Activin A and follistatin expression in developing targets of ciliary ganglion neurons suggests a role in regulating neurotransmitter phenotype.
The avian ciliary ganglion contains choroid neurons that innervate choroid vasculature and express somatostatin as well as ciliary neurons that innervate iris/ciliary body but do not express somatostatin. We have previously shown in culture that activin A induces somatostatin immunoreactivity in both neuron populations. We now show in vivo that both targets contain activin A; however, choroid expressed higher levels of activin A mRNA. In contrast, follistatin, an activin A inhibitor, was higher in iris/ciliary body. Iris cell-conditioned medium also contained an activity that inhibited activin A and could be depleted with anti-follistatin antibodies. These results suggest that development of somatostatin is limited to choroid neurons by differential expression of activin A and follistatin in ciliary ganglion targets.
Darland
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Department of Cell and Developmental Biology, Oregon Health Sciences University, Portland 97201, USA.
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Nishi
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D028341:Activins; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D002642:Chick Embryo; D002829:Choroid / Q000166:cytology / Q000378:metabolism; D017077:Culture Media, Conditioned; D038681:Follistatin; D005726:Ganglia, Parasympathetic / Q000196:embryology / Q000378:metabolism*; D015870:Gene Expression; D006023:Glycoproteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics*; D007124:Immunoenzyme Techniques; D007265:Inhibins / Q000032:analysis / Q000235:genetics*; D007498:Iris / Q000166:cytology / Q000378:metabolism; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism*; D010641:Phenotype; D013004:Somatostatin / Q000037:antagonists & inhibitors / Q000378:metabolism*
D017077:Culture Media, Conditioned; D038681:Follistatin; D006023:Glycoproteins; D028341:Activins; D013004:Somatostatin; D007265:Inhibins