A novel cyclic nucleotide-gated ion channel enriched in synaptic terminals of isotocin neurons in zebrafish brain and pituitary

S. Khan, C. Perry, M. L. Tetreault, D. Henry, James Trimmer, A. L. Zimmerman, G. Matthews

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Cyclic nucleotide-gated (CNG) channels are nonselective cation channels opened by binding of intracellular cyclic GMP or cyclic AMP. CNG channels mediate sensory transduction in the rods and cones of the retina and in olfactory sensory neurons, but in addition, CNG channels are also expressed elsewhere in the CNS, where their physiological roles have not yet been well defined. Besides the CNG channel subtypes that mediate vision and olfaction, zebrafish has an additional subtype, CNGA5, which is expressed almost exclusively in the brain. We have generated CNGA5-specific monoclonal antibodies, which we use here to show that immunoreactivity for CNGA5 channels is highly enriched in synaptic terminals of a discrete set of neurons that project to a subregion of the pituitary, as well as diffusely in the brain and spinal cord. Double labeling with a variety of antibodies against pituitary hormones revealed that CNGA5 is located in the terminals of neuroendocrine cells that secrete the nonapeptide hormone/transmitter isotocin in the neurohypophysis, brain, and spinal cord. Furthermore, we show that CNGA5 channels expressed in Xenopus oocytes are highly permeable to Ca2+, which suggests that the channels are capable of modulating isotocin release in the zebrafish brain and pituitary. Isotocin is the teleost homolog of the mammalian hormone oxytocin, and like oxytocin, it regulates reproductive and social behavior. Therefore, the high calcium permeability of CNGA5 channels and their strategic location in isotocin-secreting synaptic terminals suggest that activation of CNGA5 channels in response to cyclic nucleotide signaling may have wide-ranging neuroendocrine and behavioral effects.

Original languageEnglish (US)
Pages (from-to)79-89
Number of pages11
JournalNeuroscience
Volume165
Issue number1
DOIs
StatePublished - Jan 13 2010

Keywords

  • calcium entry
  • cyclic nucleotides
  • neuroendocrine cells
  • neurohypophysis
  • oxytocin
  • synaptic plasticity

ASJC Scopus subject areas

  • Neuroscience(all)

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