Basic & clinical pharmacology & toxicology
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Basic Clin. Pharmacol. Toxicol. · Jul 2006
Spinal nociception induced by intramuscular injection of oxytetracycline preparations in rats and pigs.
Some drug formulations for intramuscular use may cause damage, which potentially can be associated with pain. In animals, spinal nociception can be assessed by stereological quantification of number of regional dorsal horn neurones containing intranuclear Fos-protein as a consequence of expression of the c-fos gene. The aim of the present study was to use c-fos gene expression as a measure of nociceptive input after intramuscular injection of different oxytetracycline formulations. ⋯ In pigs receiving an Aquacyklin injection, the number of Fos-positive neurones was 3,493+/-2,027, which was not significantly higher than the previously determined basal level. The increased neuronal activation after intramuscular injection of Maxicyklin Vet. may suggest that injection of this drug may be more painful than injection with saline. In contrast, no significant difference in neuronal activation caused by saline and Engemycin Vet. was found.