A novel endogenous indole protects rodent mitochondria and extends rotifer lifespan - PubMed (original) (raw)

A novel endogenous indole protects rodent mitochondria and extends rotifer lifespan

Burkhard Poeggeler et al. PLoS One. 2010.

Abstract

Aging is a multi-factorial process, however, it is generally accepted that reactive oxygen species (ROS) are significant contributors. Mitochondria are important players in the aging process because they produce most of the cellular ROS. Despite the strength of the free-radical hypothesis, the use of free radical scavengers to delay aging has generated mixed results in vertebrate models, and clinical evidence of efficacy is lacking. This is in part due to the production of pro-oxidant metabolites by many antioxidants while scavenging ROS, which counteract their potentially beneficial effects. As such, a more effective approach is to enhance mitochondrial metabolism by reducing electron leakage with attendant reduction of ROS generation. Here, we report on the actions of a novel endogenous indole derivative, indolepropionamide (IPAM), which is similar in structure to melatonin. Our results suggest that IPAM binds to the rate-limiting component of oxidative phosphorylation in complex I of the respiratory chain and acts as a stabilizer of energy metabolism, thereby reducing ROS production. IPAM reversed the age-dependent decline of mitochondrial energetic capacity and increased rotifer lifespan, and it may, in fact, constitute a novel endogenous anti-aging substance of physiological importance.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1

Figure 1. Fluorometric HPLC detection of IPAM, melatonin and IPA in the brain of one-month-old male Sprague-Dawley rats: Peaks with identical elution times as synthetic IPAM, melatonin and IPA were consistently observed in rat brain.

a) One hour after administration of 300 mg/kg L-tryptophan, IPAM (1), melatonin (2) and indole-3-propionic acid (3) concentrations reached levels of 346±9 (IPAM), 713±32 (MEL) and 281±14 (IPA) pg indole/mg protein, respectively, in rat brain (n = 6). b) Co-elution of the endogenous indoles IPAM, melatonin and IPA along with the standards of these indole compounds results in larger single elution peaks representing endogenous

plus

exogenous indoles. c) Synthetic IPAM standard (1 ng) eluted at 30 minutes. Inset shows predicted structure of synthetic IPAM.

Figure 2

Figure 2. Mitochondrial membrane potential in mV: Effects of age and indole agents.

Mitochondrial membrane potential in mV (mean ± SEM) measured in rat brain mitochondria from young and old animals (male Sprague-Dawley rats, n = 6) with effects of melatonin, IPA and IPAM at 10 nM. All compounds were significantly different from control at both 1 month and 20 months, with IPAM showing significantly greater effects than melatonin or IPA. a- significantly different from control (p<0.0005); b- significantly different from melatonin and IPA (p<0.01).

Figure 3

Figure 3. Mitochondrial membrane potential in mV: Effects of age, toxins and IPAM.

Mitochondrial membrane potential in mV (mean ± SEM) was measured in rat brain mitochondria from young and old animals (male Sprague-Dawley rats, N = 6). The toxins doxorubicin (DOX), antimycin A (AmA) and FCCP at concentrations of 500 nM led to significant reductions in membrane potential as compared to control. Co-administration of IPAM at 10 nM significantly antagonized the effects of each toxin. In fact, the toxicity of doxorubicin and antimycin A was completely abrogated by IPAM to levels comparable to control. a- significantly different from control (p<0.05); b-significantly different from control (p<0.001); c- significantly different from toxin only (p<0.05); d-significantly different from toxin only (p<0.005).

Figure 4

Figure 4. Activity of mitochondrial complex I and IV: Effects of age and indole agents on ferric cyanide reduction and cytochrome c oxidation.

The activities of mitochondrial complex I (A) and complex IV (B) expressed in µmol/min/mg protein (mean ± SEM) were measured in mice brain mitochondrial preparations from young and old animals (male Swiss Webster mice, n = 10). Melatonin and IPAM were used at 10 nM concentration. Only IPAM consistently significantly increased complex I and IV activities compared to control. The results for complex I were verified by a second method in which the activity of the mitochondrial iron sulfur cluster N2 in complex I was determined by the nitroblue tetrazolium (NBT) reduction assay as µmol diformazan formed/minute/mg of mitochondrial protein (mean ± SEM) (C). a-significantly different from control (p<0.05); b-significantly different from control (p<0.005); c- significantly different from control (p<0.001).

Figure 5

Figure 5. Pro- and antioxidant effects of indole agents expressed as hydroxyl radical adducts of salicylate (percentage of control, no test agent added).

Pro- and antioxidant effects of indole agents as demonstrated as percentage of hydroxyl radical adducts formed from salicylate oxidation to 2,3- and 2,5-dihydroxybenzoic acids (DHBAs) versus control (incubation system without test agents: 100±2.8%, mean ± SEM, n = 6).

Figure 6

Figure 6. Lifespan extension in rotifers.

In rotifers (n = 11) IPAM at 10, 20 and 30 µM markedly extended the lifespan of rotifers. These effects were dose dependent and highly significant at all concentrations tested (p values <0.001 for all concentrations versus the control group (A). IPAM treatment of rotifers for 15 days at 30 µM daily resulted in a significantly increased size (B). Representative size differences are illustrated in animals treated either with vehicle for 15 days (C) or IPAM (D) for 15 days. Magnification X 90. The number of offspring for individual parents (E), as well as the number of reproductive days (F) during lifetime was significantly increased with IPAM (n = 10). a- significantly different from control (p<0.0001).

References

    1. Chyan YJ, Poeggeler B, Omar RA, Chain DG, Frangione B, et al. Potent neuroprotective properties against the Alzheimer beta-amyloid by an endogenous melatonin-related indole structure, indole-3-propionic acid. J Biol Chem. 1999;274:21937–21942. - PubMed
    1. Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis. Jama. 2007;297:842–857. - PubMed
    1. Sohal RS, Mockett RJ, Orr WC. Current issues concerning the role of oxidative stress in aging: a perspective. Results Probl Cell Differ. 2000;29:45–66. - PubMed
    1. Harman D. The biologic clock: the mitochondria? J Am Geriatr Soc. 1972;20:145–147. - PubMed
    1. Boveris A, Oshino N, Chance B. The cellular production of hydrogen peroxide. Biochem J. 1972;128:617–630. - PMC - PubMed

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