The effect of naloxone and morphine on 3H-1-lysine in vivo incorporation into various neurons separated from fixed rat brain preparations by ultrasonification: a comparison of morphine effects between Wistar and Sprague-Dawley rats.

Abstract

A procedure is described where by ultrasonification one can separate large neurons from their surrounding neuropil from either unfixed brain and peripheral ganglion or from similar tissue fixed in 10 per cent neutral formalin for prolonged periods. The availability of such a technique permits one to readily assess the accumulation of 3H-labeled protein precursors into a wide variety of neurons, utilizing standard liquid scintillation techniques. The separation technique has been applied in this report to determine the effects of morphine, morphine plus naloxone, naloxone given alone and saline on the accumulation of 3H-1-lysine into ventral horn, Purkinje and dorsal root ganglion neurons in Sprague-Dawley rats. The data from the control and morphine-treated animals has then been compared with similar data previously obtained from Wistar rats. In Sprague-Dawley rats, morphine had no effect on 3H-1-lysine accumulation into ventral horn neurons and stimulated accumulation into Purkinje and dorsal root ganglion neurons. Naloxone stimulated lysine accumulation into dorsal root ganglion and ventral horn neurons, but had equivocal effects on Purkinje neuron 3H-lysine accumulation. When Wistar and Sprague-Dawley rats were compared, marked differences in the effect which morphine had on lysine accumulation into neurons were noted between the two strains of rat. Ventral horn and dorsal root ganglion neurons from Wistar rats had markedly higher levels of accumulation in both control and morphine-treated rats than were observed in the Sprague-Dawley animals. With Purkinje neurons, accumulation levels between the two strains overlapped each other. Morphine inhibited lysine accumulation in Wistar Purkinje neurons but stimulated it in the Sprague-Dawley animals. The profiles of the accumulation curves from two rat strains suggest that there are not only differences in rates of uptake of 3H-lysine into protein followed by degradation between various types of neurons, but differences between the two strains as well.