Neurotransmitter phenotypes of descending systems in the rat lumbar spinal cord

Beau, A.D., Shrestha, S.S., Bannatyne, B.A., Jalicy, S.M., Linnen, S. and Maxwell, D.J. (2013) Neurotransmitter phenotypes of descending systems in the rat lumbar spinal cord. Neuroscience, 227, pp. 67-69. (doi: 10.1016/j.neuroscience.2012.09.037)

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Abstract

Descending systems from the brain exert a major influence over sensory and motor processes within the spinal cord. Although it is known that many descending systems have an excitatory effect on spinal neurons, there are still gaps in our knowledge regarding the transmitter phenotypes used by them. In this study we investigated transmitter phenotypes of axons in the corticospinal tract (CST); the rubrospinal tract (RST); the lateral component of the vestibulospinal tract (VST); and the reticulospinal tract (ReST). They were labelled anterogradely by stereotaxic injection of the b subunit of cholera toxin (CTb) in to the motor cortex, red nucleus, lateral vestibular nucleus and medial longitudinal fascicle to label CST, RST, VST and ReST axons respectively. Neurotransmitter content of labelled axons was investigated in lumbar segments by using immunofluroescence; antibodies against vesicular glutamate transporters (VGLUT1 and VGLUT2) were used to identify glutamatergic terminals and the vesicular GABA transporter (VGAT) was used to identify GABA- and glycinergic terminals. The results show that almost all CST (96%) axons contain VGLUT1 whereas almost all RST (97%) and VST (97%) axons contain VGLUT2. Although the majority of ReST axons contain VGLUT2 (59%), a sizable minority contain VGAT (20%) and most of these terminals can be subdivided into those that are GABAergic or those that are glycinergic because only limited evidence for co-localisation was found for the two transmitters. In addition, there is a population of ReST terminals that apparently does not contain markers for the transmitters tested and is not serotoninergic. We can conclude that the CST, RST and VST are 'pure' excitatory systems whereas the ReST consists of a heterogeneous population of excitatory and inhibitory axons. It is anticipated that this information will enable inputs to spinal networks to be defined with greater confidence.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Maxwell, Professor David
Authors: Beau, A.D., Shrestha, S.S., Bannatyne, B.A., Jalicy, S.M., Linnen, S., and Maxwell, D.J.
College/School:College of Medical Veterinary and Life Sciences > Institute of Neuroscience and Psychology
Journal Name:Neuroscience
ISSN:0306-4522
ISSN (Online):1873-7544
Published Online:24 September 2012

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
284171Spinal Interneurons: 5HT-NA receptors, actions, circuitsDavid MaxwellNational Institutes of Health (NIHBETH)UNSPECIFIEDRI NEUROSCIENCE & PSYCHOLOGY