ABSTRACT
This communication reports the effect of alphaxalone on motor somatosensory evoked potential (SEPs) in a rhesus macaque. The animal was deeply anaesthetised with an infusion of ketamine, medetomidine, midazolam and alfentanil. The median nerve was stimulated, and SEPs were recorded from the motor cortex. The successive administration of three doses of alphaxalone (0.5, 1 and 2 mg/kg) induced an increase of the latency time and a decrease of the amplitude of the SEPs. However, the structure of the waveforms was conserved, and hence alphaxalone might represent a suitable general anaesthetic option in neuroscience research as well as veterinary or human medicine.
Subject(s)
Motor Cortex , Pregnanediones , Animals , Electric Stimulation , Evoked Potentials, Somatosensory , Female , Humans , Macaca mulattaABSTRACT
BACKGROUND: The use of non-human primates (NHPs) in research remains a major societal concern with public expectations that appropriate anaesthetics and analgesics are used to minimize any pain or distress caused to animals undergoing invasive procedures. A literature review was conducted to examine the reporting of anaesthesia and analgesia methods used in non-human primates undergoing surgical procedures, with recovery from anaesthesia. METHODS: A total of 397 papers from peer-review journals published between 2010 and 2015 were examined. RESULTS: Only 25.9% of papers reported the analgesic regimen used, with carprofen and buprenorphine the 2 most widely used agents. Reporting of the anaesthetic regimens was included in 49.9% of papers. Ketamine and isoflurane were the most frequently used anaesthetic agents. CONCLUSIONS: Anaesthetic and analgesic regimens administered to NHPs remain poorly reported. This lack of detailed descriptions of protocols does little to reassure the public or regulatory authorities that appropriate high standards of perioperative care are employed.
ABSTRACT
The intrathecal (IT) route of administration represents a means to reduce the dose of morphine administered for analgesia, potentially minimizing interactions between opioid effects and experimental outcomes. Perceived technical difficulty, and previously described invasive methods, may limit its use. This report describes a minimally invasive technique for IT administration of morphine by direct transcutaneous lumbosacral puncture in rats; and assesses antinociceptive properties of morphine in anaesthetized rats. Rats ( n = 28) anaesthetized with sevoflurane (inspired fraction of sevoflurane: FiSevo = 2.4%) were randomly allocated to receive: IT morphine (0.2 mg/kg); subcutaneous (SC) morphine (3 mg/kg); SC buprenorphine (0.05 mg/kg); or SC or IT sodium chloride (NaCl). After a wash-in period (40 min), thermal nociceptive stimuli were applied at nine locations corresponding to different rostrocaudal dermatomes of the rat. Nociceptive stimulation cycles were repeated at all locations after successive decrement of FiSevo by 15%. Presence or absence of gross purposeful movement (GPM) was recorded for each individual stimulation. IT injection of morphine by direct puncture with a 25 G hypodermic needle is easily performed (successful first attempt: 82%) without complications. IT morphine reduced the frequency of GPM following nociceptive thermal stimulation in a way comparable with SC buprenorphine or morphine. It was not possible to delimit any rostral spinal spread of morphine. This report describes a refined and effective technique of administering morphine IT in rats using readily available materials. IT doses being markedly smaller than the systemic equivalent, analgesia could be provided whilst minimizing the potential interactions of non-analgesic opioid effects with research protocols.
