Antipsychotic medication and oxidative cell stress: a systematic review

OBJECTIVE

To look at (1) the association between antipsychotics and cell stress, (2) whether first-generation antipsychotics may show different effects than second-generation antipsychotics, and (3) whether recommendations can be made regarding medication.

DATA SOURCES

We conducted a systematic review of 5 databases for all articles published until December 31, 2007: PubMed, Ovid MEDLINE, EMBASE, PsycINFO, and EBM Reviews. Under specific headings (eg, "heat shock proteins" and "oxidative stress"), a systematic search of these databases included such terms as HSP70 and homocysteine, and specific search strings were constructed. No limits were placed on the year or language of publication. References from pertinent articles or books were retrieved.

STUDY SELECTION

We included 42 articles of human studies from 2,387 references originally retrieved. We included only articles that (1) were quantitative; (2) referred only to human tissue, in vivo, or in vitro; (3) stated what tissue was examined; (4) identified what metabolites were measured; and (5) had references.

DATA EXTRACTION

All articles were assessed by 2 authors, which ensured that the inclusion criteria were met. The selected studies were too heterogeneous to be combined for any useful meta-analysis. Three authors, therefore, independently interpreted the data, using specified criteria to judge whether each study showed a beneficial, detrimental, or no effect on the markers measured.

DATA SYNTHESIS

The analysis revealed no conclusive association with direct or indirect markers of oxidative cell stress and antipsychotics. For every reviewed antipsychotic, we revealed differing research results showing a beneficial, detrimental, or no effect. This was true for in vivo as well as in vitro studies.

CONCLUSIONS

It remains unclear whether antipsychotics increase or reduce cell stress. Claims of neuroprotective properties of antipsychotics seem premature.

Birth defects and anti-heat shock protein 70 antibodies in early pregnancy

Abstract It has been suggested that induction of the heat shock response in the mammalian embryo during the critical period of organogenesis can result in anatomical malformation. We measured serum heat shock protein 70 (Hsp70), anti-Hsp70, and anti-Hsp60 in samples taken from expectant mothers at 16 weeks gestation. Samples from women whose babies were born with a birth defect (n = 30) were compared with controls who gave birth to healthy babies (n = 46). Anti-Hsp70 levels were significantly elevated in patients who later gave birth to babies with cleft lip or palate or neurological abnormalities (n = 10): 260 (223-406) microg/mL compared to 150 (88-207) microg/mL in controls (P < 0.001). No significant differences were found in serum Hsp70 and anti-Hsp60 levels between cases and controls. This finding of increased maternal anti-Hsp70 in patients who later gave birth to babies with these abnormalities suggests a previous stressful event may have contributed to the pathogenesis. Further work is required to determine whether Hsp70 has a direct or indirect role in this pathogenesis or whether anti-Hsp70 is simply a marker of a prior increase in Hsp70 due to a physiological stress that itself resulted in the damage. This work is consistent with previous studies showing a buffering role for Hsps in evolution.

Folate supplementation reduces serum hsp70 levels in patients with type 2 diabetes

Type 2 diabetes patients are subject to oxidative stress as a result of hyperglycemia. The aim of this study was to determine whether administration of the antioxidant folic acid, previously shown to reduce homocysteine levels, would reduce circulating levels of Hsp70 while improving the condition of type 2 diabetes patients with microalbuminuria. Plasma homocysteine fell from pretreatment values of 12.9 to 10.3 microM (P < 0.0001). The urine albumin-creatinine ratio fell from 12.4 to 10.4 mg/mM (P = 0.38). Pretreatment Hsp70 levels were higher in patients not taking insulin (5.32 ng/mL) compared with those on insulin (2.44 ng/mL) (P = 0.012). Folic acid supplementation resulted in a significant fall in Hsp70 (5.32 to 2.05 ng/mL) (P = 0.004). There was no change in Hsp70 in those receiving insulin. Folic acid supplementation in non-insulin-treated type 2 diabetes patients, therefore, resulted in a fall in Hsp70, reflecting an improvement in oxidative stress. The data shows that improvement in homocysteine status can lead to a reduction in Hsp70, indicating the possibility of its use as a marker for severity of disease.

Hsp70 release from peripheral blood mononuclear cells

There are an increasing number of studies reporting the presence of Hsps in human serum. We have investigated the release of Hsp70 into blood and culture medium from peripheral blood mononuclear cells (PBMCs), and whether this release is due to cell damage or active secretion from the cells. Intact Hsp70 was released from cells within whole blood and from purified PBMCs under normal culture conditions. Hsp70 release was rapid (0.1 ng/10(6) cells/h) over the first 2 h of culture and continued at a reduced rate up to 24 h (<0.025 ng/10(6) cells/h). Using viable cell counts and lactate dehydrogenase release we were able to confirm that the release of Hsp70 was not due to cellular damage. Hsp70 release was inhibited by monensin, methyl-beta-cyclodextrin, and methylamine, but not by brefeldin A. These data suggest that Hsp70 is released from cells via a non-classical pathway, possibly involving lysosomal lipid rafts.