Nociception-Induced Changes in Electroencephalographic Activity and FOS Protein Expression in Piglets Undergoing Castration under Isoflurane Anaesthesia

Reiser, Judith; Kreuzer, Matthias; Werner, Julia; Saller, Anna M.; Fischer, Johannes; Senf, Steffanie; Deffner, Pauline; Abendschoen, Nora; Groll, Tanja; Grott, Andrea; Miller, Regina; Bergmann, Shana; Erhard, Michael H.; Ritzmann, Mathias; Zoels, Susanne; Schneider, Gerhard; Steiger, Katja und Baumgartner, Christine (2022): Nociception-Induced Changes in Electroencephalographic Activity and FOS Protein Expression in Piglets Undergoing Castration under Isoflurane Anaesthesia. In: Animals, Bd. 12, Nr. 18, 2309

Abstract

Simple Summary Efficient analgesia during surgical piglet castration is an important animal welfare issue. The present study is part of a larger study designed to investigate the efficacy of four local anaesthetics (bupivacaine, lidocaine, mepivacaine and procaine) for analgesia during castration. In conscious piglets, it is difficult to distinguish between stress, e.g., due to handling, and pain during castration. Therefore, this study was conducted under light isoflurane anaesthesia. The level of anaesthesia was adjusted such that movement reactions to a peripheral nociceptive stimulus still occurred. We present the results of the investigation of two possible parameters for the detection of nociception: the reaction pattern in the electroencephalogram (EEG) and FOS protein expression in the spinal dorsal horn. In the electroencephalogram, a biphasic reaction pattern in response to noxious stimulation was detected that was attenuated or altered by the application of local anaesthetics. FOS expression, which was examined postmortem, was decreased after the administration of local anaesthetics, except for bupivacaine. Based on these results, local anaesthesia decreases nociceptive transmission during piglet castration in this experimental setup. When combined with the corresponding haemodynamic parameters and the evaluation of defensive movements presented elsewhere, an overall understanding of the nociceptive response to castration can be generated. The objective of this study was to investigate the electroencephalographic reaction pattern and FOS protein expression in male piglets undergoing surgical castration under light isoflurane anaesthesia with or without local anaesthesia. The experiment was conducted under isoflurane anaesthesia to exclude the effect of the affective components of pain on the measurements. Changes in the oscillatory activity of the cerebral cortex over a 90 s period after noxious stimulation or simulated interventions were analysed. FOS expression was determined postmortem by performing immunohistochemistry in the dorsal horn of the spinal cord. The analysis of the response to an interdigital pinch revealed a biphasic reaction pattern in the electroencephalogram (EEG) that similarly was observed for the surgical stimuli during the castration procedure in the group without analgesia. This EEG response was attenuated or altered by the application of local anaesthetics. Immunohistochemical staining for FOS indicated a lower expression in the handling and in three local anaesthetic groups than in the animals castrated without pain relief. The findings indicate that EEG and FOS expression may serve as indicators for nociception in piglets under light isoflurane anaesthesia. A lower activation of nociceptive pathways occurs during castration after the application of local anaesthetics. However, EEG and FOS analyses should be combined with additional parameters to assess nociception, e.g., haemodynamic monitoring.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Tiermedizin > Veterinärwissenschaftliches Department
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• ISSN: 2076-2615
• Sprache: Englisch