Alterations in norepinephrine, serotonin, c-AMP, and transsynaptic induction of tyrosine hydroxylase after spinal cord transection in the rat.
Tyrosine hydroxylase (TH) activity and the concentrations of norepinephrine (NE), serotonin (5-HT), and cyclic adenosine 3',5'-monophosphate (c-AMP) were measured in the heart, adrenals, and brain stem of paraplegic rats. Following spinal cord transection NE concentration in the heart dropped to 30% within 24 hours and that of 5-HT decreased to 60% of control. Tyrosine hydroxylase activity in the adrenals reached a peak at five days and was still twice that of sham-operated controls thirty days later. Five days following transection the TH activity and c-AMP levels in the brain stem were elevated while NE concentration remained low. At seven days, however, NE and 5-HT levels were higher than in controls while TH activity and c-AMP concentration dropped to control levels. The increase in TH activity in the brain stem may be due to curtailed end-product feedback inhibition and to reduced receptor activation. The sustained induction of the adrenal TH is probably a consequence of a continual stimulation of splanchnic nerves.
D000311:Adrenal Glands / Q000032:analysis; D000818:Animals; D001933:Brain Stem / Q000032:analysis; D000242:Cyclic AMP / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000032:analysis; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism*; D013119:Spinal Cord Injuries / Q000378:metabolism*; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis*
D012701:Serotonin; D000242:Cyclic AMP; D014446:Tyrosine 3-Monooxygenase; D009638:Norepinephrine