Protein kinase C redistribution within CA3 stratum oriens during acquisition of nictitating membrane conditioning in the rabbit.

Abstract

This manuscript describes experiments designed to investigate protein kinase C redistribution occurring during acquisition of the rabbit nictitating membrane (NM) conditioned response (CR). The first experiment defined the acquisition phase of the NM response for our laboratory. A group of rabbits (n = 6) was given 2 days of paired NM training; a second group (n = 6) was given 2 days of unpaired NM training. The data document a variable level of responding on day 1 for rabbits given paired training (mean ± SEM, 21 ± 11% CRs) but show that on day 2 most rabbits reached the behavioral asymptote (five of six rabbits responding with >85% CRs). Rabbits responding at the behavioral asymptote were defined as having acquired the NM conditioned response. These data were interpreted to indicate that 1 day of training initiated processes necessary for behavioral acquisition (i.e., responding at the behavioral asymptote). A quantitative finm autoradiographic study of [3H]phorbol 12,13-dibutyrate binding was then used to determine the distribution of hippocampal protein kinase C in rabbits sacrificed after receiving either 1 day ofpaired stimuli (n = 10), 1 day of unpaired stimuli (n = 6), or no stimuli (n = 6). Autoradiograms were analyzed by measuring binding in strictly defined regions of interest and from transept profiles. A significant increase in binding of the phorbol ester was found in the CA3 stratum oriens in the paired group relative to unpaired and naive controls. No other significant differences were found.The nictitating membrane (NM) conditioned response (CR) is an associative learning model in which rabbits learn to associate a tone (conditioned stimulus, CS) with a shock (unconditioned stimulus, US) to the periorbital region (1, 2). Retraction of the NM in response to the tone (a CR) is used to index the progression of learning. The hippocampus has been shown to be necessary for both proper consolidation of the NM response in undertrained rabbits and proper extinction of the response in overtrained rabbits (3, 4). Firing patterns for CA1 and CA3 pyramidal cells formed a striking "neural model" of the CR during paired NM training (5). Furthermore, changes in neuronal firing within the CA1 and CA3 areas of the hippocampus occurred within the first 10 paired trials and increased throughout the training period (5, 6).Extensive studies of hippocampal neurons have been performed with rabbits that were overtrained using this paradigm and sacrificed 24 hr later. In such rabbits, postsynaptic biophysical changes in CA1 neurons were demonstrated, including increased input resistance (7), decreased after hyperpolarizations (8, 9), and increased summation of postsynaptic potentials (10). Accompanying the biophysical changes at this time point were biochemical changes (11-13), with two studies localizing an increase in membrane-bound protein kinase C (mPKC) to the CAl region (11, 12). Binding of phorbol 12,13-dibutyrate (PBt2) in brain of overtrained rabbits sacrificed 72 hr after completion of training showed P...

Amygdala kindling‐induced seizures selectively impair spatial memory. 1. Behavioral characteristics and effects on hippocampal neuronal protein kinase C isoforms

“…Additional evidence about the preand postsynaptic localization should be obtained by electron microscopic studies. Our findings generally agree well with several previous reports in which other learning and memory paradigms were used, assigning a potential role of PKC in long-term regulation of cell memory (Bank et al, 1988;Olds et al, 1989;Scharenberg et al, 1991). In these latter studies an increase in activated PKC is first detected in CA1 pyramidal cell somata and followed by a redistribution to the dendrites.…”

Protein and Molecular Characterization of Hippocampal Protein Kinase C in C57BL/6 and DBA/2 Mice

“…Recently, several studies have demonstrated that changes in hippocampal PKC occur in response to several phases of learning, including the acquisition, conditioning, and retention phases (Bank et al ., 1988 ;Olds et al ., 1989Olds et al ., , 1990Scharenberg et al ., 1991 ;Sunayashiki-Kusuzaki et al, 1993) . The results of the present study indicate that not only does PKC change as a result of learning, but inherent differences in PKC may underlie good or poor learning abilities .…”

?isoform-selective changes in PKC immunoreactivity after trace eyeblink conditioning in the rabbit hippocampus

“…Initial studies (for a historical review, see Van der Zee and Douma, 1997) used the tritiated phorbol ester 12,13-dibutyrate ([ 3 H]PDBu) to probe PKC and to localize the changes (Bank et al, 1988;Olds et al, 1989Olds et al, , 1990Olds and Alkon, 1991;Scharenberg et al, 1991;Golski et al, 1995). However, [ 3 H]PDBu has some important limitations: its specificity as a PKC probe has been questioned (Wilkinson and Hallam, 1994); it lacks isoform selectivity (Hug and Sarre, 1993;Dimitrijevic et al, 1995); and it has a relatively limited spatial resolution.…”

“…Ample evidence in the last decade has demonstrated the involvement of PKC in learning and memory processes and long-term potentiation (LTP) (Akers et al, 1986;Bank et al, 1988;Olds et al, 1989Olds et al, , 1990Wehner et al, 1990;Olds and Alkon, 1991;Scharenberg et al, 1991;Mathis et al, 1992;Paylor et al, 1992;Lucchi et al, 1993;Sacktor et al, 1993;Sunayashiki-Kusuzaki et al, 1993;Noguès et al, 1994;Golski et al, 1995). Initial studies (for a historical review, see Van der Zee and Douma, 1997) used the tritiated phorbol ester 12,13-dibutyrate ([ 3 H]PDBu) to probe PKC and to localize the changes (Bank et al, 1988;Olds et al, 1989Olds et al, , 1990Olds and Alkon, 1991;Scharenberg et al, 1991;Golski et al, 1995).…”