Journal of Neuroscience, Vol 13, 2749-2757, Copyright © 1993 by Society for Neuroscience
Adult-type glycine receptors form clusters on embryonic rat spinal cord neurons developing in vitro
PA St John and SL Stephens
Department of Anatomy, University of Arizona College of Medicine, Tucson 85724.
The time course of development and the cellular and subcellular
distributions of adult-type, strychnine-binding glycine receptors (GlyRs)
were examined on rat spinal cord neurons in vitro using both the GlyR
antagonist strychnine and a specific antibody against the receptor. Spinal
cord neurons in vivo had no detectable adult-type GlyRs at embryonic day
14, the age used to establish cell cultures. After being placed in culture,
neurons continued for several days to show no expression of adult-type
GlyRs. This contrasted with the observation that these neurons began to
express receptors for substance P within 24 hr in culture. Beginning after
5-7 d in culture, however, neurons began to express adult-type GlyRs on
their surfaces, and the number of such receptors increased abruptly
thereafter. Ultimately, about 80% of the neurons in heterogeneous spinal
cord cultures came to express adult-type GlyRs, with all of them beginning
to express the GlyRs at approximately the same time. The subcellular
distribution of adult-type GlyRs on neurons was observed by fluorescence
microscopy using both anti-GlyR antibody and a fluorescent derivative of
strychnine. On neurons that had been in culture for more than 10 d, GlyRs
were localized in focal clusters, or aggregates, that were distributed over
both cell bodies and neurites. The apparent location of these clusters on
the cell surface was confirmed by the observation that GlyRs could be
labeled with the antibody on living neurons.(ABSTRACT TRUNCATED AT 250
WORDS)