The effects of κ-opioid agonist treatment on κ-opioid receptor density and on dynorphin A levels in the rat brain were studied. Rats were treated with the selective κ-opioid agonist U-69593 or vehicle for 5 d. Dynorphin A levels and κ-opioid receptor binding were measured on day 8 (3 d after the last injection) or 22 (17 d after the last injection). On day 8, κ-opioid receptor density was increased in the hypothalamus of rats treated with U-69593; there were no changes in the frontal cortex or caudate putamen. In contrast, there was an increase in dynorphin A levels in the frontal cortex and no changes in hypothalamus and caudate putamen in response to U-69593. On day 22, Bmax was decreased in frontal cortex and caudate putamen of U-69593-treated rats, whereas dynorphin A levels were increased in the caudate putamen and in the frontal cortex. These findings suggest that κ-opioid receptor agonist treatment has long-term, continually changing effects on the κ-opioid system.
Differential time course of the effects of kappa-opioid agonist treatment on dynorphin A and on k-opioid receptor density / DADDARIO C.; DI BENEDETTO M.; IZENWASSER S.; CANDELETTI S.; ROMUALDI P.. - In: JOURNAL OF MOLECULAR NEUROSCIENCE. - ISSN 0895-8696. - STAMPA. - 24:(2004), pp. 321-328. [10.1385/JMN:24:2:307]
Differential time course of the effects of kappa-opioid agonist treatment on dynorphin A and on k-opioid receptor density
DI BENEDETTO, MANUELA;CANDELETTI, SANZIO;ROMUALDI, PATRIZIA
2004
Abstract
The effects of κ-opioid agonist treatment on κ-opioid receptor density and on dynorphin A levels in the rat brain were studied. Rats were treated with the selective κ-opioid agonist U-69593 or vehicle for 5 d. Dynorphin A levels and κ-opioid receptor binding were measured on day 8 (3 d after the last injection) or 22 (17 d after the last injection). On day 8, κ-opioid receptor density was increased in the hypothalamus of rats treated with U-69593; there were no changes in the frontal cortex or caudate putamen. In contrast, there was an increase in dynorphin A levels in the frontal cortex and no changes in hypothalamus and caudate putamen in response to U-69593. On day 22, Bmax was decreased in frontal cortex and caudate putamen of U-69593-treated rats, whereas dynorphin A levels were increased in the caudate putamen and in the frontal cortex. These findings suggest that κ-opioid receptor agonist treatment has long-term, continually changing effects on the κ-opioid system.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
