title: Inhibitory inputs to four types of spinocerebellar tract neurons in the cat spinal cord.
abstract: Spinocerebellar tract neurons are inhibited by various sources of input via pathways activated by descending tracts as well as peripheral afferents. Inhibition may be used to modulate transmission of excitatory information forwarded to the cerebellum. However it may also provide information on the degree of inhibition of motoneurons and on the operation of inhibitory premotor neurons. Our aim was to extend previous comparisons of morphological substrates of excitation of spinocerebellar neurons to inhibitory input. Contacts formed by inhibitory axon terminals were characterised as either GABAergic, glycinergic or both GABAergic/glycinergic by using antibodies against vesicular GABA transporter, glutamic acid decarboxylase and gephyrin. Quantitative analysis revealed the presence of much higher proportions of inhibitory contacts when compared with excitatory contacts on spinal border (SB) neurons. However similar proportions of inhibitory and excitatory contacts were associated with ventral spinocerebellar tract (VSCT) and dorsal spinocerebellar tract neurons located in Clarke's column (ccDSCT) and the dorsal horn (dhDSCT). In all of the cells, the majority of inhibitory terminals were glycinergic. The density of contacts was higher on somata and proximal versus distal dendrites of SB and VSCT neurons but more evenly distributed in ccDSCT and dhDSCT neurons. Variations in the density and distribution of inhibitory contacts found in this study may reflect differences in information on inhibitory processes forwarded by subtypes of spinocerebellar tract neurons to the cerebellum.
authors.affiliation: Spinal Cord Group, Institute of Neuroscience and Psychology, College of Medicine, Veterinary Medicine and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: S
authors.initials: S
authors.lastname: Shakya Shrestha
authors.forename: B A
authors.initials: BA
authors.lastname: Bannatyne
authors.forename: E
authors.initials: E
authors.lastname: Jankowska
authors.forename: I
authors.initials: I
authors.lastname: Hammar
authors.forename: E
authors.initials: E
authors.lastname: Nilsson
authors.forename: D J
authors.initials: DJ
authors.lastname: Maxwell
mesh_terms: D000818:Animals; D002415:Cats; D004558:Electric Stimulation; D018698:Glutamic Acid / Q000502:physiology; D005998:Glycine / Q000502:physiology; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D009411:Nerve Endings / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D010525:Peripheral Nerves / Q000502:physiology; D013116:Spinal Cord / Q000502:physiology*; D020824:Spinocerebellar Tracts / Q000502:physiology*; D050598:Vesicular Glutamate Transport Protein 1 / Q000502:physiology; D050599:Vesicular Glutamate Transport Protein 2 / Q000502:physiology; D050495:Vesicular Inhibitory Amino Acid Transport Proteins / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000502:physiology
chemical_list: D050598:Vesicular Glutamate Transport Protein 1; D050599:Vesicular Glutamate Transport Protein 2; D050495:Vesicular Inhibitory Amino Acid Transport Proteins; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D005998:Glycine