Changes in NOS protein expression and activity in the rat hippocampus, entorhinal and postrhinal cortices after unilateral electrolytic perirhinal cortex lesions.
The integrity of the perirhinal cortex is critical for certain types of learning and memory. One important issue relating to the function of this region is its interaction with other brain areas that play a role in memory processing. This study investigates the time course of changes in activity and protein expression of nitric oxide synthase (NOS), which transforms L-arginine into nitric oxide (NO) and citrulline, in the hippocampus and the entorhinal and postrhinal cortices after unilateral electrolytic lesions of the perirhinal cortex. Electrolytic lesions of the perirhinal cortex resulted in long lasting changes in NOS activity and protein expression in the entorhinal and postrhinal cortices (< or = 2 weeks post-lesion). In contrast, there was a small and transient decrease in nNOS expression (with no change in NOS activity) in the dorsal portion of the hippocampus. iNOS was not expressed in any region examined at any time point. These findings provide the first evidence that electrolytic lesions of the perirhinal cortex can result in long-term neurochemical changes in its anatomically related structures. Given that NO has been implicated in neuroplasticity processes, the interpretation of memory impairments induced by electrolytic lesions of the perirhinal cortex (and possibly, therefore, other brain regions) need to be considered with regard to these findings.
Liu
Ping
P
Department of Psychology and the Neuroscience Research Centre, University of Otago, Dunedin, New Zealand. ping.liu@stonebow.otago.ac.nz
Zheng
Yiwen
Y
Smith
Paul F
PF
Bilkey
David K
DK
D000818:Animals; D003714:Denervation; D015536:Down-Regulation / Q000502:physiology; D018728:Entorhinal Cortex / Q000201:enzymology* / Q000503:physiopathology; D006624:Hippocampus / Q000201:enzymology* / Q000503:physiopathology; D008297:Male; D008569:Memory Disorders / Q000201:enzymology* / Q000503:physiopathology; D009434:Neural Pathways / Q000201:enzymology* / Q000293:injuries / Q000503:physiopathology; D009473:Neuronal Plasticity / Q000502:physiology; D009474:Neurons / Q000201:enzymology; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D020534:Parahippocampal Gyrus / Q000201:enzymology* / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000502:physiology
D009569:Nitric Oxide; D019001:Nitric Oxide Synthase