title: Effects of posttraining treatments in the posterior cingulate cortex on short- and long-term memory for inhibitory avoidance in rats.
abstract: Adult male Wistar rats were bilaterally implanted with indwelling cannulae in the caudal region of the posterior cingulate cortex. After recovery, animals were trained in a step-down inhibitory avoidance task (3.0-s, 0.4-mA foot shock) and received, right after training, a 0.5-microl infusion of vehicle (phosphate-buffered saline, pH 7.4), of the GABA(A) receptor agonist muscimol (0.1 or 0.5 microg), of the cAMP-dependent protein kinase (PKA) stimulant Sp-cAMPS (0.1 or 0.5 microg), or of the PKA inhibitor Rp-cAMPS (0.1 or 0.5 microg). Animals were tested twice, 1.5 h and, again, 24 h after training, in order to examine the effects of these agents on short- and long-term memory, respectively. Muscimol (0.5 but not 0.1 microg) hindered retention for both short- and long-term memory (p <.05). Rp-cAMPS (0.1 or 0.5 microg) hindered retention for short-term memory (p <.05). In addition, these animals showed lower, but not significantly lower, latencies than controls in the test session for long-term memory (p >.10). A trend toward an amnesic effect on long-term memory was also observed after Sp-cAMPS infusion at 0.1 microg (p <.10). These results show that strong stimulation of GABAergic synapses in the caudal region of the rat posterior cingulate cortex right after training impairs short- and long-term memory (the latter less dramatically). The same occurs by inhibiting PKA activity with regard to STM and possibly to LTM.
authors.affiliation: Centro de Memória, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Ramiro Barcelos 2600, 90035-003 Porto Alegre, RS, Brazil. msouza@vortex.ufrgs.br
authors.forename: M M
authors.initials: MM
authors.lastname: Souza
authors.forename: T
authors.initials: T
authors.lastname: Mello e Souza
authors.forename: E R
authors.initials: ER
authors.lastname: Vinadé
authors.forename: C
authors.initials: C
authors.lastname: Rodrigues
authors.forename: H K
authors.initials: HK
authors.lastname: Choi
authors.forename: T L
authors.initials: TL
authors.lastname: Dedavid e Silva
authors.forename: J H
authors.initials: JH
authors.lastname: Medina
authors.forename: I
authors.initials: I
authors.lastname: Izquierdo
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018755:GABA Agonists / Q000494:pharmacology; D006179:Gyrus Cinguli / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008568:Memory / Q000187:drug effects*; D008570:Memory, Short-Term / Q000187:drug effects; D017551:Microdialysis; D009118:Muscimol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D011963:Receptors, GABA-A / Q000187:drug effects; D012153:Retention, Psychology / Q000187:drug effects; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D018755:GABA Agonists; D011963:Receptors, GABA-A; D013873:Thionucleotides; C016957:adenosine-3',5'-cyclic phosphorothioate; D009118:Muscimol; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases