DEVELOPMENT OF THYROTROPIN-RELEASING-HORMONE AND NOREPINEPHRINE POTENTIATION OF INSPIRATORY-RELATED HYPOGLOSSAL MOTONEURON DISCHARGE IN NEONATAL AND JUVENILE MICE IN-VITRO
Gd. Funk et al., DEVELOPMENT OF THYROTROPIN-RELEASING-HORMONE AND NOREPINEPHRINE POTENTIATION OF INSPIRATORY-RELATED HYPOGLOSSAL MOTONEURON DISCHARGE IN NEONATAL AND JUVENILE MICE IN-VITRO, Journal of neurophysiology, 72(5), 1994, pp. 2538-2541
1. The ontogeny of thyrotropin-releasing hormone (TRH) and norepinephr
ine (NE) potentiation of inspiratory-related hypoglossal (XII) motor n
erve discharge was studied in medullary slices from P0-3, P7, and P11-
14 mice that retain functional networks for respiration. 2. TRH, appli
ed locally to the XII motor nucleus, had no effect on XII inspiratory
burst amplitude in slices from P0-3 mice. By P7 there was significant
potentiation of burst amplitude that increased more than three-fold by
P11-14. NE applied to the XII nucleus produced significant potentiati
on in all age groups. Potentiation increased developmentally with the
largest increase occurring between P0-3 and P7. 3. Thus catecholamine
and TRH modulation of inspiratory-related XII nerve activity increases
during the first two weeks of life; the potentiating effects of NE ap
pear prior to those of TRH. 4. With rhythmically active, transverse me
dullary slices from mice up to 2 wk of age, it is now possible to stud
y the development of XII motoneuron modulation as it relates to respir
atory control of the upper airway.