Over the last 15 years I have been involved in the pain field initially in research and then in clinical practice. I regularly attend scientific meetings. It continues to amaze me the amount of pain research done on mice/rats. Honestly, I do not think the findings in mice/rats are transferable to complex conditions like human pain. For a very simplistic and partial view please see my section about pain mechanisms. The result of so many billions of dollars spent on animal pain research is very lacking. Not much in terms of treatments came out of this research.
At recent scientific meetings the hype was about how male mice and female mice are different. Some researchers seem to believe that because most research was done on male mice, the results were not suitable for translational (treatment finding) research. Following this reasoning I am baffled that they do not realize that the difference between female mice and male mice is much much smaller than the difference between humans and mice. Humans are very different creatures. Recently I saw an article in the journal Nature describing the significant differences between the brain neurons in humans and mice: Hodge RD et al. Nature. 2019 Sep;573(7772):61-68. One of the conclusions of this paper is: “Notably, serotonin receptors are the second-most-divergent gene family, challenging the use of mouse models for many neuropsychiatric disorders that involve serotonin signalling.” Pain circuits are intimately connected to the the brain areas involved in various psychiatric diseases (e.g. anxiety, depression). Earlier this year one article that was very hyped on the internet talked about the areas of amygdala in mouse that seem to be important for the “unpleasantness of pain”: Corder G et al. Science. 2019 Jan 18;363(6424):276-281. I find it hard to believe that the findings of the Corder G et al. paper will have any importance for the human pain.
I think we should focus on animal research only to understand the fundamental mechanisms of biology (e.g cell biology, molecular biology) and use human research to understand complex diseases like pain. Even the fundamental mechanisms at the cellular level do not always translate from mice to humans. There are a few studies looking at functional knockouts in humans that were not predicted from studies in mice: Saleheen D et al. Nature. 2017 Apr 12; 544(7649): 235–239 and Narasimhan VM et al. Science. 2016 Apr 22; 352(6284): 474–477.