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Hypotensive but not normotensive haemorrhage increases tryptophan hydroxylase-2 mRNA in caudal midline medulla

Heidi J Brown1, Luke A Henderson, Kevin A Keay

  • 1Pain Management Research Institute, University of Sydney at Royal North Shore Hospital, St Leonards, NSW 2065, Australia.

Neuroscience Letters
|February 18, 2006
PubMed

Severe blood loss triggers shock, a precipitous hypotension and bradycardia. The integrity of (i) neurons in the vasodepressor region of the caudal midline medulla and (ii) central 5-HT neurotransmission are critical for the expression of haemorrhagic shock. This study investigated whether progressive blood loss triggers altered synthesis of 5-HT in the vasodepressor region of the caudal midline medulla by measuring changes in relative expression levels of tryptophan hydroxylase 2 (TpH 2) mRNA, the rate-limiting enzyme in the synthesis of neuronal 5-HT. Hypotensive but not normotensive haemorrhage triggered a significant increase in TpH 2 mRNA in the vasodepressor region of the caudal midline medulla, identifying an important role for 5-HT-containing caudal midline medullary neurons in haemorrhagic shock.

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