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Early exposure of pregnant animals to morphine is known to
cause retardation in neurobiological development resulting in
learning and memory disabilities of offsprings.The present
study examined the density of brain mu-opioid and NMDA receptor
of offsprings during differential development both in untreated
and chronic morphine treated group.Female Sprague-Dawley rats
(12 weeks old) were given morphine via subcutaneous twice daily.
Dam rats initial administered morphine(2 mg/kg)twice a day for
7 days ,then began to mate.The dosage of morphine increased 1
mg/kg each week until parturition.After the newborns were born,
dam rats were treated with morphine by increasing dosage of 1mg/
kg every two weeks until 30th day.The rat pups of each litter
were sacrificed by decapitation on day of parturition(p0),5(
p5),14(p14),or30(p30) days postnatal.Mu-opioid receptor binding
assays were carried out in triplicate with [3H]-DAMGO,using an
excess of unlabelled DAMGO to determine the nonspecific binding.
NMDA receptor binding assays were carried out with [3H]-TCP in
the presence of glycine,NMDA ; and using excess of unlabelled
TCP to determine the nonspecific binding.Measures of affinity
and number of binding sites were obtained by using the curve-
fitting program "Ligand".In autoradiography study,[3H]-DAMGO or
[3H]-Glutamate were used to determine mu-opioid or NMDA
receptor total binding. Nonspecifiwas defined by the addition
of unlabelled DAMGO or Receptor binding Results were quantified.
These data demonstrate that mu-opioid receptors and NMDA
receptors in the brain of offsprings during develpment are
affected by chronic treatment of morphine in dam.
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