Avtor/Urednik		Kolaj, M; Černe, R; Randić, M
Naslov		The opioid peptide dynorphin modulates AMPA and kainate responses in acutely isolated neurons from the dorsal horn
Tip		članek
Vir		Brain Res
Vol. in št.		Letnik 671, št. 2
Leto izdaje		1995
Obseg		str. 227-44
Jezik		eng
Abstrakt		In freshly isolated spinal dorsal horn (DH) neurons (laminae I-IV) of the young rat, the effects of dynorphin A1-17, U-50,488H and U-69,593 on inward currents induced by alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainate (KA) were studied under whole-cell voltage-clamp conditions. When the cells were clamped to a holding potential of -60 mV, co-application of dynorphin A1-17 (10(-6) M) and AMPA (2 x 10(-5) M) reversibly decreased the peak amplitude of the initial transient component of the AMPA-induced current in 72 percent of the examined cells. In addition, dynorphin (10 microM) in perforated patch-recordings consistently produced a decrease in the steady-state component of the AMPA response. The depressant effect was concentration-dependent (IC50 = 86 nM) and reversible. The dynorphin A1-17-induced depression of the AMPA response was associated with slowing of the response kinetics, including both a 10-90 percent rise-time and time constant of decay. The AMPA-induced currents were modulated by dynorphin not only during the co-administration but also after the removal of the peptide. Dynorphin increased the initial peak AMPA current in 42 percent of the examined cells. Similar as with dynorphin A1-17, the peak amplitude of the AMPA-induced current was reversibly suppressed in the presence of 1 microM U-50,488H and U-69,593 in 75 percent and 86 percent of the examined cells, respectively. Naloxone and the kappa 1-selective antagonist norbinaltorphimine (nor-BNI) blocked the initial depressant but not late excitatory effects of dynorphin A1-17 and U-50,488H. This antagonistic effect of naloxone and norbinaltorphimine suggests that the depressant effect of dynorphin A1-17 on the AMPA-activated conductance is a true opioid, probably kappa 1-opioid receptor-mediated event.(trunc.)
Deskriptorji		DYNORPHINS NEURONS RECEPTORS, AMPA RECEPTORS, KAINIC ACID SPINAL CORD ALPHA-AMINO-3-HYDROXY-5-METHYL-4-ISOXAZOLEPROPIONIC ACID AI ANTAGONISTS AND INHIBITORS PD PHARMACOLOGY CYCLIC AMP-DEPENDENT PROTEIN KINASES PATCH-CLAMP TECHNIQUES PERTUSSIS TOXINS RATS RATS, SPRAGUE-DAWLEY RECEPTORS, OPIOID, KAPPA SPINAL CORD