I asked similar question some time ago and i want to try to get the help once more! During experiments with abdominal writhing induced with acetic acid very different results are obtained! In the same group (control with vehicle) large discrepancy in number of writhing is observed? Also different publications are saying that in 20 minutes the animal has like 100 wriths! That is unbelievable for me! I have never seen more that c.a. 45 wriths during 20 minutes!
Hi Nikola,
Firstly let me say I have never done the AA writing test but have read about it as am studying another acute visceral model. I often see wide variation in behavioural outcomes, and there are many possible reasons!
Some things to consider:
Do you always carry out testing at the same time of day?
Is it always the same experimenter? (Some studies have suggested male experimenters can influence expression of pain behaviours - see Sorge et al., 2014)
Also, different methods of quantifying writing (i.e. automated, manual, classification of a 'writhe') could explain differences between what you see and published data, plus factors such as strain, species, handling, housing, lighting, noise levels etc etc etc
Thank you for your answers!
Fistr to Ali Abdil Razzaq Muhammed Noori Aldallal : in those publications there is nothing that helps me with my problem sincerely! I know how the test is performed and all ethical issues concerning the animal handling are perfectly clear! Nothing in those papers helps/solves my issue!
To Rosie: Yes im aware of all possible influences. First, experiments are done mostly from 9:00AM - 11:30AM some times few hours after but rarely! The description of writhe is quiet clear and im flowing standard descriptions, handling and housing and other things are almost same always and I think it wouldn't produce such discrepancy (only normal SD/SE)!
Still the results are as they are...
Ach the results are what they are then! Sounds like you are aware of the confounds so as long as you mention that in the write-up, there's no reason for the data to not be valid, even if it is highly variable!
If you are doing the experiment in batches, might be worth looking to see if one batch was particularly variable and consider excluding them? Or at least re-analyzing with them omitted? I recently had a similar problem with some extremely jumpy rats - all the conditions were the same but from the day they arrived, they went mental! No such issues with other batches - sometimes these things happen :)
If you really want to be sure of the literature, I would suggest doing a rough systematic review, noting species, strain, country, temp/humidity of housing, group/solitary housing, lighting, sex, handling, weight, age, and protocol details so you can easily see where differences might be coming from.
Good luck!
We had also problem with extremely jumpy mice :D Thanks any way
Hi Nikola,
I have ran this assay and you are correct. in the 5-20 min period I saw an average of 50 wriths. Also, CD1 mice should not be too jumpy
You can check out any publications from the Pain group at Abbott Laboratories (i.e. Michael Decker)
I hope this helps,
Gricelda