HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Rathner, J. A. Articles by McAllen, R. M. Search for Related Content PubMed PubMed Citation Articles by Rathner, J. A. Articles by McAllen, R. M.

Cold-activated raphé-spinal neurons in rats

J. A. Rathner, N. C. Owens and R. M. McAllen

1. In a search for sympathetic premotor neurons subserving thermoregulatory functions, medullary raphé-spinal neurons were studied in urethane-anaesthetized, artificially ventilated, paralysed rats. Extracellular unit recordings were made from a region previously shown to drive the sympathetic supplies to tail vessels and brown adipose tissue. Neurons that were antidromically activated by stimulation across the intermediate region of the upper lumbar cord (the origin of the tail sympathetic outflow) were selected for study.
2. Non-noxious cooling stimuli were delivered to the animal's shaved trunk by circulating cold instead of warm water through a water jacket. Cooling increased the activity of 21 out of 76 raphé-spinal neurons by 1.0 ± 0.2 spikes s^-1 °C^-1 for falls in skin temperature of 3-5 °C below a threshold of 35.0 ± 0.6 °C. Their responses followed skin temperature in a graded manner, and did so whether or not there was any change in core (rectal) temperature.
3. Indirect observations suggested that seven of the neurons that were activated by skin cooling were also activated by falls in core temperature (by 2.1 ± 0.7 spikes s^-1 °C^-1 below a threshold of 36.1 ± 0.7 °C), while the remainder were unaffected by core cooling.
4. An additional 7/76 raphé-spinal neurons showed evidence of inhibition (activity reduced by 2.1 ± 0.5 spikes s^-1 °C^-1) when the trunk skin was cooled.
5. Cold-activated raphé-spinal neurons were found in the nuclei raphé magnus and pallidus, centred at the level of the caudal part of the facial nucleus. Their spinal axons conducted at velocities between 3.4 and 29 m s^-1 (median 6.8).
6. Drug-induced rises in arterial pressure partially inhibited the discharge of 6/14 cold-activated raphé-spinal neurons. Weak-to-moderate cardiac modulation (10-70 %) was present in arterial pulse-triggered histograms of the activity of 11/21 cold-activated raphé-spinal neurons, and 6/6 showed evidence of ventilatory modulation (two strongly, four weakly) in pump-triggered histograms.
7. Raphé-spinal neurons responded to cooling in the absence of any change in the electroencephalogram pattern (6/6 neurons).
8. Most cold-activated raphé-spinal neurons responded to noxious tail pinch (13/21 inhibited, 6/21 excited), as did most thermally unresponsive raphé-spinal cells in the same region (19/41 excited, 9/41 inhibited).
9. It is suggested that these cold-activated raphé-spinal neurons may constitute a premotor pathway that drives sympathetically mediated cold defences, such as cutaneous vasoconstriction or thermogenesis. The data are consistent with the hypothesis that a brainstem reflex, with additional descending input signalling body core temperature, may mediate autonomic responses to environmental cooling.

This article has been cited by other articles:

				M. R. Hayes, K. P. Skibicka, and H. J. Grill Caudal Brainstem Processing Is Sufficient for Behavioral, Sympathetic, and Parasympathetic Responses Driven by Peripheral and Hindbrain Glucagon-Like-Peptide-1 Receptor Stimulation Endocrinology, August 1, 2008; 149(8): 4059 - 4068. [Abstract] [Full Text] [PDF]

				C. K. Song, C. H. Vaughan, E. Keen-Rhinehart, R. B. S. Harris, D. Richard, and T. J. Bartness Melanocortin-4 receptor mRNA expressed in sympathetic outflow neurons to brown adipose tissue: neuroanatomical and functional evidence Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2008; 295(2): R417 - R428. [Abstract] [Full Text] [PDF]

				J. W. Brown, E. A. Sirlin, A. M. Benoit, J. M. Hoffman, and R. A. Darnall Activation of 5-HT1A receptors in medullary raphe disrupts sleep and decreases shivering during cooling in the conscious piglet Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2008; 294(3): R884 - R894. [Abstract] [Full Text] [PDF]

