The hypothalamus produces
digoxin, an endogenous membrane Na+-K+
ATPase inhibitor and regulator of neurotransmission.
Digoxin being a steroidal
glycoside, is synthesised by the
isoprenoid pathway. In view of the reports of elevated
digoxin levels in
metabolic syndrome X with high body mass index, the
isoprenoid pathway mediated biochemical cascade was assessed in individuals with high and low body mass index. It was also assessed in individuals with differing hemispheric dominance to find out the relationship between
digoxin status, body mass index and hemispheric dominance. The
isoprenoid pathway metabolites,
tryptophan /
tyrosine catabolic patterns and membrane composition were assessed. In individuals with high body mass index an upregulated
isoprenoid pathway with increased
HMG CoA reductase activity, serum
digoxin and
dolichol levels and low
ubiquinone levels were observed. The RBC membrane Na+-K+
ATPase activity and serum
magnesium levels were decreased. The
tyrosine catabolites (
dopamine,
morphine,
epinephrine and
norepinephrine) were reduced and the
tryptophan catabolites (
serotonin,
quinolinic acid,
strychnine and
nicotine) were increased. There was an increase in membrane
cholesterol :
phospholipid ratio and a reduction in membrane
glycoconjugates in individuals with high body mass index. The reverse patterns were seen in individuals with low body mass index. The patterns in individuals with high body mass index and low body mass index correlated with right hemispheric dominance and left hemispheric dominance respectively. Hemispheric dominance and
digoxin status regulates the differential metabolic pattern observed in individuals with high and low body mass index.