Document Type : Original Article
PHYSIOLOGY DEPARTMENT, SCHOOL OF MEDICAL SCIENCES,TARBIAT MODARRES UNIVERSITY,TEHRAN, IRAN
Introduction: The aim of this study was to evaluate the changes in cAMP and some other cellular ingredients following adenyl cyclase activation in paragigantocellularis (PGi) neurons of morphine dependent and withdrawn rats.
Material and methods: The 3.5 mm thick brainstem slice prepared from PGi area (-10.04 to -13.24 from bregma) of control and morphine dependent rats (n=5 in each group). Were treated by forskolin (50?M) and IBMX (500?M) bath. Then, tissue was extracted with perchloric acid and cAMP, ATP and phosphocreatine (PCr) were measured in the extract with 31p-NMR spectroscopy. Lactic acid, alanine, taurine, GABA, glutamate, glutamine and N-acetylaspartate were measured in the extract by 1H-NMR spectroscopy.
Results: 31p-NMR spectroscopy revealed an increase of cAMP content and concurrent decrease in ATP and PCr following forskolin and lBMX applications (p<0.05, t-test). 1H-NMR spectroscopy showed a reduction in both lactic acid and alanine contents in dependent group after same treatment (p<0.05, t-test). Other cellular ingredients were not changed. In the dependent rats, cAMP increased and concurrently ATP and PCr decreased following forskolin/lBMX applications (p<0.05, t-test). Lactic acid and alanine decreased in the dependent group after forskolin/lBMX treatment (p<0.05, t-test).
Conclusion: It is concluded that an increase in cAMP content results from enhancement of adenylyl cyclase activity and it is considered as one of the cellular basis of morphine dependence and withdrawal in PGi neurons. In addition, morphine dependence produces profound metabolic changes in PGi neurons.