Neuroscience 2003 Abstract
| Presentation Number: | 826.6 |
|---|---|
| Abstract Title: | Microdialysis of 8-OH-DPAT into the medullary raphe of the rat affects the ventilatory response to CO<sub>2</sub> and decreases core body temperature. |
| Authors: |
Taylor, N. C.*1
; Li, A.1
; Nattie, E. E.1
1Dept. of Physiology, Dartmouth Med. Sch., Lebanon, NH |
| Primary Theme and Topics |
Autonomic, Neuroendocrine and Other Homeostatic Systems - Autonomic -- Respiratory regulation |
| Session: |
826. Respiratory Control III Poster |
| Presentation Time: | Wednesday, November 12, 2003 9:00 AM-10:00 AM |
| Location: | Morial Convention Center - Hall F-I, Board # I18 |
| Keywords: | AUTORECEPTOR, SLEEP, SEROTONIN, HYPERCAPNIA |
In conscious rats, disruption of serotonergic neurons in the caudal raphe decreases the ventilatory response to hypercapnia (SFN abstract 221.3, 2002), whereas chronic focal inhibition of serotonin re-uptake here increases the CO2 response (SFN abstract 570.3, 2002). In this study, we determine what role 5HT1A receptors in the caudal raphe play in ventilation during normocapnic and hypercapnic conditions. After surgical instrumentation with microdialysis guide tubes and EEG/EMG electrodes, unanesthetized adult rats were subjected to initial 30-minute microdialysis treatments with artificial cerebrospinal fluid (aCSF) or aCSF containing 1, 10, or 30 mM of the 5HT1A agonist 8-OH-DPAT. Ventilation in room air and in 7% CO2 was then measured in freely-moving animals in a whole body plethysmograph as microdialysis treatment continued. At least 48 hours between dose experiments was allowed for drug wash out. We found that 30 mM 8-OH-DPAT decreased mean tidal volume at 7% CO2 conditions by 21% during wakefulness (p<0.05 one-way RM ANOVA, Dunnett post-hoc comp. to aCSF). Microdialysis of 10 and 30 mM 8-OH-DPAT also was observed to disrupt sleep during the experiments. Interestingly, rats treated with 1, 10, or 30 mM 8-OH-DPAT had significant dose-dependant decreases in core body temperature compared to aCSF (p<0.001 RM ANOVA on ranks, Dunnett post-hoc comp. to aCSF). Mean core body temperatures decreased from 37.8°C during aCSF treatment to 37.3°C during 30 mM 8-OH-DPAT microdialysis. We conclude that it is difficult to target 5HT1A receptors on neurons within the caudal raphe that may be involved in the ventilatory response to CO2, as only very high concentrations of 8-OH-DPAT elicited a change in response. However, microdialysis of 8-OH-DPAT here caused a very clear concentration-dependant decrease in body temperature.
Supported by NIH HL 28066
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2003 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2003. Online.
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