A fetal rat brain stem-spinal cord in vitro preparation (15–20 days) which retains for several hours respiratory-like discharges on cervical and cranial ventral roots has been developed for analysing fetal central respiratory activity. Two different patterns of easily distinguishable rhythmic activity were recorded. The first, of spinal origin, appeared every 2–10 min as long bursts of potentials (3–30 s) on cervical, but not hypoglossal, roots. The second pattern corresponded to brief bursts (1 s) of potentials occurring on both cervical and hypoglossal roots at a frequency ranging from 3–4 cycles min-1. The second type of activity was likely to be respiratory since it originated from the medulla, and behaved similarly to the respiratory activity recorded in vitro from newborn rats. The fetal respiratory-like activity was never observed at day 15, appeared at day 16 in 30% of the preparations with fluctuating frequency and amplitude bursts, and stabilised at day 20 where it was usually present and resembled newborn rat respiratory activity: its frequency was stable but was reduced by withdrawal of CO2 and pH stimuli and modulated by a pontine noradrenergic influence. This fetal preparation offers many advantages for studying the ontogeny of the central respiratory activity because of the background knowledge available on the adult and newborn rat respiratory centers and the possibility of performing electrophysiological, morphological and pharmacological fetal studies directly at the central level without any feedback from the periphery.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
Arata A, Onimaru H, Homma I (1990) Respiratory-related neurons in the ventral medulla of newborn rats in vitro. Brain Res Bull 24: 599–604
Berger AJ (1990) Recent advances in the respiratory neurobiology using in vitro methods. Am J Physiol 259: L24-L29
Bystrzycka E, Nail BS, Purves MJ (1975) Central and peripheral neural respiratory activity in the mature sheep and newborn lamb. Respir Physiol 25: 199–215
Cazalets JR, Grillner P, Menard I, Cremieux J, Clarac F (1990) Two types of motor rhythm induced by NMDA and amines in an in vitro spinal cord preparation of neonatal rat. Neurosci Lett 111: 116–121
Errchidi S, Hilaire G, Monteau R (1990) Permanent release of noradrenaline modulates respiratory frequency in the newborn rat: an in vitro study. J Physiol (Lond) 429: 497–510
Errchidi S, Monteau R, Hilaire G (1991) Noradrenergic modulations of the medullary respiratory rhythm generator in the newborn rat: an in vitro study. J Physiol (Lond) 443: 477–498
Ezure K, Manabe M, Yamada H (1988) Distribution of medullary respiratory neurons in the rat. Brain Res 455: 262–270
Harada Y, Kuno M, Wang YZ (1985) Differential effects of carbon dioxyde and pH on central chemoreceptors in the rat in vitro. J Physiol (Lond) 368: 679–693
Hilaire G, Monteau R, Errchidi S (1989) Possible modulation of the medullary respiratory rhythm generator by the noradrenergic A5 area: an in vitro study in the newborn rat. Brain Research 485: 325–332
Hilaire G, Monteau R, Gauthier P, Rega P, Morin D (1990) Functional significance of the dorsal respiratory group in adult and newborn rats: in vivo and in vitro studies. Neurosci Lett 111: 133–138
Ioffe S, Jansen AH, Chernick V (1983) Chronic extracellular recording of fetal medullary neuronal activity. J Appl Physiol 55: 1361–1364
Jansen AH, Chernick V (1991) Fetal breathing and development of control of breathing. J Appl Physiol 70: 1431–1446
Monteau R, Morin D, Hilaire G (1990) Acetylcholine and central chemosensitivity: in vitro study in the newborn rat. Respir Physiol 81: 241–254
Morin D, Hennequin S, Monteau R, Hilaire G (1990) Serotonergic influences on central respiratory activity: an in vitro study in the newborn rat. Brain Res 535: 281–287
Morin D, Monteau R, Hilaire G (1991) 5-Hydroxytryptamine modulates central respiratory activity in the newborn rat: an in vitro study. Eur J Pharmacol 192: 89–95
Murakoshi T, Suzue T, Tamai S (1985) A pharmacological study on respiratory rhythm in the isolated brainstem-spinal cord of the newborn rat. Br J Pharmacol 86: 95–104
Onimaru H, Arata A, Homma I (1987) Localization of respiratory rhythm generating neurons in the medulla of brainstem-spinal cord preparations from newborn rats. Neurosci Lett 78: 151–155
Onimaru H, Arata A, Homma I (1988) Primary respiratory rhythm in the medulla of brainstem-spinal cord preparation from newborn rat. Brain Res 445: 314–324
Onimaru H, Arata A, Homma I (1989) Firing properties of respiratory rhythm generating neurons in the absence of synaptic transmission in rat medulla in vitro. Exp Brain Res 76: 530–536
Saether K, Hilaire G, Monteau R (1987) Dorsal and ventral respiratory groups of neurons in the medulla of the rat. Brain Res 419: 87–96
Smith JC, Feldman J (1987) In vitro brainstem-spinal cord preparation for study of motor systems for mammalian respiration and locomotion. J Neurosci Meth 21: 321–333
Smith JC, Greer JJ, Liu G, Feldman J (1990) Neural mechanisms generating respiratory pattern in mammalian brainstem-spinal cord in vitro. I. Spatiotemporal patterns of motor and medullary neuron activity. J Neurophysiol 64: 1149–1169
Suzue T (1984) Respiratory rhythm generation in the in vitro brainstem-spinal cord preparation of the neonatal rat. J Physiol (Lond) 354: 173–183
Yamada H, Ezure K, Manabe M (1988) Efferent projections of inspiratory neurons of the ventral respiratory group. A dual labeling study in the rat. Brain Res 455: 283–294
About this article
Cite this article
Pasquale, E.D., Monteau, R. & Hilaire, G. In vitro study of central respiratory-like activity of the fetal rat. Exp Brain Res 89, 459–464 (1992). https://doi.org/10.1007/BF00228263
- Fetal breathing
- Respiratory centers