Localization of opioid receptors in the central nervous system and assessment of morphine and butorphanol analgesic and sedative effects in green iguanas (Iguana iguana)

Author(s)

Thais Feres Bressan

• Document type: Doctoral Thesis
• Press: Pirassununga.
• Institution: Universidade de São Paulo (USP). Faculdade de Zootecnica e Engenharia de Alimentos (FZE/BT)
• Defense date: 2017-12-15

Examining board members

Adriano Bonfim Carregaro; Silvia Renata Gaido Cortopassi; Cléo Alcantara Costa Leite; Daniele dos Santos Martins; Ricardo de Francisco Strefezzi

• Advisor: Adriano Bonfim Carregaro; Heidge Fukumasu

Abstract

The increasing popularity of reptiles in the pet market and in the scientific studies requires appropriate clinical and physiological knowledge, which will consequently improve the quality of care and management of this classe. It is necessary to have studies with each species in particular because of every specie of reptile has different metabolic and physiological behavior. Therefore, it was aimed localization of opioid receptor in the central nervous system (CNS) and evaluated the sedative and analgesic effect of morphine and butorphanol in Iguana iguana. At the first stage three young (101 ± 6g) and healthy green iguanas were submitted to euthanasia for harvesting the CNS, then the tissues of two animals were submitted to the RNAseq technique for the formation of de Novo transcriptome, so we could get the nucleotide sequences of the opioid receptors obtained. The immunohistochemistry (IH) technique was use to locate the distribution of these receptors in the CNS. In the second stage, 10 young green iguanas (160 ± 46 g) received five treatments, intramuscularly and with an interval of two weeks between them: saline solution (0.3 mL, CON), morphine 5 mg/kg (MOR5) and 10 mg/kg (MOR10), butorphanol 5 mg/kg (BUT5) and 10 mg/kg (BUT10). The sedation was estimate by behavioral scale for iguanas and forced swing test, during 120 seconds. The latency of hind limb withdrawal reflex (LWR) in front of the thermal stimulus was use for antinociceptive evaluation promoted by opioids. All the tests were evaluate before treatment (0) and at 30 minutes, 1, 2, 3, 4, 6, 12 and 24 hours post-treatment. ANOVA and Dunnett were used for comparison with the baseline (0 minute) and two-way ANOVA and Tukey between the groups. We identified sequences compatible with μ (mu), κ (kappa) and δ (delta), but only κ and δ were marked in the IH of the CNS. In the behavior scale despite of low scores of sedation, it was observe a significant increase in the score between 30 minutes and 2 hour MOR5 and between 30 minutes and 3 hours in MOR10, BUT5 and BUT10. The time of swimming test was reduced in MOR10 and BUT5 between 30 minutes and 2 hours and in BUT10 the reduction occurred between 30 minutes and 12 hours. All treatment provided sedation for both tests in 12 hours of evaluation. Otherwise, the thermoalgymetry test showed increased time in LWR in MOR10 between 2 hours and 4 hours of evaluation. It concluded that the opioid receptors are present in the CNS. In addition, the two doses of butorphanol and the highest dose of morphine further sedation and only 10 mg/kg of morphine promoted antinociception in iguanas in this study. (AU)

• FAPESP's process: 14/09529-7 - Characterization of opioid receptors in the central nervous system and evaluation of analgesic and sedative effects of opioids in green iguanas (Iguana iguana)
• Grantee: Thais Feres Bressan
• Support Opportunities: Scholarships in Brazil - Doctorate