I am looking to perform an assay for cold sensation to evaluate a model of immune-mediated neuropathy.
I suspect that the treatment will make the animals more sensitive to cold stimuli, but things could go either way so I want a test that can see both increases and reductions in cold sensation.
I also want an assay that is not too onerous to perform and has as clear a behavior as possible (minimize subjectivity).
Options I’ve seen include:
Acetone test
Cold plate assay
Latency to nocifensive behavior
Number of flinches over 5 min period @ 10ºC (see below)
We obtained good and reliable results using the dry ice test for cold allodynia. In CIPN pain model, I can see a clear reduction on paw withdraw latency in treated mice. I’ve also used acetone test, but I find more variable results compared to dry ice.
One of my colleagues brought to my attention this device developed by @stevedavidson and team
The cooling plate mechanism was adapated by Madasu and colleagues in this preprint
I’m optimistic about the cold plate type assays counting jumps or other nocifensive behaviors. The low-cost home-made cold plate is also attractive. Thanks @stevedavidson for coming up with this.
We’ve been doing cold plantar. Issues we’ve run into is mice not responding before the cutoff (20s). We are using the correct glass (1/4"). Any thoughts @tonellor and @liz ? I’m inclined to move on to other assays, but I’m glad it work for you and many others.
Reviewing our students’ recent cold plantar data, I don’t see any mice that failed to respond within the 20 sec cutoff time. Our typical withdrawal latency for a naive adult mouse is in the ballpark of ~8-12 sec. This is with 3/16" borosilicate glass, so your times might be a little bit longer, but certainly within 20 sec. I know you specifically said you were using the correct glass, but I wonder if it’s made of a different type of glass that doesn’t conduct heat/cold as well? It just seems really weird to me that your mice aren’t responding.
We use the acetone test - which is quick and easy.
On a side note, I recently had to get a root canal and my dentist performed a “cold hypersensitivity” test on me. They sprayed liquid nitrogen on a cotton swab and placed it against my infected tooth and non-infected tooth. They recorded the time I was in pain after both applications. However, what I didn’t expect was how excruciating the the cold pain was in my infected tooth. I was flopping around like child on the table. I felt “pain” and “cold” in that tooth until I went to bed that night, about 12 hours later. Absolutely blew my mind.
My thoughts and point to all this is that if the animals are neuropathic, if they are in pain, and are cold hypersensitive - then they should have exaggerated cold responses to any cold stimulus in any assay. Maybe I am wrong, but I don’t think assay is as critical.
Sorry you went through that experience @sshiers but it sounds like you got some insight into cold pain. I think the assay is important insofar as the responses are unambiguous and the assay is efficient to perform. Acetone gets mixed reviews depending on whom I ask. I’m glad it works for you all.