				K. M. Hellman, T. S. Brink, and P. Mason Activity of Murine Raphe Magnus Cells Predicts Tachypnea and On-Going Nociceptive Responsiveness J Neurophysiol, December 1, 2007; 98(6): 3121 - 3133. [Abstract] [Full Text] [PDF]

				J. A. DiMicco and D. V. Zaretsky The dorsomedial hypothalamus: a new player in thermoregulation Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2007; 292(1): R47 - R63. [Abstract] [Full Text] [PDF]

				R. M. McAllen The cold path to BAT Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2007; 292(1): R124 - R126. [Full Text] [PDF]

				T. Koganezawa and N. Terui Differential responsiveness of RVLM sympathetic premotor neurons to hypoxia in rabbits Am J Physiol Heart Circ Physiol, January 1, 2007; 292(1): H408 - H414. [Abstract] [Full Text] [PDF]

				Y. Ootsuka and R. M. McAllen Comparison between two rat sympathetic pathways activated in cold defense Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2006; 291(3): R589 - R595. [Abstract] [Full Text] [PDF]

				N. Marina, M. Taheri, and M. P. Gilbey Generation of a physiological sympathetic motor rhythm in the rat following spinal application of 5-HT J. Physiol., March 1, 2006; 571(2): 441 - 450. [Abstract] [Full Text] [PDF]

				M. W. Nason Jr and P. Mason Medullary Raphe Neurons Facilitate Brown Adipose Tissue Activation J. Neurosci., January 25, 2006; 26(4): 1190 - 1198. [Abstract] [Full Text] [PDF]

				R. M. McAllen, M. Farrell, J. M. Johnson, D. Trevaks, L. Cole, M. J. McKinley, G. Jackson, D. A. Denton, and G. F. Egan Human medullary responses to cooling and rewarming the skin: A functional MRI study PNAS, January 17, 2006; 103(3): 809 - 813. [Abstract] [Full Text] [PDF]

				J. A. DiMicco and D. V. Zaretsky The mysterious role of prostaglandin E2 in the medullary raphe: a hot topic or not? Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2005; 289(6): R1589 - R1591. [Full Text] [PDF]

				Y. Ootsuka and R. M. McAllen Interactive drives from two brain stem premotor nuclei are essential to support rat tail sympathetic activity Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2005; 289(4): R1107 - R1115. [Abstract] [Full Text] [PDF]

				Y. Ootsuka and W. W. Blessing Activation of slowly conducting medullary raphe-spinal neurons, including serotonergic neurons, increases cutaneous sympathetic vasomotor discharge in rabbit Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2005; 288(4): R909 - R918. [Abstract] [Full Text] [PDF]

				M. W. Nason Jr. and P. Mason Modulation of Sympathetic and Somatomotor Function by the Ventromedial Medulla J Neurophysiol, July 1, 2004; 92(1): 510 - 522. [Abstract] [Full Text] [PDF]

				K. Nakamura, K. Matsumura, T. Hubschle, Y. Nakamura, H. Hioki, F. Fujiyama, Z. Boldogkoi, M. Konig, H.-J. Thiel, R. Gerstberger, et al. Identification of Sympathetic Premotor Neurons in Medullary Raphe Regions Mediating Fever and Other Thermoregulatory Functions J. Neurosci., June 9, 2004; 24(23): 5370 - 5380. [Abstract] [Full Text] [PDF]

				T. Osaka Thermogenesis elicited by skin cooling in anaesthetized rats: lack of contribution of the cerebral cortex J. Physiol., March 1, 2004; 555(2): 503 - 513. [Abstract] [Full Text] [PDF]

				N. Rentero, A. Cividjian, D. Trevaks, J. M. Pequignot, L. Quintin, and R. M. McAllen Activity patterns of cardiac vagal motoneurons in rat nucleus ambiguus Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2002; 283(6): R1327 - R1334. [Abstract] [Full Text] [PDF]

				M. Tanaka, K. Nagashima, R. M. McAllen, and K. Kanosue Role of the medullary raphe in thermoregulatory vasomotor control in rats J. Physiol., April 15, 2002; 540(2): 657 - 664. [Abstract] [Full Text] [PDF]