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Acetylcholine combined with acetylcholinesterase blockade within the commissural nucleus of the solitary tract increases respiratory activity
Author(s) -
Furuya Werner Issao,
Bassi Mirian,
Colombari Eduardo,
Menani Jose Vanderlei,
Zoccal Daniel Breseghello,
Almeida Colombari Débora Simões
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.988.3
Subject(s) - microinjections , acetylcholine , physostigmine , chemistry , solitary tract , vagus nerve , endocrinology , cholinergic , medicine , anesthesia , stimulation , microinjection , central nervous system
Acetylcholine (ACh) microinjections in the commissural nucleus of the solitary tract (cNTS) increase phrenic nerve (PN) burst frequency. However, the effects of the activation of cholinergic mechanisms in the cNTS on the activity of other motor respiratory outputs are still unknown. In the present study, we recorded the hypoglossal nerve (HN), cervical vagus nerve (cVN) and PN activities using decorticated arterially‐perfused in situ preparations of juvenile male Holtzman rats (70–90 g, n=8), and evaluated the effects elicited by microinjections of ACh in the cNTS, combined with prior physostigmine administration (PHY, acetylcholinesterase inhibitor) in the same area. Microinjections of ACh (10 mM, 60 nL) were performed 5 min after PHY (1 mM, 40–60 nL, 0.3 and 0.6 mm caudal to calamus scriptorius ) in the cNTS and the changes in the respiratory motor activities were analyzed during 1 min following microinjections. The combination of PHY and ACh within the cNTS induced an initial (6 s after ACh) slight increase in the PN burst frequency (4.8 ± 1.9 vs. vehicle 2.9 ± 1.0%, p > 0.05) and amplitude (9.0 ± 1.8 vs. vehicle 2.7 ± 0.5%, p < 0.05). The amplitude of post‐inspiratory (post‐I) activity in the cVN (18.7 ± 3.8 vs. vehicle 3.5 ± 0.9%, p < 0.05) and the pre‐inspiratory period (pre‐I) of the HN (425 ± 46 vs. vehicle 100 ± 43 ms, p < 0.05) also increased. Sixty seconds after ACh microinjections, PN frequency decreased (−27.1 ± 0.4 vs. vehicle 2.4 ± 0.6 %, p < 0.05). On the other hand, PN amplitude (11.2 ± 0.5 vs. vehicle 3.4 ± 0.3%, p < 0.05), cVN post‐I amplitude (16.5 ± 0.9 vs. vehicle 1.9 ± 0.5%, p < 0.05) and the HN pre‐I period (436 ± 26 vs. vehicle 149 ± 57 ms, p < 0.05) were maintained. The data show that stimulation of cholinergic receptors in the cNTS promotes significant changes in different respiratory motor nerves that resemble the respiratory responses elicited by peripheral chemoreflex activation (early tachypnea followed by bradypnea, increase in the PN and cVN amplitude and increase in the pre‐I period of HN), which might suggest an involvement of cholinergic mechanisms in the cNTS on chemoreflex pathway. Support or Funding Information FAPESP, CAPES and CNPq.