title: Principalis- or parabrachial-projecting spinal trigeminal neurons do not stain for GABA or GAD.
abstract: Retrograde transport and immunohistochemical double-labeling methods (Weinberg et al., 1985) were used to assess the distribution and projection status of spinal trigeminal (SpV) neurons that stain positively for glutamic acid decarboxylase (GAD) or gamma-aminobutyric acid (GABA). Large bilateral injections of diamidino yellow into the rostral and lateral pons, inclusive of V nucleus principalis and the parabrachial nucleus, retrogradely labeled large numbers of cells in each SpV subnucleus. Many cells in SpV subnuclei caudalis, interpolaris, and oralis also exhibited GABA immunoreactivity; the largest numbers were in caudalis and the smallest numbers were in oralis. However, none of the GABA- or GAD-immunoreactive SpV cells were double-labeled with diamidino yellow, though some reticular neurons displayed both GABA and the retrograde tracer. This negative result refutes a previously offered hypothesis that SpV local-circuit neurons with principalis collaterals are GABA-ergic (Jacquin et al., 1989b). These data also indicate that parabrachial-projecting SpV neurons are not GABA-ergic.
authors.affiliation: Department of Anatomy and Neurobiology, St. Louis University School of Medicine, Missouri 63104.
authors.forename: J H
authors.initials: JH
authors.lastname: Haring
authors.forename: T A
authors.initials: TA
authors.lastname: Henderson
authors.forename: M F
authors.initials: MF
authors.lastname: Jacquin
mesh_terms: D000818:Animals; D001917:Brachial Plexus / Q000033:anatomy & histology*; D001933:Brain Stem / Q000033:anatomy & histology; D005260:Female; D005455:Fluorescent Antibody Technique; D005968:Glutamate Decarboxylase / Q000378:metabolism*; D008297:Male; D008465:Mechanoreceptors / Q000033:anatomy & histology*; D009415:Nerve Net / Q000033:anatomy & histology*; D009474:Neurons / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D009435:Synaptic Transmission / Q000502:physiology*; D014278:Trigeminal Nuclei / Q000033:anatomy & histology; D014279:Trigeminal Nucleus, Spinal / Q000033:anatomy & histology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase