Good day. I am about to conduct a neuroprotective studies of an endemic plant extracts using Drosophila melanogaster as animal model. Most of the journal articles that I have read did not use positive control but I just want to know if there are any. Thank you very much.
It depends on the type of damage you are goingto induce and type of neuroprotection you are trying to evaluate, but I don't think the positive control is necessary in this case. As you said it yourself, most of the groups don't use one.
Best,
Jan
If I well understood you're going to study the efficacy of these extract as a neuroprotective compound. Thus you should have an established neurotoxic/neurodegenerative model with an established treating drug.
Usually in classical drug studies you should use positive controls. Doesn't matter if "other groups are not using it". This is not a correct "science" and, moreover, I met many protocols in my life that were not working at all..............
If you're interested in understanding the efficacy of your compound (and evaluating its realtive effect with respect other well known compounds) it is better to set a positive control, in my opinion.
1. set up your model (in drosophila there are a lot of different models on neurotoxicity/neurodegeneration) searching for the simpler one.
2. test your compound on this model and
3. test a known acting compound on the model you set up.
4. test the vehicle.
This is a classical drug test analysis on animals and there are specific protocols to apply it which can help you to.
Regarding drosophila, one interesting point is which phenotype are you going to study: behavioral, pathophysiological, developmental, life span etc. Adapt your model to the simplest one, giving you the maximum in terms of data.
Good Luck
A positive control would be valuable as a reference point for the degree of neuroprotection the plant offers. The agent to be selected is dependent on the likely mechanism of neuroprotection by the plant.
Ourlad, you might consider using Lithium Chloride as a neuroprotective positive control. I'm not sure how that could be administered to drosophila, nor how the dosing might translate. In any case, we used it successfully for neuroprotection in mice with physiologic and behavioral measures (see Lithium paper on my profile), and apparently others have also related Lithium's use as a protective agent in drosophila for similar purposes:
http://www.ncbi.nlm.nih.gov/pubmed/?term=lithium+neuroprotection+drosophila
In case it is helpful to you, we found that neuroprotective effects were found when the protective agent was administered at the same time as the chemical (or genetic switch) inducer of neurodegeneration. Cell models in vitro will often even pretreat cells with protective agent before inducing damage to get maximal protective effect (even though this sequence does not relate to a clinical reality where damage typically occurs first and neuroprotection efforts can only follow).
I think you have to make a positive control, otherwise it is not " correct" for the entire hypothesis of experiment
Hi Ourlad,
A very good positive control (in order to compare different plant derived compounds) are homogenized young barley leaves. At a concentration of 0.1mg/ml to 2mg/ml of barley leaf homogenate (dry weight) tested within mammalian cerebellar neuronal assays, this homogenate provokes around 50-70% neuroprotection under oxidative stress conditions when tested over 48hrs (0.5mM nitropropionic acid, a irreversible succinate dehydrogenase inhibitor serves as injury control and injury agent). Look at Gorba et al,., 2006 (Experimental Cell Research).
Good luck,
Frank
We have used Silymarin as a plant-derived neuroprotective agent in some of our previuos studies.
It is advisable to use a positive control ignorer to improve the validity of the experiments. Often manuscripts are rejected for these cause. Most importantly disease control and a standard Neuroprotective group is necessary to consolidate your hypothesis..
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