Nuno M Félix - Centro de Investigação Interdisciplinar em Sanidade Animal (CIISA) Faculdade de Medicina Veterinária, University of Lisbon (ULisboa), Lisboa, Portugal
Rodolfo O Leal - Centre Hospitalier Vétérinaire Fregis, Arcueil, France
I Goy-Thollot - SIAMU, VetAgro Sup, Marcy l’Étoile, France – Université de Lyon, VetAgro Sup, EA APCSe Agressions Pulmonaires et Circulatoires dans le Sepsis, Marcy L’Etoile, France
Ronald S Walton - Animal Medical Center of Seattle Shoreline, Washington, USA
Solange A Gil - Centro de Investigação Interdisciplinar em Sanidade Animal (CIISA) Faculdade de Medicina Veterinária, University of Lisbon (ULisboa), Lisboa, Portugal
Luísa M Mateus - Centro de Investigação Interdisciplinar em Sanidade Animal (CIISA) Faculdade de Medicina Veterinária, University of Lisbon (ULisboa), Lisboa, Portugal
Ana S Matos - UNIDEMI, Departamento de Engenharia Mecânica e Industrial, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
Maria M R E Niza - Centro de Investigação Interdisciplinar em Sanidade Animal (CIISA) Faculdade de Medicina Veterinária, University of Lisbon (ULisboa), Lisboa, Portugal

Objective(s): Buprenorphine is a common analgesic in experimental research, due to effectiveness and having few side-effects, including a limited influence in the immune and endocrine systems. However, how buprenorphine affects cytokine levels and the adrenal and thyroid response during general anesthesia and surgery is incompletely understood. This study aimed to assess whether buprenorphine modulated significantly those responses in rats submitted to general anesthesia, mechanical ventilation, and surgical insertion of intravascular catheters. Materials and Methods: Animals were anesthetized with isoflurane, mechanically ventilated, and surgically instrumented for carotid artery and the femoral vein catheter placement. The test group (n=۱۶), received buprenorphine subcutaneously before surgery, whereas the control group (n=۱۶) received normal saline. Blood sampling to determine plasma levels of adrenocorticotropic hormone (ACTH), corticosterone (CS), total thyroxine (TT۴), total triiodothyronine (TT۳), thyroid-stimulating hormone (TSH), TNF-α, IL۶, IL۱۰, TNF-α, IL۶, and IL۱۰ mRNA was performed at ۱۰ min after completion of all surgical procedures and at ۹۰, ۱۵۰, ۲۴۰, and ۳۰۰ min thereafter, with the animals still anesthetized and with mechanical ventilation. Results: Buprenorphine-treated animals had higher levels of ACTH, CS, and TT۴ at several time points (P<۰.۰۵) and TSH and TT۳ at all-time points (P<۰.۰۵). They also had increased IL۱۰, TNF-α, and IL۱۰ mRNA levels. Conclusion: In this model, buprenorphine significantly modulated the intra-operative cytokine and endocrine response to anesthesia, mechanical ventilation, and surgical placement of intravascular catheters. The mechanism and significance of these findings remain undetermined. Researchers should be aware of these effects when considering the use of buprenorphine for analgesic purposes.

ACTH, Buprenorphine, Corticosterone, Cytokine, Intra- surgery, Rat