Regulation of ER stress proteins, such as the 78-kilodalton glucose regulated protein (GRP78) by chronic treatment with mood stabilizing drugs suggests that this family of proteins may be involved in the pathophysiology of mood disorders. Indeed, increased levels of GRP78, GRP94, and calreticulin, a third member of the ERCurrent theories of the pathophysiology of mood disorders suggest that prolonged increases in glucocorticoid levels, likely the result of prolonged environmental stress, lead to biochemical changes in cortical and limbic neurons that leave individuals vulnerable to depression (Duman et al. 1997). A number of studies have found evidence of neuronal atrophy and loss of hippocampal neurons in response to stress (Magarinos et al. 1996;Uno et al. 1989;Sapolsky et al. 1985), and a report of reduced hippocampal volumes in elderly patients with histories of depression suggests that analogous processes may occur in individuals with depression (Sheline et al. 1996). Some models of mood disorders (Hyman and Nestler 1996; Post 1992) have attempted to incorporate the notion of compensatory processes into an understanding of the pathophysiologic changes that occur in patients with mood disorders, but few studies have tested these notions empirically (Post 1992). Part of the difficulty has been identifying neuroprotective mechanisms that may be of relevance for mood disorders.Recently, we found that treatment with the mood stabilizing drugs, valproate and carbamazepine, increased expression of the 78-kilodalton glucose-regulated protein (GRP78) . GRP78 is a member of the ER stress protein family that includes GRP94 and calreticulin, all of which function as Ca 2 ϩ binding proteins and molecular chaperones to assist in the regulation of protein folding (Gething 1997). These proteins have neuroprotective properties, are induced by seizures and ischemic damage, and may be involved in Alzheimer's disease pathology (Yu et al. 1999;Lowenstein et al. 1994;Hamos et al. 1991).Increased expression of ER stress proteins by mood stabilizing drugs suggest that these proteins may be in- METHODS Postmortem brain tissue was obtained from the StanleyFoundation Neuropathology Consortium (4 groups of n ϭ 15 age-and sex-matched subjects, i.e., subjects with bipolar disorder (BD), subjects with Major Depressive Disorder (MDD), subjects with schizophrenia (SCZ), and non-psychiatric, non-neurologic comparison subjects) (Johnston et al. 1997). Details on dissection and clinical characteristics have been previously published (Dowlatshahi et al. 1998(Dowlatshahi et al. , 1999. Briefly, all medical records for psychiatric cases were reviewed by two psychiatrists. Diagnosis was determined according to DSM-IV criteria. If there was disagreement about the diagnosis, a third psychiatrist read the records. If a diagnosis could not be established, a family member was then interviewed. All interviewed relatives were first degree except for two (one aunt and one father-in-law). Similarly, a clinical interview was performed with a family member...

Recent studies suggest that protein kinase C (PKC), particularly the α isoform, plays an important role in the action of lithium. There is, however, little evidence from patients with bipolar disorder (BD) to support this effect. The present investigation carried out comparative studies of PKC levels in platelets obtained from BD subjects including those with and without lithium treatment. All subjects met DSM-IV criteria for BD type I confirmed by structured interview (SCID-IV). Levels of PKC-α isoform in platelets from controls and from BD subjects were measured with immunoblotting analysis. No significant differences were found between controls, drug-free or lithium-treated BD subjects on membrane or cytosolic levels of PKC-α or in the membrane-to-cytosol ratio of this protein. The present study suggests that levels of PKC-α do not change in the peripheral tissues of BD subjects with or without lithium treatment.