Українська English

ISSN 2522-9028 (Print)
ISSN 2522-9036 (Online)

Fiziologichnyi Zhurnal

is a scientific journal issued by the

Bogomoletz Institute of Physiology
National Academy of Sciences of Ukraine

Editor-in-chief: V.F. Sagach

The journal was founded in 1955 as
1955 – 1977 "Fiziolohichnyi zhurnal" (ISSN 0015 – 3311)
1978 – 1993 "Fiziologicheskii zhurnal" (ISSN 0201 – 8489)
1994 – 2016 "Fiziolohichnyi zhurnal" (ISSN 0201 – 8489)
2017 – "Fiziolohichnyi zhurnal" (ISSN 2522-9028)

Fiziol. Zh. 2009; 55(2): 44-49

Morphophysiologic properties of delayed firing neurons in substantia gelatinosa of the rat spinal cord

I.V. Melnick

    O.O. Bogomoletz Institute of Physiology, National AcademySciences of Ukraine, Kyiv, Ukraine


Substantia gelatinosa (SG) neurons of the spinal cord are highly heterogeneous in their morphologic and physiologic properties. Based on characteristic firing response evoked by sustained depolarization, neurons can be categorized on three main types: tonic, adapting and delayed firing (DFNs). Here, properties of DFNs in spinal cord slices from 3-5 weeks-old rats were stud-ied with the use of patch-clamp recording and confocal micros-copy. Distinctive features of DFNs were increased rheobase (95.7 ± 11.2 pA) and depolarized threshold to evoke action potential (-37.8 ± 0.7 mV) than in neurons of other types. In volt-age-clamp mode all DFNs expressed high amplitude outward A-type potassium current (KA which started activation at ~ -70 mV, before Na+ current. Structurally, the majority of DFNs had vertically oriented dendritic tree, while their axons were not restricted to SG and projected predominantly to lamina I. Possible physiological functions of DFNs are discussed.

Keywords: Substantia gelatinosa, spinal cord


  1. Melnik IV Physiological types of neurons of gelatinous substance of the spinal cord of rats . Neurophysiology. 2008. 40, N 3. P. 191-198.
  2. Balasubramanyan S., Stemkowsky P.L., Stebbing M.J., Smith P.A. Sciatic chronic constriction injury produces cell-type-specific changes in the electrophysiological properties of rat substantia gelatinosa neurons . J. Neurophysiol. 2006. 96. P. 579-590.3. Dahlhaus A., Ruscheweyh R., Sandkuhler J. Synaptic input of rat spinal lamina I projection and unidentified neurones in vitro . J. Physiol. 2005. 566. P. 355-368.
  3. Eckert W.A., McNaughton K.K., Light A.R. Morphology and axonal arborisation of rat spinal inner lamina II neurons hyperpolarized by m-opioid-selective ago­nists . J. Comp. Neurol. 2003. 458. P. 240-256.
  4. Gobel S. Golgi studies of the substantia gelatinosa neurons in the spinal trigeminal nucleus . Ibid. 1975. 162. P. 397-416.
  5. Gobel S. Golgi studies of the neurons in layer II of the dorsal horn of the medulla (trigeminal nucleus caudalis) . Ibid. 1978. 180. P. 395-414.
  6. Grudt T.J., Perl E.R. Correlations between neuronal morphology and electrophysiological features in the rodent superficial dorsal horn . J. Physiol. 2002. 540. P. 189-207.
  7. B. Heinke, R. Ruscheweyh, L. Forsthuber, G. Wunderbaldinger, J. Sandkuhler, Physiological, neurochemical and morphological properties of a sub­group of GABAergic spinal lamina II neurons identi­fied by expression of green fluorescent protein in mice . J. Physiol. 2004. 560. P. 249-266.
  8. Lopez-Garcia J.A., King A.E. Membrane properties of physiologically classified rat dorsal horn neurons in vitro: correlation with cutaneous sensory afferent in­put . Eur. J. Neurosci. 1994. 6. P. 998-1007.
  9. Lu J., Perl E.R. Modular organization of excitatory circuits between neurons of the spinal superficial dor­sal horn (laminae I and II) . J. Neurosci. 2005. 25. P. 3900-3907.
  10. Melnick I.V. Morphophysiologic properties of islet cells in substantia gelatinosa of the rat spinal cord . Neurosci. Lett. 2008. 446. P. 65-69.
  11. Melnick I.V., Santos S.F., Szocol K. et al. Ionic basis of tonic firing in spinal substantia gelatinosa neurons of rat . J. Neurophysiol. 2004. 91. P. 646-655.
  12. Melnick I.V., Santos S., Safronov B.V. Mechanism of spike frequency adaptation in substantia gelatinosa neurons of rat . J. Physiol. 2004. 559. P. 383-395.
  13. Price D.D., Hayashi H., Dubner R., Ruda M.A. Func­tional relationship between neurons of marginal and sub-stantia gelatinosa layers of primate dorsal horn . J. Neurophysiol. 1979. 42. P. 1590-1608.
  14. Ruscheweyh R., Sandkuhler J. Lamina-specific membrane and discharge properties of rat spinal dor­sal horn neurons in vitro . J. Physiol. 2002. 541. P. 231-244.
  15. Santos S., Melnick I.V., Safronov B.V. Selective post-synaptic inhibition of tonic-firing neurons in substan-tia gelatinosa by m-opioid agonist . Anesthesiology. 2004. 101. P. 1177-1183.
  16. Santos S.F., Rebelo S., Derkach V.A., Safronov B.V. Excitatory interneurons dominate sensory processing in the spinal substantia gelatinosa of rat . J. Physiol. 2007. 581. P. 241-254.
  17. Spike R.C., Todd A.J. Ultrastructural and immuno-cytochemical study of lamina II islet cells in rat spinal dorsal horn . J. Comp. Neurol. 1992. 323. P. 359-369.
  18. Stern J.E. Electrophysiological and morphological properties of pre-autonomic neurones in the rat hy-pothalamic paraventricular nucleus . J. Physiol. 2001. 537. P. 161-177.
  19. Thomson A.M., West D.C., Headley P.M. Membrane characteristics and synaptic responsiveness of super­ficial dorsal horn neurons in a slice preparation of adult rat spinal cord . Eur. J. Neurosci. 1989. 1. P. 479-488.
  20. Todd A.J., Lewis S.G. The morphology of Golgi-stained neurons in lamina II of the rat spinal cord . J. Anat. 1986. 149. P. 113-119.
  21. Yasaka T., Kato G., Furue H. et al. Cell-type-specific ex­citatory and inhibitory circuits involving primary afferents in the substantia gelatinosa of the rat spinal dorsal horn in vitro . J. Physiol. 2007. 581. P. 603-618.
  22. Yoshimura M., Jessell T.M. Membrane properties of rat substantia gelatinosa neurons in vitro . J. Neuro-physiol. 1989. 62. P. 109-118.

© National Academy of Sciences of Ukraine, Bogomoletz Institute of Physiology, 2014-2024.