In the present study, the
neuroprotective effects of the
adipokine leptin, and the molecular mechanism involved, have been studied in rat and mice cortical neurons exposed to
N-methyl-d-aspartate (
NMDA) in vitro. In rat cortical neurons,
leptin elicited
neuroprotective effects against
NMDA-induced cell death, which were concentration-dependent (10-100 ng/ml) and largest when the
adipokine was preincubated for 2h before the neurotoxic stimulus. In both rat and mouse cortical neurons,
leptin-induced neuroprotection was fully antagonized by
paxilline (Pax, 0.01-1 μM) and
iberiotoxin (
Ibtx, 1-100 nM), with EC50s of 38 ± 10 nM and 5 ± 2 nM for Pax and
Ibtx, respectively, close to those reported for Pax- and
Ibtx-induced Ca(2+)- and voltage-activated K(+) channels (Slo1
BK channels) blockade; the
BK channel opener
NS1619 (1-30 μM) induced a concentration-dependent protection against
NMDA-induced excitotoxicity. Moreover, cortical neurons from mice lacking one or both alleles coding for Slo1
BK channel pore-forming subunits were insensitive to
leptin-induced neuroprotection. Finally,
leptin exposure dose-dependently (10-100 ng/ml) increased intracellular Ca(2+) levels in rat cortical neurons. In conclusion, our results suggest that Slo1
BK channel activation following increases in intracellular Ca(2+) levels is a critical step for
leptin-induced neuroprotection in
NMDA-exposed cortical neurons in vitro, thus highlighting
leptin-based intervention via
BK channel activation as a potential strategy to counteract
neurodegenerative diseases.