Identification and electrophysiology of isolated pars compacta neurons from guinea-pig substantia nigra

Neuroscience. 1991;43(1):81-93. doi: 10.1016/0306-4522(91)90419-o.

Abstract

Single neurons from the substantia nigra of the adult guinea-pig were dissociated. Two morphological types of neurons were identified: (i) large multipolar neurons (20-40 microns greatest diameter) and (ii) small fusiform neurons (less than 20 microns diameter). Neurons of both types showed catecholamine fluorescence and were retrogradely labelled by rhodamine-conjugated microspheres injected into the striatum. Two types of neuron (Type A and Type B) were also identified electrophysiologically in perforated patch recordings of membrane potential and whole-cell current. Type A neurons had a low spontaneous firing frequency (5 Hz) broad action potentials (4 ms) and a threshold of approximately -45 mV. They were inhibited by the dopamine D2 receptor agonist, quinpirole. Type B neurons were characterized by a faster firing frequency (25 Hz), shorter action potential duration (1.5 ms) and a threshold of approximately -50 mV. These cells were unaffected by quinpirole. Large multipolar neurons were usually found to be of the A type and small fusiform, neurons of the B type. The properties of the large multipolar, Type A neurons suggest that they form part of the nigrostriatal, dopaminergic population of the pars compacta.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / drug effects
  • Animals
  • Catecholamines / metabolism
  • Dopamine Agents / pharmacology
  • Electrophysiology
  • Ergolines / pharmacology
  • Fluorescence
  • Guinea Pigs
  • Immunohistochemistry
  • In Vitro Techniques
  • Male
  • Membrane Potentials / physiology
  • Neurons / physiology*
  • Neurotransmitter Agents / metabolism
  • Quinpirole
  • Receptors, Dopamine / drug effects
  • Receptors, Dopamine D2
  • Rhodamines
  • Substantia Nigra / cytology
  • Substantia Nigra / physiology*
  • Sulpiride / pharmacology
  • Synapses / physiology

Substances

  • Catecholamines
  • Dopamine Agents
  • Ergolines
  • Neurotransmitter Agents
  • Receptors, Dopamine
  • Receptors, Dopamine D2
  • Rhodamines
  • Quinpirole
  • Sulpiride