Injections of an opioid antagonist into the locus coeruleus and periaqueductal gray but not the amygdala precipitates morphine withdrawal in the 7-day-old rat

Synapse. 2001 Feb;39(2):139-51. doi: 10.1002/1098-2396(200102)39:2<139::AID-SYN5>3.0.CO;2-#.

Abstract

Opiate withdrawal behaviors in the infant differ from those of the adult. The neural circuitry underlying opioid withdrawal in the adult rat is well defined and includes the locus coeruleus (LC) and periaqueductal gray (PAG), with a minor role of the amygdala. Because the different behaviors that constitute the infant syndrome may be mediated by different neural circuits, we tested the hypothesis that these three sites are involved in opiate withdrawal. Pups were injected with morphine from day 1-6 after birth (b.i.d.) and on the morning of the seventh day. Withdrawal was then elicited by local injection of the opioid antagonist methylnaloxonium into the LC, PAG, or amygdala. Withdrawal signs were precipitated in a dose-dependent manner following injection into the LC or PAG, but not the amygdala. The withdrawal behaviors elicited from the LC and PAG included both the same and different behaviors. The results support the hypothesis that the neural circuitry mediating opiate withdrawal behaviors is similar in infant and adult animals, but the behaviors expressed are age-specific.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Age Factors
  • Amygdala / drug effects*
  • Amygdala / growth & development
  • Amygdala / physiopathology
  • Animals
  • Animals, Newborn
  • Behavior, Animal / drug effects
  • Behavior, Animal / physiology
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Female
  • Locus Coeruleus / drug effects*
  • Locus Coeruleus / growth & development
  • Locus Coeruleus / physiopathology
  • Male
  • Morphine / pharmacology*
  • Naloxone / analogs & derivatives*
  • Naloxone / pharmacology
  • Naltrexone / pharmacology
  • Narcotic Antagonists / pharmacology*
  • Neural Pathways / drug effects
  • Neural Pathways / growth & development
  • Neural Pathways / physiopathology
  • Opioid-Related Disorders / pathology
  • Opioid-Related Disorders / physiopathology*
  • Periaqueductal Gray / drug effects*
  • Periaqueductal Gray / growth & development
  • Periaqueductal Gray / physiopathology
  • Quaternary Ammonium Compounds
  • Rats
  • Rats, Long-Evans
  • Substance Withdrawal Syndrome / etiology
  • Substance Withdrawal Syndrome / pathology
  • Substance Withdrawal Syndrome / physiopathology*

Substances

  • Narcotic Antagonists
  • Quaternary Ammonium Compounds
  • Naloxone
  • Naltrexone
  • N-methylnaloxone
  • Morphine