalamus (-13%) compared with controls, but there were no differences in [3H]cAMP binding in the membrane fractions from these same regions. These results suggest that changes occur in the cAMP-dPK regulatory subunits in BD brain, possibly resulting from increased cAMP signaling. The possibility that antemortem lithium and/or other mood stabilizer treatment may contribute to the above changes, however, cannot be ruled out.
Rahman
S
S
Section of Biochemical Psychiatry, Clarke Institute of Psychiatry, Toronto, Ontario, Canada.
Li
P P
PP
Young
L T
LT
Kofman
O
O
Kish
S J
SJ
Warsh
J J
JJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001714:Bipolar Disorder / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D002102:Cadaver; D000242:Cyclic AMP / Q000378:metabolism*; D005260:Female; D006801:Humans; D008094:Lithium / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution; D014316:Tritium
D014316:Tritium; D008094:Lithium; D000242:Cyclic AMP