Electrophysiological evidence for vasopressin V1 receptors on neonatal motoneurons, premotor and other ventral horn neurons

Murat Oz, Miloslav Kolaj, Leo P. Renaud

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

Prominent arginine-vasopressin (AVP) binding and AVP V1 type receptors are expressed early in the developing rat spinal cord. We sought to characterize their influence on neural excitability by using patch-clamp techniques to record AVP-induced responses from a population of motoneurons and interneurons in neonatal (5-18 days) rat spinal cord slices. Data were obtained from 58 thoracolumbar (T7-L5) motoneurons and 166 local interneurons. A majority (>90%) of neurons responded to bath applied AVP (10 nM to 3μM) and (Phe2, Orn8)-vasotocin, a V1 receptor agonist, but not V2 or oxytocin receptor agonists. In voltage-clamp, postsynaptic responses in motoneurons were characterized by slowly rising, prolonged (7-10 min) and tetrodotoxin-resistant inward currents associated with a 25% reduction in a membrane potassium conductance that reversed near -100 mV. In interneurons, net AVP-induced inward currents displayed three patterns: decreasing membrane conductance with reversal near -100 mV, i.e., similar to that in motoneurons (24 cells); increasing conductance with reversal near -40 mV (21 cells); small reduction in conductance with no reversal within the current range tested (41 cells). A presynaptic component recorded in most neurons was evident as an increase in the frequency but not amplitude (in motoneurons) of inhibitory and excitatory postsynaptic currents (IPSCs and EPSCs), in large part due to AVP-induced firing in inhibitory (mainly glycinergic) and excitatory (glutamatergic) neurons synapsing on the recorded cells. An increase in frequency but not amplitude of miniature IPSCs and EPSCs also indicated an AVP enhancement of neurotransmitter release from axon terminals of inhibitory and excitatory interneurons. These observations provide support for a broad presynaptic and postsynaptic distribution of AVP V1 type receptors and indicate that their activation can enhance the excitability of a majority of neurons in neonatal ventral spinal cord.

Original languageEnglish
Pages (from-to)1202-1210
Number of pages9
JournalJournal of Neurophysiology
Volume86
Issue number3
DOIs
Publication statusPublished - 2001
Externally publishedYes

ASJC Scopus subject areas

  • Neuroscience(all)
  • Physiology

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