This research aims to identify measurable changes in the central nervous system (CNS) of adult and larval zebrafish which are linked to pain perception, and to use these to refine zebrafish experiments by identifying effective analgesics.
The zebrafish is increasingly being used in biomedical research. Relatively little is known about pain perception (nociception) and effective analgesics in zebrafish. This research aims to help address this knowledge gap.
Efforts are underway to establish non-invasive measures of nociception, such as altered behaviour and cortisol measurements. This research aims to firmly link such measures to nociception, by establishing specific changes in gene expression and endogenous opiates in the CNS elicited by noxious stimuli. These will then be used to refine zebrafish experiments to minimise suffering by determining how a range of analgesics reduce nociception-related gene expression.
Research details and methods
This research will focus on identifying changes in the expression of immediate early genes and endogenous opiates in the dorsal horn of the spinal cord, where primary nociception processing takes place. These changes will be identified following intramuscular injection of mustard oil in adult fish and compared to control groups receiving injections of vehicle only.
Once candidate gene expression and endogenous opiate changes have been identified, the research will determine how potential analgesics reduce nociception-related gene expression, identifying those which function effectively in zebrafish.
The zebrafish is increasingly being used in biomedical research, because it is a cost-effective vertebrate model organism. However, most of the more than 400.000 procedures per year are performed without analgesia, because there is a lack of knowledge regarding nociception and effective analgesics in this important laboratory species.
Efforts are underway to establish non-invasive measures of nociception, such as altered behaviour and cortisol measurements. To firmly link such measures to nociception, changes in genes expression elicited by noxious stimuli in the CNS need to be established. In this pilot project, we propose to analyse gene expression changes of immediate early genes and endogenous opiates in the dorsal horn of the spinal cord, where primary nociception processing takes place, and in higher brain centres. Our preliminary findings indicate that c-fos expression is selectively increased in the dorsal horn and pro-enkephalin expression is increased in the brainstem of adult fish that received an intramuscular injection of mustard oil, compared to those that received a vehicle injection. This suggests that gene expression changes specifically related to nociception and not just to handling stress can be measured.
We will conduct similar experiments in larval zebrafish and, importantly, will determine how potential analgesics reduce nociception-related gene expression. Our experiments will elucidate central nociception in zebrafish and will inform other studies using non-invasive measurements regarding the relevance of these measures to nociception. Our ultimate goal is to contribute to the refinement of procedures conducted on zebrafish by devising effective ways of analgesia and validating non-invasive measurements of these.