FIGURE 4.

Increasing NAD⁺ levels decreases basal mitochondrial oxygen consumption rate in astrocytes. A, oxygen consumption rate (OCR) determined for basal conditions in confluent non-transgenic (NonTG) and hSOD1^G93A (G93A) spinal cord astrocyte monolayers 24 h after treatment with vehicle (Control) or 5 mm NMN. B, ATP content in confluent non-transgenic and hSOD1^G93A spinal cord astrocyte cultures 24 h after treatment with vehicle or 5 mm NMN. C, non-transgenic and hSOD1^G93A spinal cord astrocyte cultures were treated with vehicle or 5 mm NMN, and 24 h later the relative mitochondrial to nuclear DNA ratio was estimated by real time PCR using primers specific for cytochrome c oxidase II (COX2) and lipoprotein lipase (LPL). D, relative expression of Ppargc1a, Ppargc1b, Nrf1, and Gabpa mRNA in spinal cord astrocyte cultures 24 h after treatment with 5 mm NMN. mRNA levels were determined by real time PCR and corrected by Actin mRNA levels. For all panels, each data point represents the mean ± S.D. (error bars) of at least three independent experiments. *, significantly different from vehicle treated non-transgenic astrocytes (p < 0.05). prot., protein.