European Neuropsychopharmacology 10 (2000) 337–340 www.elsevier.com / locate / euroneuro Lymphocyte peripheral benzodiazepine receptor mRNA decreases in obsessive-compulsive disorder a, a b c a * Paola Rocca , Anna Maria Beoni , Carola Eva , Patrizia Ferrero , Giuseppe Maina , a a Filippo Bogetto , Luigi Ravizza a Department of Neuroscience, Section of Psychiatry, University of Turin, via Cherasco 11, 10126 Torino, Italy b Section of Pharmacology, Department of Anatomy, Pharmacology and Forensic Medicine, via P .Giuria 13, 10125 Torino, Italy c Section of Neurology, University of Turin, via Cherasco 15, 10126 Torino, Italy Received 27 January 2000; accepted 2 May 2000 Abstract The relative content of peripheral benzodiazepine receptor (pBR) mRNA was examined by reverse transcriptase-polymerase chain reaction in lymphocytes of obsessive-compulsive disorder (OCD) patients, according to their clinical course of illness. pBR mRNA significantly decreased only in chronic OCD patients ( n58) as compared to controls ( n510), whereas no significant changes were observed in episodic OCD patients ( n57). We suggest that modulation of pBR gene expression might delineate a clinical heterogeneity in OCD.  2000 Elsevier Science B.V. All rights reserved. Keywords: Peripheral benzodiazepine receptor mRNA; Obsessive-compulsive disorder; Anxiety disorders; Clinical subtypes 1. Introduction Weizman et al., 1993; Marazziti et al., 1994; Gavish et al., 1996; Johnson et al., 1998). Peripheral benzodiazepine receptors (pBR) are 18-kDa We previously found a decreased number of lymphocyte proteins pharmacologically and structurally distinct from pBR in OCD (Rocca et al., 1991). In contrast two later central benzodiazepine receptors. pBR are found in almost reports demonstrated that the density of platelet pBR is all tissues and are highly expressed on mitochondrial unchanged in OCD patients as compared to healthy membranes of steroid-producing cells where they regulate controls (Weizman et al., 1993; Marazziti et al., 1994). the rate-limiting step in steroidogenesis. Much evidence The discrepancy among these studies may be related to the suggests that pBR are involved in the regulation of stress clinical heterogeneity in the OCD patients. Several studies responses. pBR increase the production of stress-reactive suggest that OCD represents a heterogeneous condition, or hormones such as corticosterone in response to systemic group of related syndromes, with overlapping but separate stress. Acute stress increases and chronic stress reduces biological and psychological abnormalities (Rasmussen pBR density in several tissues (Drugan, 1996). Further- and Eisen, 1992). On the basis of the clinical course, we more, lymphocyte and platelet pBR are lowered in some, identified two clinical subtypes of the disorder — episodic but not all, of the anxiety disorders (Gavish et al., 1992; and chronic OCD — with significant differences in demo- graphic and symptomatological features (Ravizza et al., 1997). We previously showed that pBR density decreases only in the OCD patients who presented a chronic, *Corresponding author. Tel.: 139-11-663-4848; fax: 139-11-673-473. E-mail address: milani@molinette.unito.it (P. Rocca). progressive clinical course (Rocca et al., 1991). The 0924-977X / 00 / $ – see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S0924-977X(00)00091-2