Sudden Infant Death Syndrome Research Today is a free monthly online journal that collates and summarizes the latest research about Sudden Infant Death Syndrome, including details on sids, causes, prevention, statistics. | ||||||||
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Ventilatory response to hypercapnia and hypoxia after extensive lesion of medullary serotonergic neurons in newborn conscious piglets.Penatti EM, Berniker AV, Kereshi B, Cafaro C, Kelly ML, Niblock MM, Gao HG, Kinney HC, Li A, Nattie EE Department of Physiology, Dartmouth-Hitchcock Medical Center, Borwell Bldg., Lebanon, NH 03756-0001, USA. eliana.m.penatti@Dartmouth.edu Acute inhibition of serotonergic (5-HT) neurons in the medullary raphé (MR) using a 5-HT(1A) receptor agonist had an age-dependent impact on the "CO(2) response" of piglets (33). Our present study explored the effect of chronic 5-HT neuron lesions in the MR and extra-raphé on the ventilatory response to hypercapnia and hypoxia in piglets, with possible implications on the role of 5-HT in the sudden infant death syndrome. We established four experimental groups. Group 1 (n = 11) did not undergo any treatment. Groups 2, 3, and 4 were injected with either vehicle or the neurotoxin 5,7-dihydroxytryptamine in the cisterna magna during the first week of life (group 2, n = 9; group 4, n = 11) or second week of life (group 3, n = 10). Ventilation was recorded in response to 5% CO(2) (all groups) and 12% O(2) (group 2) during wakefulness and sleep up to postnatal day 25. Surprisingly, the piglets did not reveal changes in their CO(2) sensitivity during early postnatal development. Overall, considerable lesions of 5-HT neurons (up to 65% decrease) in the MR and extra-raphé had no impact on the CO(2) response, regardless of injection time. Postlesion raphé plasticity could explain why we observed no effect. 5,7-Dihydroxytryptamine-treated males, however, did present a lower CO(2) response during sleep. Hypoxia significantly altered the frequency during sleep in lesioned piglets. Further studies are necessary to elucidate the role of plasticity, sex, and 5-HT abnormalities in sudden infant death syndrome. Published 15 September 2006 in J Appl Physiol, 101(4): 1177-88.
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