NAD+ and nicotinamide: sex differences in cerebral ischemia.
Neuroscience 2013;
237:223-31. [PMID:
23403179 DOI:
10.1016/j.neuroscience.2013.01.068]
[Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 01/29/2013] [Accepted: 01/29/2013] [Indexed: 11/22/2022]
Abstract
BACKGROUND
Previous literature suggests that cell death pathways activated after cerebral ischemia differ between the sexes. While caspase-dependent mechanisms predominate in the female brain, caspase-independent cell death induced by the activation of poly(ADP-ribose) polymerase (PARP) predominates in the male brain. PARP-1 gene deletion decreases infarction volume in the male brain, but paradoxically increases damage in PARP-1 knockout females.
PURPOSE
This study examined stroke-induced changes in NAD+, a key energy molecule involved in PARP-1 activation in both sexes.
METHODS
Mice were subjected to middle cerebral artery occlusion and NAD+ levels were assessed. Caspase-3 activity and nuclear translocation were assessed 6h after ischemia. In additional cohorts, Nicotinamide (500 mg/kg i.p.) a precursor of NAD+ or vehicle was administered and infarction volume was measured 24h after ischemia.
RESULTS
Males have higher baseline NAD+ levels than females. Significant stroke-induced NAD+ depletion occurred in males and ovariectomized females but not in intact females. PARP-1 deletion prevented the stroke-induced loss in NAD+ in males, but worsened NAD+ loss in PARP-1 deficient females. Preventing NAD+ loss with nicotinamide reduced infarct in wild-type males and PARP-1 knockout mice of both sexes, with no effect in WT females. Caspase-3 activity was significantly increased in PARP-1 knockout females compared to males and wild-type females, this was reversed with nicotinamide.
CONCLUSIONS
Sex differences exist in baseline and stroke-induced NAD+ levels. Nicotinamide protected males and PARP knockout mice, but had minimal effects in the wild-type female brain. This may be secondary to differences in energy metabolism between the sexes.
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