Hypotensive but not normotensive haemorrhage increases tryptophan hydroxylase-2 mRNA in caudal midline medulla.
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.
Pain Management Research Institute, University of Sydney at Royal North Shore Hospital, St Leonards, NSW 2065, Australia.
Heidi J
HJ
Brown
Luke A
LA
Henderson
Kevin A
KA
Keay
D000818:Animals; D006470:Hemorrhage / Q000150:complications / Q000201:enzymology*; D007022:Hypotension / Q000201:enzymology* / Q000209:etiology; D008297:Male; D008526:Medulla Oblongata / Q000201:enzymology*; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014365:Tryptophan Hydroxylase / Q000096:biosynthesis* / Q000235:genetics
D012333:RNA, Messenger; D014365:Tryptophan Hydroxylase; C504569:tph2 protein, rat