Melatonin

high-resolution terminology - matching measurements at high-resolution

Melatonin

Description

Melatonin (N-acetyl-5-methoxytryptamine, aMT) is a highly conserved molecule present in unicellular to vertebrate organisms. Melatonin is synthesized from tryptophan in the pinealocytes by the pineal gland and also is produced in other organs, tissues and fluids (extrapineal melatonin). Melatonin has lipophilic and hydrophilic nature which allows it to cross biological membranes. Therefore, melatonin is present in all subcellular compartments predominantly in the nucleus and mitochondria. Melatonin has pleiotropic functions with powerful antioxidant, anti-inflammatory and oncostatic effects at the level of mitochondria.

Abbreviation: aMT

Reference: Reiter 2003 Acta Biochim Pol; Acuña-Castroviejo 2014 Cell Mol Life Sci

Melatonin and attenuation of mitochondrial oxidative damage

Doerrier C (2015) Melatonin attenuates mitochondrial oxidative damage. Mitochondr Physiol Network 2015-03-03.

Doerrier C (2015) MiPNet

Abstract: Melatonin (aMT) is a potent antioxidant and anti-inflammatory molecule able to attenuate mitochondrial oxidative damage, preserving mitochondrial function and organization.

• O2k-Network Lab: AT Innsbruck Gnaiger E

Testing melatonin

Several publications show that melatonin protects against heart isquemia-reperfusion (IR) injury. However, in vitro studies about the protective effects of melatonin on IR were performed in perfused isolated rat heart. Numerous publications demonstrated the protective role of melatonin against the damage due to oxidative-nitrosative stress in isolated mitochondria in different pathologies. For this reason, we expect cardiac protection of melatonin in IR in our mitochondrial preparations.

To evaluate the cardioprotective effect of melatonin against IR in isolated mitochondria, we should check the optimal melatonin concentration and the time needed to protect the mitochondria. In IR studies used a range 1-100 µM (where 50 µM presented the maximal protection and 25 µM was ineffective) of melatonin. However, some studies in isolated mitochondria employed melatonin in a nanomolar range: 1-100 nM.

In consequence, we should evaluate several melatonin concentrations (dose-dependent curve) to know the optimal melatonin concentration in our experimental model.

I propose to do in several O2k chambers the following experiments:

1. A specific protocol without melatonin and without anoxia-reox.
2. The same protocol without melatonin in anoxia-reox conditions.
3. Anoxia-reox with melatonin: several [aMT].

Melatonin concentrations

µM range:

1 µM, 25 µM, 50 µM, 100 µM

Perhaps, we need lower melatonin concentration in isolated mitochondria. For this reason, we could evaluate a nM range:

1 nM, 25 nM, 50 nM, 75 nM, 100 nM

Run 1:

P1 Without melatonin and without anoxia-reox/ without melatonin in anoxia-reox condition

P2 → Anoxia-reox with melatonin: 1 µM/ 50 µM [aMT]

P3 → Anoxia-reox with melatonin: 100 µM/ 25 µM [aMT]

P4 → Anoxia-reox with melatonin: 1 nM/ 50 nM [aMT]

P5 → Anoxia-reox with melatonin: 100 nM/ 25 nM [aMT]

P6 → Anoxia-reox with melatonin: 75 nM/ 100 nM [aMT]

Run 2:

Repeat run 1.

Range evaluated: 0.001 µM – 100 µM

In the first step we could add melatonin at the beginning of the experiment (before anoxia). Once the adequate melatonin concentration is found, we should check the time necessary with this melatonin concentration, and if the main protective effect exists with melatonin administration in different points of the experiment (for example, only before anoxia or before anoxia and prior reoxigenation).

Sources of melatonin

• SIGMA: Price: 250 mg, 41€; Reference: M5250.
  
• FAGRON:

Melatonin DAC:

500 mg - 20,30?

1 g - 31,60?

5g - 129,-?

25g - 514,-?

Contact: Berta Gilanido, Email: [email protected]

Reference: 33457-27

Darío recommendation: much higher quality.