Serotonin and noradrenaline modulate respiratory pattern disturbances evoked by glutamate injection into the pedunculopontine tegmentum of anesthetized rats

• Published in: Sleep (New York, N.Y.) N.Y.), 2005-05, Vol.28 (5), p.560-570
• Main Authors: SAPONJIC, Jasna, CVOROVIC, Jovana, RADULOVACKI, Miodrag, CARLEY, David W
• Format: Article
• Language: English
• Subjects: Anesthesia; Animals; Behavioral psychophysiology; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Glutamic Acid - administration & dosage; Glutamic Acid - adverse effects; Injections; Male; Neurotransmission and behavior; Norepinephrine - metabolism; Pedunculopontine Tegmental Nucleus - drug effects; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rats; Rats, Sprague-Dawley; Respiration Disorders - chemically induced; Serotonin - metabolism; Sleep. Vigilance; Vertebrates: nervous system and sense organs
• ISSN: 0161-8105; 1550-9109
• DOI: 10.1093/sleep/28.5.560

We hypothesized that 2 important neurotransmitters related to behavioral state control, serotonin and noradrenaline, could also be modulators of pedunculopontine tegmental nucleus (PPT)-induced respiratory dysrhythmia. We examined the impact of serotonin and noradrenaline at respiratory control sites in the PPT functionally identified by immediate apnea of 2.5- to 10-second duration, followed by increased variability of breath time (CVT(T)) (P < .04) after locally injecting glutamate in anesthetized rats. Basic sleep and respiratory neurobiology laboratory. Sixteen adult, male Sprague-Dawley rats. Glutamate-induced respiratory responses, including increases of total apnea duration and CVT(T), were not different between groups of rats in which we further tested monoaminergic modulatory effects (for CVT(T) P = .98, and for total apnea duration, P = .80). Serotonin or noradrenaline injected at the same sites as glutamate had equal impact on CVT(T) (P = .34) and on mean total apnea duration (P = .80), but pretreatment of PPT sites with serotonin blocked (remained equal to preinjection; P = .11), whereas pretreatment with noradrenaline potentiated (P = .04) the increment of respiratory-timing variability induced by glutamate. The serotonergic-blocking effect on glutamate-induced respiratory dysrhythmia was specific to the PPT: the respiratory responses induced by glutamate injection outside the PPT were not modulated by serotonin (for CVT(T), P = .46, and for mean apnea duration, P = .99). The opposed impact of serotonin and noradrenaline on PPT-induced respiratory dysrhythmia, in contrast to their convergent regulatory role in behavioral state control, suggests a functionally distinct role for the PPT in respiratory-pattern control independent of rapid eye movement sleep control.