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Noxious somatic inputs to hypothalamic-midbrain projection neurones: a comparison of the columnar organisation of somatic and visceral inputs to the periaqueductal grey in the rat

Published online by Cambridge University Press:  08 March 2002

D. M. Parry
Affiliation:
Department of Physiology, School of Medical Sciences, University of Bristol, Bristol BS8 1TD and Department of Pharmacology, Merck Sharp & Dohme, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, UK
F. M. Semenenko
Affiliation:
Department of Physiology, School of Medical Sciences, University of Bristol, Bristol BS8 1TD and Department of Pharmacology, Merck Sharp & Dohme, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, UK
R. K. Conley
Affiliation:
Department of Physiology, School of Medical Sciences, University of Bristol, Bristol BS8 1TD and Department of Pharmacology, Merck Sharp & Dohme, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, UK
B. M. Lumb
Affiliation:
Department of Physiology, School of Medical Sciences, University of Bristol, Bristol BS8 1TD and Department of Pharmacology, Merck Sharp & Dohme, Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, UK
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Abstract

The induction of Fos protein was used to localise hypothalamic neurones activated by noxious somatic stimulation. This was combined with retrograde transport of fluorescent latex microspheres from identified 'pressor' and 'depressor' sites in the dorsolateral/lateral or ventrolateral columns of the periaqueductal grey (PAG). Fos-positive neurones were found throughout the rostral hypothalamus. Of those neurones activated by noxious somatic stimuli that projected to the PAG all but one was retrogradely labelled from sites that included the lateral column. Only one neurone was double labelled following injection of tracer at a depressor site in the ventrolateral PAG. This is in marked contrast to visceroresponsive hypothalamic neurones, a larger proportion of which project to the PAG and which, as reported previously, preferentially target depressor sites in the ventrolateral sector. These results are discussed in relation to the roles of the anterior hypothalamus and the different functional columns of the PAG in co-ordinating autonomic and sensory functions in response to nociceptive inputs originating in different peripheral domains. Experimental Physiology (2002) 87.2, 117-122.

Type
Rapid Communications
Copyright
© The Physiological Society 2002

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