| Abstract: | Experiments on cats were made to examine the neuronal responses (the first zone of the somatosensory cortex and the 5th region of the parietal associative cortex) to microapplications of beta-neo-endorphine (an agonist of kappa-opiate receptors), morphine (an agonist of mu-opiate receptors), leuenkephalin (an agonist of delta-opiate receptors) and beta-endorphine (an agonist of mu, delta, epsilon-opiate receptors). beta-Neo-endorphine and other opioid peptides produced similar depressive changes in spontaneous activity. Naloxone in doses which block the depressive reactions of morphine, leu-enkephalin and beta-endorphine did not remove the depressive reactions of beta-neo-endorphine. Opioid peptides and morphine produced different changes in nociceptive-stimulated neuronal activity in the first zone of the somatosensory cortex and photostimulated neuronal activity in the 5th region of the parietal cortex. It is assumed that the different types of opiate receptors and their endogenous ligands (opioid peptides) play different functional roles in the preparation of the nociceptive and visual information in the cortex. |
