Forster HV, Hodges MR, Wenninger JM, Pan LG, Klum L, Leekley T, Feroah TR, Brozoski DT (2002) Breathing of awake goats after neurotoxic lesions in the medullary raphe. Neuroscience 2002 Abstracts 321.9. Society for Neuroscience, Orlando, FL.
Summary: Neurokinin I immunoreactive neurons are abundantly present in the medullary raphe of adult goats. We therefore wished to determine the effect on breathing of destroying such neurons using the neurotoxin saporin (SAP) conjugated to substance P (SP). Injections (1 to 10 µl) of SAP-SP were made at one or two sites in the raphe pallidus and/or raphe obscurus of 4 awake goats. Over the subsequent 5 hours, breathing remained near control levels. Within a few days, there was mild to marked hypoventilation in 2 goats and an attenuated CO2 sensitivity in 3 goats but breathing did not become irregular or ataxic in any goat. The attenuated CO2 sensitivity was associated with evidence of airway constriction. Eight to 14 days later, we injected (1 to 10 µl) at the same sites 50mM ibotenic acid (neurotoxic through glutamate receptors). In the awake state, this injection caused a further marked hypoventilation in one goat who became terminally apneic when anesthetized. After this injection, in the other 3 goats, eupneic PaCO2 was stable and CO2. sensitivity was normal or below normal. We conclude that in awake goats, normal eupneic breathing and CO2 sensitivity are dependent on medullary raphe neurokinin and glutamate receptor activity which apparently includes but is not limited to regulation of airway diameter.
Related Products: SP-SAP (Cat. #IT-07)