Table 3. Metabolic responses of cultured neurons derived from different brain regions to activating conditions.
| Brain region and harvest agea | Treatment | Response magnitudeb | Reference |
|---|---|---|---|
| Cerebral cortex | (Cortical neurons, a model for GABAergic neuronsa) | ||
| E14 | 5 → 50 mmol/L K+ | 10% ↑ DG phosphorylation | Peng et al, 1994 |
| 20% ↑ [U-14C]glucose to 14CO2 (low rate) | |||
| 20% ↓ [U-14C]lactate to 14CO2 | |||
| 115% ↑ [2-14C]pyruvate to 14CO2 (very low rate) | |||
| E16–17 | 1.4 μmol/L nitric oxide | 85% ↓ O2 uptake, no change in lactate production | Almeida et al, 2001 |
| 100 μmol/L Glutamate | No change in lactate production | Almeida et al, 2004 | |
| Overexpression of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 | 550% ↑glycolysis, 190% ↑lactate level, 50% ↓pentose phosphate shunt pathway (PPP) flux (control neurons: PPP flux=200% glycolytic flux) | Herrero-Mendez et al, 2009; Bolaños and Almeida, 2010 | |
| E17 | Hypoxia, 3 days | 200% ↑ glucose utilization | Malthankar-Phatak et al, 2008 |
| 330% ↑ lactate concentration in medium | |||
| E16–17 | Hypoxia for 24 hours | 200% ↑ lactate concentration in medium | Sher, 1990 |
| E15 | 55 mmol/L K+ | 50% ↑ cycling ratio for glutamate=increased TCA cycle activity | Waagepetersen et al, 2000 |
| E18 | 33 μmol/L Glutamate | 200–250% ↑ oxygen consumption with glucose substrate | Gleichmann et al, 2009 |
| 7–32 μmol/L FCCP | 200–250% ↑ oxygen consumption with glucose substrate | ||
| E15 | 25 nmol Dinitrophenol | 20% ↑ oxygen consumption with glucose substrate | Jameson et al, 1984 |
| E17 | 2 μmol/L amyloid-β1–42 , 4 days | 200% ↑ [1-14C]glucose to 14CO2; 155% ↑ [6-14C]glucose to 14CO2; 205% ↑ pentose phosphate shunt pathway | Soucek et al, 2003 |
| Cerebellum | (Cerebellar granule neurons, a model for glutamatergic neuronsa) | ||
| PN7 | 5 → 50 mmol/L K+ | 75% ↑ DG phosphorylation | Peng et al, 1994 |
| 120% ↑ [U-14C]glucose to 14CO2 | |||
| 20% ↑ [U-14C]lactate to 14CO2 | |||
| 110% ↑ [2-14C]pyruvate to 14CO2 | |||
| PN7 | 50 μmol/L Glutamate | 30% ↑ DG phosphorylation | Peng and Hertz, 2002 |
| 500 μmol/L Glutamate | 40% ↑ DG phosphorylation | ||
| 5.4 → 55 mmol/L K+ | 75% ↑ lactate production rate; 75% ↑ [U-14C]glucose to 14CO2 | ||
| PN8 | 25 nmol Dinitrophenol | 43% ↑ oxygen consumption with glucose substrate | Jameson et al, 1984 |
| PN6–7 | Hypoxia, 7h | 100% ↑ lactate production | Sonnewald et al, 1994 |
| PN8 | 100 μmol/L Glutamate | 115% ↑ DG uptake plus phosphorylation (10 minute assay) | Minervini et al, 1997 |
| 100 μmol/L NMDA | 180% ↑ DG uptake plus phosphorylation (10 minute assay) | ||
| 60 μmol/L Kainate | 220% ↑ DG uptake plus phosphorylation (10 minute assay) | ||
| 100 μmol/L Quisqualate | 55% ↑ DG uptake plus phosphorylation (10 minute assay) | ||
| PN5–7 | Respiration assays in 25 mmol/L K+ 2 μmol/L FCCP | 175% ↑ oxygen consumption with glucose substrate | Jekabsons and Nicholls, 2004 |
| 250 μmol/L Glutamate + 25 μmol/L glycine | 32–60% ↑ oxygen consumption with glucose substrate | ||
| 300 μmol/L NMDA | 33–36% ↑ oxygen consumption with glucose substrate | ||
