Regulation of Ca²⁺/Calmodulin-Dependent Protein Kinase II Signaling within Hippocampal Glutamatergic Postsynapses during Flurazepam Withdrawal

Figure 1

Images of asymmetric synapses in the CA1 SR of control (a) and 2-day FZP-withdrawn (b) rats colabeled with anti-CaMKIIα (1 : 20, recognized with 15 nm gold, arrows) and anti-pCaMKII antibodies (1 : 10, recognized with 10 nm gold, arrowheads). CaMKII and pCaMKII immunogold particles were observed pre- and postsynaptically, both intracellularly and associated with the membrane and PSD. Scale bar = 0.2 μm. (c) There was no significant change in the percent of boutons, spines, or PSDs labeled with either CaMKII or pCaMKII (𝑃>0.05 in each case). (d) There was a nonsignificant decrease in CaMKII labeling in spines (CON: 1.41±0.36 particles, 𝑛=5; FZP: 0.86±0.17 particles, 𝑛=5; 𝑃=0.20), as well as decreased CaMKII immunogold particles/PSD length (CON: 2.88±0.97 particles/μm, 𝑛=5; FZP: 1.10±0.29 particles/μm, 𝑛=5; 𝑃=0.12). However, without an alteration in pCaMKII labeling there was no change in the pCaMKII/CaMKII ratio in PSDs of 2-day FZP-withdrawn rats (CON: 1.14±0.48, 𝑛=5; FZP: 2.52±0.64, 𝑛=5; 𝑃=0.12). (e) Analysis of immunopositive compartments (≥1 immunogold particle) revealed a significant decrease in CaMKII labeling in immunopositive spines (CON: 2.77±0.22 particles, 𝑛=5; FZP: 1.94±0.23 particles, 𝑛=5; 𝑃=0.03) and PSDs (CON: 9.77±0.92 particles/μm; FZP: 6.88±0.37 particles/μm; 𝑃=0.02) from 2-day FZP-withdrawn rats. However, the ratio of pCaMKII/CaMKII within the PSD was not significantly altered (CON: 1.01±0.19, 𝑛=5; FZP: 1.35±0.09, 𝑛=5; 𝑃=0.14).