Propofol (2,6-diisopropylphenol) is an applicable immersion anesthetic in the axolotl with potential uses in hemodynamic and neurophysiological experiments.

Mathias Møller Thygesen,Michael Pedersen,Mikkel Mylius Rasmussen,Jesper Guldsmed Madsen,Henrik Lauridsen

doi:10.1002/reg2.80

Mathias Møller Thygesen, Michael Pedersen + Show 3 more

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https://doi.org/10.1002/reg2.80

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Abstract

The Mexican axolotl (Ambystoma mexicanum) is an important model species in regenerative biology. Traditionally, axolotls are anesthetized using benzocaine or MS‐222, both of which act to inhibit voltage gated sodium channels thereby preventing action potential propagation. In some neurophysiological experiments this is not desirable; therefore we tested propofol as an alternative anesthetic in the axolotl. We evaluated benzocaine, MS‐222, and propofol's cardiovascular effects, effects on action potential propagation in the spinal cord, and gross limb regenerative effects. We found that propofol is applicable as a general anesthetic in the axolotl allowing for neurophysiological experiments and yielding a stable anesthesia with significantly less cardiovascular effect than both benzocaine and MS‐222. Additionally, propofol did not affect gross limb regeneration. In conclusion we suggest the consideration of propofol as an alternative immersion anesthetic to benzocaine and MS‐222.

Highlights

The Mexican axolotl (Ambystoma mexicanum) has an impressive regenerative potential and has been applied as a model for intrinsic tissue regeneration of various organs and tissues (Armstrong & Malacinski, 1989; McCusker & Gardiner, 2011; Roy & Gatien, 2008)
We found that propofol is applicable as a general anesthetic in the axolotl allowing for neurophysiological experiments and yielding a stable anesthesia with significantly less cardiovascular effect than both benzocaine and MS-222
Benzocaine had no significant effect on stroke volumes (SVs) during anesthesia, but it significantly increased SV by 1.26-fold after recovery compared to baseline (Fig. 1G, K)

Summary

Introduction

The Mexican axolotl (Ambystoma mexicanum) has an impressive regenerative potential and has been applied as a model for intrinsic tissue regeneration of various organs and tissues (Armstrong & Malacinski, 1989; McCusker & Gardiner, 2011; Roy & Gatien, 2008). Axolotls can be kept under anesthesia for several hours allowing for complex surgical and imaging procedures with no subsequent adverse effects related to the anesthetic Both benzocaine and MS-222 act to inhibit the axonal voltage gated sodium channels, thereby preventing or reducing the propagation of action potentials in the nervous system (Baker, 2000; Butler & Ward, 1965; Chevallier, Landry, Nagy, & Cabelguen, 2004; Guven, Mert, & Gunay, 2005). It follows that these types of anesthetics have obvious drawbacks when performing electrophysiological experiments on sedated animals, since the conduction pathways are inhibited during anesthesia. Inspired by the need to measure the presence/absence of conduction in the regenerating spinal cord of the axolotl under anesthesia, we set out to find an alternative to the traditional anesthesia regimes used for this animal and to test the applicability of this alternative in relevant situations for the use of the animal

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