The formalin test in the naked mole-rat (Heterocephalus glaber): analgesic effects of morphine, nefopam and paracetamol.
The present experiments were initiated to study the effects of morphine, nefopam and paracetamol in the naked mole-rat, a hairless rodent that lives in subterranean colonies of up to 300, following the inability to demonstrate morphine analgesia in the hot-plate test in the rodent. The formalin test was used. Injection of 20 microliters 10% formalin produced two periods of high licking and pain behaviour, the early (0-5 min) and the late phase (15-60 min). Morphine (10 or 20 mg/kg), nefopam (10 or 20 mg/kg) and paracetamol (200 mg/kg) significantly inhibited the two phases. Paracetamol (400 mg/kg) produced significant analgesia only during the late phase. It is concluded that, unlike in the hot-plate test, it is possible to demonstrate the analgesic effects of morphine in the naked mole-rat, in the formalin test.
Kanui
T I
TI
Department of Animal Physiology, University of Nairobi, Kenya.
Karim
F
F
Towett
P K
PK
D000082:Acetaminophen / Q000494:pharmacology*; D000700:Analgesics / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005557:Formaldehyde; D009020:Morphine / Q000494:pharmacology*; D009340:Nefopam / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology; D010146:Pain / Q000188:drug therapy / Q000503:physiopathology*; D012377:Rodentia
D000700:Analgesics; D005557:Formaldehyde; D000082:Acetaminophen; D009340:Nefopam; D009020:Morphine