Nociceptin/orphanin FQ microinjected into hippocampus impairs spatial learning in rats.
The newly discovered peptide nociceptin/orphanin FQ has been found to increase reactivity to pain and to influence locomotor activity after intracerebroventricular administration. This study investigated the possible role of hippocampal nociceptin/orphanin FQ in spatial learning and in spontaneous locomotion. Male rats were trained in the Morris water task after microinjection of 10 nmol nociceptin/orphanin FQ or artificial cerebrospinal fluid (as control) into the CA3 region of the dorsal hippocampus. Nociceptin/orphanin FQ was found to severely impair spatial learning without interfering with swimming performance. Intrahippocampal injection of nociceptin/ orphanin FQ markedly decreased exploratory locomotor activity including vertical movements (rearing). The data suggest that nociceptin/orphanin FQ is a potent modulator of synaptic plasticity within the hippocampus.
Sandin
J
J
Department of Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden.
Georgieva
J
J
Schött
P A
PA
Ogren
S O
SO
Terenius
L
L
D000818:Animals; D006624:Hippocampus / Q000502:physiology*; D008124:Locomotion / Q000187:drug effects; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D008568:Memory / Q000187:drug effects; D008845:Microinjections; D009043:Motor Activity / Q000187:drug effects; D018847:Opioid Peptides / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011957:Receptors, Opioid / Q000819:agonists*; D000097629:Nociceptin
D018847:Opioid Peptides; D011957:Receptors, Opioid; D000097629:Nociceptin