Naltrexone modulates growth in infant rats

Life Sci. 1983 Dec 12;33(24):2449-54. doi: 10.1016/0024-3205(83)90639-2.

Abstract

Naltrexone, a potent opiate antagonist, had both stimulatory and inhibitory effects on somatic growth in preweaning rats depending on dose. Daily injections of 50 mg/kg naltrexone, which blocked morphine-induced analgesia for 24 hr/day, resulted in increased body and organ weights, and acceleration in the appearance of physical characteristics and maturation of spontaneous motor activity. Naltrexone in a dosage of 1 mg/kg, which blocked morphine-induced analgesia for 4 hr/day, had the opposite effects. These results show that naltrexone can modulate growth, and suggest a role for the endorphins and opiate receptors in developmental events.

MeSH terms

  • Animals
  • Animals, Newborn / growth & development
  • Body Weight / drug effects
  • Ear, External / drug effects
  • Eye / drug effects
  • Female
  • Growth / drug effects*
  • Hair / drug effects
  • Male
  • Motor Activity / drug effects
  • Naloxone / analogs & derivatives*
  • Naltrexone / pharmacology*
  • Organ Size / drug effects
  • Rats
  • Receptors, Opioid / drug effects
  • Receptors, Opioid / physiology*

Substances

  • Receptors, Opioid
  • Naloxone
  • Naltrexone