Disruption of temporo-entorhinal connections abolishes recognition memory-enhancing effect of angiotensins in rats.
In our laboratory, the positive influence of angiotensin II and its 3-7 fragment on learning and memory processes was found to be mediated by excitatory amino acids, because it was abolished by N-methyl-D-aspartate (NMDA) receptor antagonists. The purpose of the present study was to investigate whether bilateral disruption of glutamatergic temporo-entorhinal connections may have an influence on the facilitatory effect of both angiotensin peptides on recognition memory. The bilateral transections of temporo-entorhinal connections were made in 32 male rats 10 days before testing the effect of intracerebroventricular AII or AII(3-7) injection on the recognition of objects evaluated in an object-recognition test. Thirty additional rats served as sham-operated controls. The final analysis was based on 29 lesioned and 26 sham-operated animals. AII and its 3-7 fragment significantly improved object recognition in the sham-operated groups of rats. Bilateral disruption of temporo-entorhinal connections totally abolished the facilitatory effect of both angiotensins on object recognition. Moreover, bilateral disruption of temporo-entorhinal connections significantly attenuated crossings of squares and rearings, without affecting bar approaches and defecation evaluated in an open-field test. These results may suggest that the facilitatory recognition memory effect of AII and AII(3-7) requires a reciprocal glutamatergic connection between the lateral entorhinal cortex and the temporal cortex.
Winnicka
M M
MM
Department of Pharmacology, Medical Academy of Bialystok, Poland.
Wiśniewski
K
K
D000804:Angiotensin II / Q000494:pharmacology; D000809:Angiotensins / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D018728:Entorhinal Cortex / Q000601:surgery*; D007276:Injections, Intraventricular; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology*; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D010446:Peptide Fragments / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013702:Temporal Lobe / Q000601:surgery*
D000809:Angiotensins; D010446:Peptide Fragments; D000804:Angiotensin II; C069545:angiotensin II (3-7)