Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Electrophysiological evidence for the dendritic localization of a calcium conductance in guinea-pig substantia nigra neurones in vitro


Within the substantia nigra, anatomical, neurochemical and pharmacological findings strongly suggest that transmitter and protein are secreted from the dendrites of nigrostriatal neurones. This phenomenon may underlie a non classical modulatory cellular mechanism. Two conductances are generated in nigrostriatal neurones independent of somatic action potentials, that might mediate this modulation. However, these conductances have never been directly nor precisely located specifically within the dendrites. The aim of this study was to record the membrane properties of substantia nigra zona compacta neurones in response to selective sectioning of the population of long ‘apical’ dendrites i.e. the removal of the zona reticulata. Intracellular recordings from substantia nigra zona compacta neurones were made from mesencephalic slices of the guinea-pig brain maintained in vitro. In cells without the apical dendrites, the membrane potential, input resistance and mean firing frequency was not significantly different from the control neurones. However, removal of the substantia nigra zona reticulata virtually abolished one conductance in particular. This conductance, seen in control neurones, is a long lasting slow depolarization which is resistant to tetrodotoxin blockade of sodium channels: rather, it is mediated by the entry of calcium ions and is optimally deinactivated at a hyperpolarised membrane potential. Hence, this study strongly suggests that this conductance is generated exclusively in the ‘apical’ dendrites. It has been postulated that this long lasting calcium conductance is central to the modulation of nigrostriatal neuronal excitability. Thus, the ‘apical’ dendrites could play a specific and active role in the functioning of nigrostriatal neurones.

This is a preview of subscription content, log in to check access.


  1. Butcher LL, Woolf NJ (1982) Monoaminergic-cholinergic relationship in the chemical communication matrix of the substantia nigra and striatum. Brain Res Bull 9: 475–492

  2. Cheramy A, Leviel V, Glowinski J (1981) Dendritic release of dopamine in the substantia nigra. Nature 289: 537–542

  3. Greenfield SA (1985) The significance of dendritic release of transmitter and protein in the substantia nigra. Neurochem Int 7: 887–901

  4. Greenfield SA, Granewald R, Foley PF, Shaw SG (1983) Origin of various enzymes released from the substantia nigra and caudate nucleus: effects of 6-OHDA lesions of nigrostriatal pathway. J Comp Neurol 214: 87–92

  5. Greenfield SA, Jack JJB, Last ATJ, French M (1988) An electrophysiological action of acetylcholinesterase independent of its catalytic site. Exp Brain Res 70: 441–444

  6. Henderson Z, Greenfield SA (1984) Ultrastructural localization of acetylcholinesterase in the substantia nigra: a comparison between rat and guinea-pig. J Comp Neurol 230: 278–286

  7. Juraska JM, Wilson CJ, Groves PM (1977) The substantia nigra of rat in a Golgi study. J Comp Neurol 172: 585–600

  8. Kita T, Kita H, Kitai ST (1986) Electrical membrane properties of rat substantia nigra compacta neurons in an in vitro slice preparation. Brain Res 372: 21–30

  9. Lacey MG, Mercuri NB, North RA (1987) Dopamine acts on D2 receptors to increase potassium conductance in neurones of the rat substantia nigra zona compacta. J Physiol 392: 397–416

  10. Llinás R, Greenfield SA, Jahnsen H (1984) Electrophysiology of pars compacta cells in the in vitro substantia nigra — a possible mechanism for dendritic release. Brain Res 294: 127–132

  11. Nedergaard S, Hopkins C, Greenfield SA (1988) Do nigro-striatal neurones possess a discrete dendritic modulatory mechanism? Electrophysiological evidence from the actions of amphetamine in brain slices. Exp Brain Res 69: 444–448

  12. Wassef M, Berod A, Sotelo C (1981) Dopaminergic dendrites in pars reticulata of the rat substantia nigra and their striatal input: combined immunocytochemical localization of tyrosine-hydroxylase and anterograde degeneration. Neuroscience 6: 2125–2139

  13. Weston J, Greenfield SA (1986) Release of acetylcholinesterase in the rat nigrostriatal pathway: relation to receptor activation and firing rate. Neuroscience 7: 1079–1088

Download references

Author information

Correspondence to N. C. Harris.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Harris, N.C., Ramsay, S., Kelion, A. et al. Electrophysiological evidence for the dendritic localization of a calcium conductance in guinea-pig substantia nigra neurones in vitro. Exp Brain Res 74, 411–416 (1989).

Download citation

Key words

  • Substantia nigra
  • Dendrites
  • Calcium conductance
  • Intracellular recording