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EFFECT OF SYSTEMIC ADMINISTRATION OF 5‐HTP ON RESPIRATORY MUSCLE IN SLEEPING RATS
Author(s) -
Chou YangLing,
Stanley Jessie T.,
Berry Richard B.,
Davenport Paul W.,
Anderson Jeff J,
Hayward Linda F
Publication year - 2006
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.20.4.a379-c
Subject(s) - systemic administration , respiratory system , administration (probate law) , medicine , anesthesia , biology , political science , law , microbiology and biotechnology , in vivo
In the anesthetized, vagotomized rat, intravenous administration of L‐5‐hydroxytryptophan (5‐HTP, 5 mg/kg), the immediate precursor to serotonin, significantly increases genioglossus (GG) activity. The present study was undertaken to assess whether 5‐HTP can also stimulate GG activity in the conscious, behaving rat. Six male Sprague Dawley rats were anesthetized and instrumented with GG and neck muscle EMG electrodes. EEG electrodes were implanted to acquire sleep stage. One week following surgery, rats received intraperitoneal injections of vehicle (3% ethanol in saline) and 5‐HTP (25 mg/kg) in random order on alternate days. Sleep stage and muscle activity was recorded for 6 hrs. Averaged neck and GG EMG activities were measured and expressed as a percentage of the EMG levels during the pre‐injection active wake period. 5‐HTP administration significantly (p<0.05) decreased sleep time (22±3% vs 35±2%, 5‐HTP vs vehicle) and increased sleep onset latency (65±15 vs 22±4 min., 5‐HTP vs vehicle) compared to vehicle. Neck EMG activity was significantly elevated (p<0.05) compared to vehicle at 1 hr post 5‐HTP injection during both NREM and REM sleep. GG activity was not significantly changed during any sleep stage. These results suggest that 25 mg/kg 5‐HTP administration increases sleep latency and increases neck activity in the rat during sleep but does not change GG activity. Support: Cypress Bioscience and NIH [LFH]