Influence of buprenorphine analgesia on post-operative recovery in two strains of rats

Abstract

SummaryT he objective of this study was to establi sh an effective post-operati ve analgesic regim en for Sprague-Dawley (SD ) and Dark Agouti (DA) rats. Buprenorphine (0.01 or 0.05 mg=kg), a partial m opioid agonist, was administered subcutaneously immediately on completion of a standardized surgical procedure, involving anaesthesia, laparotom y and visceral manipulation. Two of the four treatm ent groups and the saline control group received a second injection 9 h later. Behavioural observations by three independent observers provided no information in assessing pain in this model. All rats lost weight, consumed less food and water after surgery. On the ®rst day, both SD and DA rats receiving buprenorphine lost less weight than untreated control groups. Using weight loss as an ef®cacy criterion, low-dose buprenorphine, given once or twice, provided effective analgesia in SD rats. A higher single dose provided no additional bene®t and a second dose was detrimental, reducing body weight and food intake. In DA rats, the high dose, given twice, appeared to be more effective than the lower dose. All DA cage cohorts consumed <10 % pre-operative food despite buprenorphine treatm ent, suggesting a higher dosage may be necessary. However, all SD and 80 % DA rats who received no buprenorphine gained body weight on the second day, whereas most of the buprenorphine-treated rat s continued to lose weight for another 2 days, despite increased food consumption by both strains. Buprenorphine may adversely affec t intestinal function over a number of days due to its enterohepatic circulation; this effect may be more severe in DA rats. Adverse metabolic effects of buprenorphine and other opioids may preclude their use in the future if it can be shown that non-steroidal anti-in¯am matory drugs (NSAIDs) provide equally effective analgesia.

Correlation between body weight changes and postoperative pain in rats treated with meloxicam or buprenorphine

“…Evaluation of pain in the ubiquitous laboratory rodent is especially challenging. Several studies suggest that clinical parameters such as change in body weight and daily oral fluid intake correlate with postoperative pain in rodents 1–4. Although such parameters provide appropriate indications of rodent well-being during routine clinical care and maintenance, these objective measurements fail to account for typical factors operant during the postoperative period, such as the effect of narcotic analgesic medications on volition and the physiologic stress response to surgery.…”

“…In several studies, weight loss in adult animals and alterations in normal growth rates in young animals have been used as indicators of postoperative pain 1–4,13. None of those studies, however, distinguished between weight alterations caused by postoperative pain and those caused by physiologic effects of anesthesia or analgesic drugs.…”

Effect of Subcutaneous Injection and Oral Voluntary Ingestion of Buprenorphine on Post-Operative Serum Corticosterone Levels in Male Rats

“…Buprenorphine is more potent than morphine in rats [15] but reaches a plateau in analgesic effect due to its agonist-antagonistic properties [18] . Buprenorphine has been shown to alleviate pain in both analgesiometric tests and clinical trials, and due to its potent analgesic effects it has been widely used for laboratory animals for more than 2 decades [19] .…”

Preanesthesia, Anesthesia, Analgesia, and Euthanasia

“…While lower doses are not associated with significant side effects, in the rat, pica and possibly long-term weight reductions have been reported at higher doses or with prolonged dosing schedules ( (Schaap et al, 2012;Bomzon, 2006). Strain and sex of rodents can also modulate response to opiates (Jablonski et al, 2001;Avsaroglu et al, 2007Avsaroglu et al, , 2008Cotroneo et al, 2012;Wright-Williams et al, 2013). Although usually given as an injection, in some studies orally administered buprenorphine was efficacious in alleviating postoperative pain, however, its utility may be limited in duration of analgesia and by reliable consumption of the food stuffs or water into which it is compounded (Flecknell et al, 1999a;Martin et al, 2001;Jablonski and Howden, 2002;Thompson et al, 2004Thompson et al, , 2006Jessen et al, 2007;Goldkuhl et al, 2010a,b;Leach et al, 2010b;Kalliokoski et al, 2011;Abelson et al, 2012).…”