Synaptic Connections to Phrenic Motoneurons in the Decerebrate Rat
Abstract
As Bianchi et al. (2) point out in their recent review of respiratory neurophysiology, the rat is becoming the “animal of choice” for experimentation. This statement is particularly true for neuroanatomical tracing experiments. However, anatomical tracing often does not identify neurons as respiratory nor does it indicate the excitatory or inhibitory nature of interconnections. This information is provided by electrophysiological experimentation, and has mostly been obtained from earlier experiments on cats. It is therefore important to discover whether such information about functional connections among respiratory neurons in cats is also true of rats, rather than to assume that the neuronal organisation is similar. We set out to discover the determinants of phrenic motoneuron membrane potential trajectories in decerebrate rats in a series of projects using electrophysiological techniques. The projects are described in “Results” in separate sections; each with a brief review of previous knowledge and our findings. We have emphasised points of difference between rats and cats.
Keywords
Phrenic Nerve Synaptic Connection Nucleus Tractus Solitarius Experimental Brain Research Respiratory NeuronPreview
Unable to display preview. Download preview PDF.
References
- 1.Berger, A. J. Phrenic motoneurons in the cat: Subpopulations and nature of respiratory drive potentials. Journal of Neurophysiology 42: 76–90, 1979.PubMedGoogle Scholar
- 2.Bianchi, A. L., M. Denavit-Saubié, and J. Champagnat. Central control of breathing in mammals: neuronal circuitry, membrane properties, and neurotransmitters. Physiological Reviews 75: 1–45, 1995.PubMedGoogle Scholar
- 3.Bryant, T. H., S. Yoshida, D. De Castro, and J. Lipski. Expiratory neurons of the Bötzinger complex of the rat: a morphological study following intracellular labelling with biocytin. Journal of Comparative Neurol-ogy 335: 267–282, 1993.CrossRefGoogle Scholar
- 4.De Castro, D., J. Lipski, and R. Kanjhan. Electrophysiological study of dorsal respiratory neurons in the medulla oblongata of the rat. Brain Research 639: 49–56, 1994.PubMedCrossRefGoogle Scholar
- 5.Dobbins, E. G., and J. L. Feldman. Brainstem network controlling descending drive to phrenic motoneurons in rat. Journal of Comparative Neurology 347: 64–86, 1994.PubMedCrossRefGoogle Scholar
- 6.Douse, M. A., J. Duffin, D. Brooks, and L. Fedorko. Role of upper cervical inspiratory neurons studied by cross- correlation in the cat. Experimental Brain Research 90: 153–162, 1992.CrossRefGoogle Scholar
- 7.Duffin, J., and M. A. Douse. Bötzinger expiratory neurones inhibit propriobulbar decrementing inspiratory neurones. NeuroReport 4: 1215–1218, 1993.PubMedCrossRefGoogle Scholar
- 8.Duffin, J., K. Ezure, and J. Lipski. Breathing rhythm generation: focus on the rostral ventrolateral medulla. News in Physiological Sciences 10: 133–140, 1995.Google Scholar
- 9.Duffin, J., and J. Lipski. Monosynaptic excitation of thoracic motoneurones by inspiratory neurones of the nucleus tractus solitarius in the cat. Journal of Physiology 390: 415–431, 1987.PubMedGoogle Scholar
- 10.Duffin, J., and J. van Alphen. Bilateral connections from ventral group inspiratory neurons to phrenic motoneurons in the rat determined by cross-correlation. Brain Research 694: 55–60, 1995.PubMedCrossRefGoogle Scholar
- 11.Duffin, J., and J. van Alphen. Cross-correlation of augmenting expiratory neurons of the Bötzinger complex in the cat. Experimental Brain Research 103: 251–255, 1995.CrossRefGoogle Scholar
- 12.Ezure, K., and M. Manabe. Decrementing expiratory neurons of the Bötzinger complex. II. Direct inhibitory synaptic linkage with ventral respiratory group neurons. Experimental Brain Research 72: 159–166, 1988.CrossRefGoogle Scholar
- 13.Fedorko, L., J. Duffin, and S. J. England. Inhibition of inspiratory neurons of the nucleus retroambigualis by expiratory neurons of the Bötzinger complex in the cat. Experimental Neurology 106: 74–77, 1989.PubMedCrossRefGoogle Scholar
- 14.Fedorko, L., and E. G. Merrill. Axonal projections from the rostral expiratory neurones of the Bötzinger complex to medulla and spinal cord in the cat. Journal of Physiology 350: 487–496, 1984.PubMedGoogle Scholar
