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
by
Jones KL, Barr GA
Biopsychology Doctoral Program,
City University of New York,
Psychology Department,
Hunter College,
City University of New York,
New York.
Synapse 2001 Feb; 39(2):139-151

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.

Pain
Lofexidine
Oxycodone
Endomorphins
Novelty and pain
Fentanyl and ketamine
Signalling mechanisms
The extended amygdala
Opioids, mood and cognition
Tolerance, sensitization and dependence
Alpha-2 adrenergic agonists for opioid withdrawal

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