A study of the enzyme inducing effect of physical exercise after partial hepatectomy in the rat

Relationships among muscular exercise, enzyme induction and liver regeneration were studied. Exercized and control groups of rats showed no appreciable difference in liver regeneration rate expressed in liver weight increase. The enzyme-inducing effect of muscular exercise manifested itself also in the regenerating liver. The shortening of hexobarbital sleeping time occurred earlier in the group which had been trained already before partial hepatectomy than in the other group in which exercise training started only after the intervention. This was explained by a higher physical working capacity achieved by previous training, which was retained also after partial hepatectomy. This finding provides further indirect support for the relationship between enhanced biotransformation rate and muscular exercise, the latter being the agent in the induction process.

The effects of lesion of mesolimbic dopamine neurons on pain threshold and morphine analgesia in rats

Lesions of ventral tegmental area, localised in the region of A 10 group of dopaminergic mesolimbic neurons decreased the pain threshold in rats. The absolute threshold values in morphine treated animals with the above lesion were lower than in sham-operated controls, however, the thresholds expressed as percentage of predrug threshold values did not differ in both lesioned and sham-operated animals. It is thought, that lesions of ventral tegmental dopamine neurons decrease the pain threshold due to the increase of general excitability of animals, and that there is no direct involvement of the lesioned structure in the primary mechanism of morphine analgesia.