Regular Article
Effects of Posttraining Treatments in the Posterior Cingulate Cortex on Short- and Long-Term Memory for Inhibitory Avoidance in Rats

https://doi.org/10.1006/nlme.2001.4009Get rights and content

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-μl infusion of vehicle (phosphate-buffered saline, pH 7.4), of the GABAA receptor agonist muscimol (0.1 or 0.5 μg), of the cAMP-dependent protein kinase (PKA) stimulant Sp-cAMPS (0.1 or 0.5 μg), or of the PKA inhibitor Rp-cAMPS (0.1 or 0.5 μg). 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 μg) hindered retention for both short- and long-term memory (p < .05). Rp-cAMPS (0.1 or 0.5 μg) 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 μg (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.

References (31)

  • T. Mello e Souza et al.

    Involvement of the medial precentral prefrontal cortex in memory consolidation for inhibitory avoidance learning in rats

    Pharmacology, Biochemistry and Behavior

    (2000)
  • M.F. Bear et al.

    Neuroscience: Exploring the Brain

    (1995)
  • T.V.P. Bliss et al.

    A synaptic model of memory: Long-term potentiation in the hippocampus

    Nature

    (1993)
  • B. Bontempi et al.

    Time-dependent reorganization of brain circuitry underlying long-term memory storage

    Nature

    (1999)
  • V.S. Caviness et al.

    Tangential organization of thalamic projections to the neocortex in the mouse

    Journal of Comparative Neurology

    (1981)
  • Cited by (20)

    • Unraveling Molecular and System Processes for Fear Memory

      2022, Neuroscience
      Citation Excerpt :

      Later, the same laboratory replicated this amnesic effect and also found that RSC PKA activity inhibition hinders STM and, perhaps, LTM, a tentative conclusion because of scores variance. Interestingly, the muscimol amnesic effect on STM was more robust and easier to verify (Souza et al., 2002). Izquierdo and associates also showed that, in the RSC, adenosine A1 receptors inhibit memory consolidation so that their blockade facilitates IA memory (Pereira et al., 2002b), and the ectonucleotidase pathway responds to a mild footshock (Pereira et al., 2002a).

    • Individual Subnuclei of the Rat Anterior Thalamic Nuclei Differently affect Spatial Memory and Passive Avoidance Tasks

      2020, Neuroscience
      Citation Excerpt :

      One possibility is that the AV nucleus affects consolidation of the PA task via its extensive reciprocal connections with the ACC and retrosplenial cortex (PCC) (van Groen and Wyss, 1990; Shibata and Naito, 2005; Wright et al., 2010) or through its afferents from the prelimbic cortex (Wright et al., 2013). Involvement of the PCC and ACC has been proved in processing information related to consolidation phase of the PA task (Mello e Souza et al., 1999; Souza et al., 2002). It has been shown that stimulation of GABAergic synapses and inhibition of glutamatergic synapses via inactivation of NMDA receptors in the retrosplenial cortex causes disturbances in the PA consolidation (Mello e Souza et al., 1999).

    • Taraxerol as a possible therapeutic agent on memory impairments and Alzheimer's disease: Effects against scopolamine and streptozotocin-induced cognitive dysfunctions

      2018, Steroids
      Citation Excerpt :

      Also, TRX could affect pro- or anti-conflict behaviors, and to considering that, the animals were submitted to the elevated plus-maze test. The animals were allowed to explore the apparatus which consists in two opened arms (50 × 10 cm3), two closed arms (50 × 10 × 15 cm3) and a central area (10 × 10 cm3) 70 cm elevated from floor, which is used to measure anxiety behavior of animals [32]. After 5 min of intra-hippocampal administration of the TRX (1.77 µM/side, 0.5 µL) or vehicle, each animal was placed on the center of the apparatus, facing one of the enclosed arms.

    • Protective effects of anthocyanins on the ectonucleotidase activity in the impairment of memory induced by scopolamine in adult rats

      2012, Life Sciences
      Citation Excerpt :

      Furthermore, our results showed that 5′-nucleotidase and ADA activities seem to be more sensitive in the HC than CC, so we believe that ectonucleotidase in the hippocampus is more affected by scopolamine (see Figs. 3 and 4). However, we can not exclude that specific regions of the cerebral cortex which are known to participate in memory formation, as the posterior cingulate and entorhinal cortex (Lima et al., 2009; Pereira et al., 2005, 2001; Souza et al., 2002), are also affected by SCO administration, so ectonucleotidase activities were measured in the whole cerebral cortex and not in specific regions, might have been the reason that no significant differences were observed in this brain structure. The activity of this enzyme is very important because this leads to production of extracellular adenosine (Burnstock, 2006a, b; Robson et al., 2006; Schetinger et al., 2001).

    View all citing articles on Scopus

    This study was supported by Conselho Nacional de Pesquisa (CNPq) and PRONEX, Brazil. We are grateful to Beatriz Aparecida de Almeida Moleta for her contribution to the present work.

    f2

    Address correspondence and reprint requests to T. Mello e Souza, Centro de Memória, Departamento de Bioquimica, Instituto de Ciências Bāsicas de Saúde, Universidade Federal do Rio Grande do Sul (UFRGS), Ramiro Barcelos 2600, 90035-003 Porto Alegre, RS, Brazil. Fax: 5551 3165535. E-mail: [email protected].

    View full text