- 15.Fedorko, L., E. G. Merrill, and J. Lipski. Two descending medullary inspiratory pathways to phrenic motoneurones. Neuroscience Letters 43: 285–291, 1983.PubMedCrossRefGoogle Scholar
- 16.Hayashi, F., and Y. Fukuda. Electrophysiological properties of phrenic motoneurons in adult rats. Japanese Journal of Physiology 45: 69–83, 1995.PubMedCrossRefGoogle Scholar
- 17.Jiang, C., and J. Lipski. Extensive monosynaptic inhibition of ventral respiratory group neurons by augmenting neurons in the Bötzinger complex in the cat. Experimental Brain Research 81: 639–648, 1990.CrossRefGoogle Scholar
- 18.Jodkowski, J. S., R. D. Guthrie, and W. E. Cameron. The activity pattern of phrenic motoneurons during the aspiration reflex: An intracellular study. Brain Research 505: 187–194, 1989.PubMedCrossRefGoogle Scholar
- 19.Lipski, J., L. Kubin, and J. Jodkowski. Synaptic action of Rβ neurons on phrenic motoneurons studied with spike-triggered averaging. Brain Research 288: 105–118, 1983.PubMedCrossRefGoogle Scholar
- 20.Lipski, J., and E. G. Merrill. Electrophysiological demonstration of the projection from expiratory neurones in rostral medulla to contralateral dorsal respiratory group. Brain Research 197: 521–524, 1980.PubMedCrossRefGoogle Scholar
- 21.Liu, G. S., J. L. Feldman, and J. C. Smith. Excitatory amino acid-mediated transmission of inspiratory drive to phrenic motoneurons. Journal of Neurophysiology 64: 423–436, 1990.PubMedGoogle Scholar
- 22.Mateika, J. H., and J. Duffin. The connections from Bötzinger expiratory neurons to upper cervical inspiratory neurons in the cat. Experimental Neurology 104: 138–146, 1989.PubMedCrossRefGoogle Scholar
- 23.Merrill, E. G., and L. Fedorko. Monosynaptic inhibition of phrenic motoneurons: a long descending projection from Bötzinger neurons. Journal of Neuroscience 4: 2350–2353, 1984.PubMedGoogle Scholar
- 24.Merrill, E. G., and J. Lipski. Inputs to intercostal motoneurons from ventrolateral medullary respiratory neurons in the cat. Journal of Neurophysiology 57: 1837–1853, 1987.PubMedGoogle Scholar
- 25.Merrill, E. G., J. Lipski, L. Kubin, and L. Fedorko. Origin of the expiratory inhibition of nucleus tractus solitarius inspiratory neurones. Brain Research 263: 43–50, 1983.PubMedCrossRefGoogle Scholar
- 26.Monteau, R., and G. Hilaire. Spinal respiratory motoneurons. Progress in Neurobiology 37: 83–144, 1991.PubMedCrossRefGoogle Scholar
- 27.Monteau, R., M. Khatib, and G. Hilaire. Central determination of recruitment order: intracellular study of phrenic motoneurons. Neuroscience Letters 56: 341–346, 1985.PubMedCrossRefGoogle Scholar
- 28.Nakazono, Y., and M. Aoki. Excitatory connections between upper cervical inspiratory neurons and phrenic motoneurons in cats. Journal of Applied Physiology 77: 679–683, 1994.PubMedGoogle Scholar
- 29.Núñez-Abades, P. A., R. Pásaro, and A. L. Bianchi. Localization of respiratory bulbospinal and propriobul-bar neurons in the region of the nucleus ambiguus of the rat. Brain Research 568: 165–172, 1991.PubMedCrossRefGoogle Scholar
- 30.Otake, K., H. Sasaki, K. Ezure, and M. Manabe. Axonal projections from Bötzinger expiratory neurons to contralateral ventral and dorsal respiratory groups in the cat. Experimental Brain Research 72: 167–177, 1988.CrossRefGoogle Scholar
- 31.Ramirez, J. M., and D. W. Richter. The neuronal mechanisms of respiratory rhythm generation. Current Opinion in Neurobiology 6: 817–825, 1996.PubMedCrossRefGoogle Scholar
- 32.Ryback, I. A., J. F. R. Paton, and J. S. Schwaber. Modeling neural mechanisms for genesis of respiratory rhythm and pattern. III. Comparison of model performances during afferent nerve stimulation. Journal of Neurophysiology 77: 2027–2039, 1997.Google Scholar
- 33.Tian, G. -F., and J. Duffin. Connections from upper cervical inspiratory neurons to phrenic and intercostal motoneurons studied with cross-correlation in the decerebrate rat. Experimental Brain Research 110: 196–204, 1996.CrossRefGoogle Scholar
- 34.Tian, G. -F., and J. Duffin. Spinal connections of ventral-group bulbospinal inspiratory neurons studied with cross-correlation in the decerebrate rat. Experimental Brain Research 111: 178–186, 1996.CrossRefGoogle Scholar
- 35.Tian, G. -F., and J. Duffin. Synchronization of ventral-group, bulbospinal inspiratory neurons in the decerebrate rat. Experimental Brain Research 117: 479–487, 1997.CrossRefGoogle Scholar