Up-regulation of neuronal calcium sensor-1 (NCS-1) in the prefrontal cortex of schizophrenic and bipolar patients

Abstract

The delineation of dopamine dysfunction in the mentally ill has been a long-standing quest of biological psychiatry. The present study focuses on a recently recognized group of dopamine receptor-interacting proteins as possible novel sites of dysfunction in schizophrenic and bipolar patients. We demonstrate that the dorsolateral prefrontal cortex in schizophrenia and bipolar cases from the Stanley Foundation Neuropathology Consortium display significantly elevated levels of the D2 dopamine receptor desensitization regulatory protein, neuronal calcium sensor-1. These levels of neuronal calcium sensor-1 were not influenced by age, gender, hemisphere, cause of death, postmortem period, alcohol consumption, or antipsychotic and mood stabilizing medications. The present study supports the hypothesis that schizophrenia and bipolar disorder may be associated with abnormalities in dopamine receptor-interacting proteins.

Figure 1

Representative examples of the images of slot blots and Western blots generated in this study. (A) Typical fluorescent image of a membrane with slot blots stained for the total protein. (B) Film image of the same membrane resulted from NCS-1-specific immunolabeling. In both A and B, 1–12 are triplicate blots from different tissue samples. Six “standard” blots were made from the specially prepared human LDPFC homogenates with known amounts of the total protein. The background blots contain either pure homogenization buffer or BSA. (C) Typical film image produced by NCS-1 immunostaining of Western blot of human LDPFC. The image contains only a single band of ≈22 kDa, which is the molecular mass of NCS-1.

Figure 2

Plots of the levels of NCS-1 (expressed per nanogram of total protein and per nanogram of neuronal DNA) in the DLPFC from NC, SCHIZ, BPD, and MD groups of the Stanley Foundation Neuropathology Consortium. Each group in the consortium = 15 cases. Circles represent the data from individual samples. The horizontal lines represent the mean values for the group. Vertical lines represent SD. P = statistical significance of Dunnett's post hoc one-way ANOVA comparison of the levels of NCS-1 between NC and a given mental disease group (P for the ANOVAs preceding the Dunnett's tests: 0.007 for NCS-1 expressed per total protein and 0.001 for NCS-1 expressed per neuronal DNA). The statistically significant increases in NCS-1 levels (marked by asterisks) as compared with controls are seen in SCHIZ and BPD groups.

Figure 3

Histogram showing the DLPFC levels of NCS-1 in SCHIZ and BPD patients from the Stanley Foundation Neuropathology Consortium who at the time of death received either no medications, antipsychotic drugs, mood-stabilizing drugs, or a combination of these drugs. Each column represents the mean ± SD. No statistically significant differences are present (P of one-way ANOVA = 0.407). DF, drug free; AS, antipsychotic medication; MS, mood-stabilizing medications.

Figure 4

Plots of correlation analyses of the levels of NCS-1 in the DLPFC expressed per neuronal DNA in relation to age, postmortem period (PMI), brain pH, and the lifetime dosage of antipsychotic drugs in fluphenazine equivalents among the cases constituting the Stanley Foundation Neuropathology Consortium. Circles represent values for individual samples. R = correlation coefficient; P = significance. There are no significant correlations between NCS-1 levels and age, PMI, brain pH, and the lifetime dosage of antipsychotic drugs. In contrast, there is a significant negative correlation between the levels of NCS-1 and tissue alkalinity (indicated by the descending line and the asterisk near the appropriate P value).