Letter | Published:

Influence of Cocarboxylase on Tolerance to Morphine in the Rat


THE basic physiological mechanism affected by morphine may be that of the enzymatic processes involved in glucose metabolism: it is known, indeed, that morphine inhibits glucose and pyruvic acid utilization by minced brain1, and the decarboxylation by rabbit's liver and brain homogenates of pyruvic acid2. Further, morphine is known to reduce the level of carbon-14 in brains of rats fed with labelled glucose3. Cocarboxylase activity is unaffected in chronically morphinized rats, but responses to pyruvate and Cocarboxylase of in vitro muscle from animals deficient in thiamine and from chronically morphinized ones are similar, suggesting a metabolic defect in common to both conditions4; thiamine has no effect on morphine withdrawal symptoms in man5, though it decreases their intensity in rats6. Lastly, glycids and their metabolites change the analgesic effect of morphine.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

    Quastel, J. H., and Weatley, M. H., Proc. Roy. Soc., B, 112, 60 (1932).

  2. 2

    Santarato, R., Boll. Soc. Ital. Biol. Sper., 29, 626, 628, 630 (1953).

  3. 3

    Achor, L. B., and Geiling, E. M. K., Arch. Int. Pharmacodyn., 105, 313 (1956).

  4. 4

    Shideman, F. E., and Seevers, M. H., J. Pharmacol., 71, 383 (1941).

  5. 5

    Himmelsbach, C. K., J. Pharmacol., 70, 293 (1940). Himmelsbach, C. K., and Andrews, H. L., ibid., 77, 17 (1943).

  6. 6

    Fitzhugh, J. Pharmacol., 67, 423 (1939).

  7. 7

    Winter, C. A., and Flataker, L., J. Pharmacol., 98, 305 (1950).

  8. 8

    Di Mattei, P., “Attualità in tema di vitaminologia” (Cesalpino, 1942); “Questioni di attualità mediche e chirurgiche” (Pozzi, 1949); La Riforma Medica, 65, 430 (1951); Atti Convegno sulle Vitamine, C.N.R. (1953).

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.