Cyr, M Maclaren DA, Bédard M-A, Clark SD, Mechawar N, Rochford J, Winn P (2011) Highly selective lesion of the cholinergic pedunculopontine neurons using a minimally-invasive angular stereotaxic surgery with the Diphteria-Urotensin-II neurotoxin in rat. Neuroscience 2011 Abstracts 37.06. Society for Neuroscience, Washington, DC.
Summary: Highly selective cholinergic lesions of the basal forebrain can be achieved with the immunotoxin 192-IgG saporin. This toxin has no effect however on the cholinergic neurons of the pedunculopontine tegmental nucleus (PPTg). For many years, most studies have used excitotoxins such as ibotenate, quisqualate, kainate, or N-methyl-D-aspartate, with a relative efficacy in targeting the PPTg cholinergic neurons, however these toxins also destroy the interdigitated glutamatergic and GABAergic neurons. More recently, selective cholinergic lesions were obtained with the Dtx-UII neurotoxin in both rats (Clark et al., 2007) and monkeys (Karachi et al., 2010). This toxin binds at the Urotensin-II receptor predominantly expressed in the pedunculopontine and the laterodorsal, but not the basal forebrain cholinergic nuclei. Because of the scattered distribution of the cholinergic neurons in the rat PPTg, infusion of the Dtx-UII requires multiple skull holes and needle lowering through areas containing critical blood vessels, increasing therefore surgery time, incidence of bleeding and mortality rate. Here, we report that these disadvantages can be avoided by doing a single Dtx-UII infusion, through an angular stereotaxic pathway. Results were contrasted with those obtained from the classical flat skull stereotaxic surgery used by Clark et al. (2007). Long Evans rats (males 250g – 300g) were operated according to three different methods. In group one, 3μl of Dtx-UII (3% concentration) was infused evenly in three unilateral stereotaxic coordinates along the PPTg (pars oralis, centralis, caudalis), using a flat skull position. In groups two and three, 2μl and 3μl of Dtx-UII were infused respectively using the angular stereotaxic method described by Wishaw et al. (1977). Incisor bar was elevated such that there was an 8º29’ angle (.147) between the latter and the interaural line. Following rat sacrifices, ChAT and NeuN immunohistochemistry were conducted in order to determine the cholinergic specificity and magnitude of the lesions. Results revealed similar PPTg cholinergic lesions between the three groups, reaching > 80% on the side of the lesions. Group 1 showed the greatest non specific lesions outside the PPTg, attributable to the needle pathways. This group of rats also showed the greatest number of surgical complications. We conclude that the cholinergic PPTg neurons can be optimally lesioned by using an angular surgical approach with the Dtx-UII toxin. Clark S.D., et al. (2007). J Neurochem., 102, 112-120. Karashi C., et al. (2010). J Clinical Investigation, 120, 2745-2754. Wishaw et al. (1977). Physiol. Behav., 19, 719-722.
Related Products: 192-IgG-SAP (Cat. #IT-01)