Somatostatin triggers rhythmic electrical firing in hypothalamic GHRH neurons

Research output: Contribution to journalArticle

Authors

  • Guillaume Osterstock
  • Violeta Mitutsova
  • Alexander Barre
  • Manon Granier
  • Pierre Fontanaud
  • Marine Chazalon
  • Danielle Carmignac
  • Iain Robinson
  • Malcolm Low
  • Nikolaus Plesnila
  • Patrice Mollard
  • Pierre-Francois Mery

Colleges, School and Institutes

External organisations

  • Inserm U-1191, Montpellier, France
  • MRC National Institute for Medical Research
  • Dept of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA
  • Royal College of Surgeons in Ireland, Dublin 2, Ireland

Abstract

Hypothalamic growth hormone-releasing hormone (GHRH) neurons orchestrate body growth/maturation and have been implicated in feeding responses and ageing. However, the electrical patterns that dictate GHRH neuron functions have remained elusive. Since the inhibitory neuropeptide somatostatin (SST) is considered to be a primary oscillator of the GH axis, we examined its acute effects on GHRH neurons in brain slices from male and female GHRH-GFP mice. At the cellular level, SST irregularly suppressed GHRH neuron electrical activity, leading to slow oscillations at the population level. This resulted from an initial inhibitory action at the GHRH neuron level via K+ channel activation, followed by a delayed, sst1/sst2 receptor-dependent unbalancing of glutamatergic and GABAergic synaptic inputs. The oscillation patterns induced by SST were sexually dimorphic, and could be explained by differential actions of SST on both GABAergic and glutamatergic currents. Thus, a tripartite neuronal circuit involving a fast hyperpolarization and a dual regulation of synaptic inputs appeared sufficient in pacing the activity of the GHRH neuronal population. These “feed forward loops” may represent basic building blocks involved in the regulation of GHRH release and its downstream sexual specific functions.

Details

Original languageEnglish
Article number24394
JournalScientific Reports
Volume6
Publication statusPublished - 13 Apr 2016

Keywords

  • Metabolism, Arcuate nucleus, GHRH, GABA, glutamate, somatostatin