| PN5–7 | Respiration assays in 3.9 mmol/L K+ 3 μmol/L FCCP | 250–325% ↑ oxygen consumption with glucose substrate | Yadava and Nicholls, 2007 |
| 100 μmol/L Glutamate + 10 μmol/L glycine | 250–325% ↑ oxygen consumption with glucose substrate | ||
| PN7–8 | DG assays in 3.9 mmol/L K+ | Ward et al, 2007 | |
| 100 μmol/L Glutamate + 10 μmol/L glycine for 10 minutes, then new medium with no glutamate + [3H]DG for 20 minutes | 50% ↑ DG phosphorylation (reflecting ↑ glucose utilization) | ||
| Hippocampus | |||
| Neurons in mixed | 500 μmol/L Glutamate or 20 μmol/L AMPA | 75–80% ↓ 2- or 6-NBDG uptake—fast, reversible | Porras et al, 2004 |
| Neuron–astrocyte | 75 μmol/L veratridine | No change in 6-NBDG uptake for ∼10 minutes, then 70% ↓ | |
| Cultures (PN1–3) | 40 mmol/L KCl | No effect on 6-NBDG uptake | |
| Neurons | 100 μmol/L Glutamate, 10 minutes | No effect on DG uptake | Patel and Brewer, 2003 |
| (E18) | 1 μmol/L FCCP + 10 mg/mL | 200% ↑ DG uptake at 5 minutes | |
| oligomycin 100 μmol/L Glutamate + 1 μmol/L FCCP + 10 mg/mL oligomycin | 135% ↑ DG uptake at 5 minutes | ||
| Neurons | Acute anoxia | 40% ↑ DG uptake | Yu et al, 2008 |
| (PN0) | Acute anoxia after hypoxic preconditioning, 20 minutes/day for 6 days | 90% ↑ DG uptake | |
AMPA, 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl)propanoic acid; DG, deoxyglucose; NBDG, N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)2-deoxyglucose; TCA, tricarboxylic acid.
The age at which tissue was obtained for cultured cells is denoted by E=embryonic or PN=postnatal, followed by the age in days. Cerebral cortical neuronal cultures obtained from ∼15-day-old embryos are used as a model system for GABAergic neurons, and cerebellar granule neurons obtained from ∼7 day-old postnatal rodents are used as a model system for glutamatergic neurons (Yu et al (1984); Schousboe et al (1985); Hertz et al (1988) cited references). It must be noted that culture conditions and duration, composition of the culture medium, and cellular development during time in culture influence characteristics of the cultures (e.g., Hertz et al (1998); Hertz (2004) cited references).
Magnitude of response is expressed as approximate percentage change owing to treatment, 100[(treated−control)/control)]. DG assays are typically used to measure hexokinase-dependent phosphorylation as a measure of glucose utilization. 2-NBDG is a fluorescent glucose analog that is transported and phosphorylated, whereas 6-NBDG is transported but not phosphorylated. Brief assays (<5 minutes) with DG or 2-NBDG measure mainly transport (uptake), intermediate duration assays (5–10 minutes) can represent transport plus phosphorylation depending on washout of unmetabolized precursor from cells at the end of the assay, and longer assays with DG or 2-NBDG reflect mainly phosphorylation that can be overestimated somewhat if unmetabolized precursor is not completely washed out. 6-NBDG accumulation reflects transport until intracellular and extracellular levels equilibrate. See legend to Table 4 for more details related to sites of action of metabolic inhibitors.