Decreased ( 3H) quinuclidinyl benzilate binding to lymphocytes in Gilles de la Tourette syndrome

Abstract

In spite of an unknown pathophysiology, it has been suggested that central dopaminergic hyperactivity exists in Gilles de la Tourette syndrome (TS). Cholinergic influences have also been postulated as a dopaminergic-cholinergic balance seems to be important in other movement disorders. If TS is due to alterations of cholinergic activity, this may also be expressed at postsynaptic levels. Recently, we showed that circulating lymphocytes may serve as useful peripheral markers reflecting induced alterations or inherent changes in muscarinic receptors in the central nervous system (CNS). In the present study, we compared the muscarinic binding characteristics in peripheral lymphocytes as measured by ( 3H) quinuclidinyl benzilate ([( 3H)-QNB] in 27 umedicated TS patients, against 22 healthy (age and gender-matched) controls. B max and K d values were determined using Lineweaver-Burke plots. The mean B max values in nontreated TS patients was markedly and significantly lower than in controls (10.59 ± 8.4 versus 40.16 ± 9.2 fmole/10 6 cells, p < 10 −6), while K d values were similar in both groups. Our findings suggest that changes in cholinergic receptors may play a role in the pathophysiology of Tourette syndrome.