Description:
<jats:p>
In the brains of rats without tolerance to morphine, the accumulation of [
<jats:sup>14</jats:sup>
C]dopamine formed from [
<jats:sup>14</jats:sup>
C]tyrosine injected intracisternally is increased, reaching a maximum in the hypothalamus and striatum 1 hour after administration of morphine. In tolerant rats, the rate of incorporation of carbon-14 into dopamine and into norepinephrine in these areas is more than twice that in animals that have received only one injection of morphine.
</jats:p>