Recovery of vestibulogastrointestinal symptoms during vestibular compensation after unilateral labyrinthectomy in rats.
BACKGROUND
The loss of unilateral vestibular function causes vestibulogastrointestinal symptoms that include nausea and vomiting. However, the temporal changes occurring on vestibular compensation are unclear. Thus, the temporal changes and the role of the cerebellum in the recovery of vestibulogastrointestinal symptoms after unilateral labyrinthectomy (UL) were investigated in this study.


METHODS
Vestibulogastrointestinal symptoms were evaluated for intestinal transit and geometric center, whereas vestibulo-ocular symptoms were represented by spontaneous nystagmus. Expression of the c-Fos protein was observed in the vestibular nuclei. These were measured at 30 minutes and at 2, 6, and 24 hours after UL in rats.


RESULTS
Intestinal transit was 66.3% +/- 7.6% in the control animals but significantly decreased to 40.7% +/- 7.8%, 46.3% +/- 6.3%, and 48.6% +/- 10.8% at 30 minutes (p < 0.01), 2 hours (p < 0.01), and 6 hours (p < 0.05) after UL, respectively. The intestinal transit showed a recovery to control levels 24 hours after UL. The geometric center was 5.6 +/- 0.4 in control animals but significantly decreased to 2.1 +/- 0.4, 2.9 +/- 0.3, and 4.0 +/- 0.3 at 30 minutes, 2 hours, and 6 hours after UL, respectively (p < 0.01). Recovery of the geometric center to control levels, 24 hours after UL, was reported. Uvulonodullectomy significantly decreased the intestinal transit and geometric center for 24 hours after surgery (p < 0.01). Moreover, UL in uvulonodullectomized animals significantly decreased the intestinal transit and geometric center for 24 hours after surgery (p < 0.01). Pretreatment of the UL animals with MK-801 significantly increased the geometric center 30 minutes after surgery (p < 0.01). Unilateral labyrinthectomy produced spontaneous nystagmus, 28.9 +/- 1.5, 23.3 +/- 1.4, 17.5 +/- 1.5, and 9.2 +/- 0.9 beats per 10 seconds at 30 minutes and at 2, 6, and 24 hours after UL, respectively. Expression of the c-Fos protein was significantly increased in the medial vestibular nuclei and inferior vestibular nuclei at 1, 2, and 6 hours after UL, and the expression was significantly decreased in animals that were pretreated with MK-801 (p < 0.01).


CONCLUSIONS
These results suggest that the recovery of vestibulogastrointestinal symptoms is faster than that of vestibulo-ocular symptoms and that the cerebellum and glutamate have an important role to play in the recovery of symptoms after UL.
Lee
Jae Hee
JH
Department of Physiology, Wonkwang University School of Medicine, Vestibulocochlear Research Center & Brain Research Institute at Wonkwang University, Iksan, Korea.
Ameer
Abduhl Nasir
AN
Choi
Myoung Ae
MA
Lee
Moon Young
MY
Kim
Min Sun
MS
Park
Byung Rim
BR
D000818:Animals; D002531:Cerebellum / Q000502:physiology; D016291:Dizocilpine Maleate / Q000494:pharmacology; D007758:Ear, Inner / Q000502:physiology* / Q000601:surgery*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005767:Gastrointestinal Diseases / Q000503:physiopathology*; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology; D005772:Gastrointestinal Transit / Q000502:physiology; D018698:Glutamic Acid / Q000502:physiology; D007150:Immunohistochemistry; D008297:Male; D009760:Nystagmus, Physiologic / Q000502:physiology; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function; D015837:Vestibular Diseases / Q000503:physiopathology*; D014726:Vestibular Nuclei / Q000502:physiology; D014722:Vestibule, Labyrinth / Q000502:physiology*
D018691:Excitatory Amino Acid Antagonists; D016760:Proto-Oncogene Proteins c-fos; D018698:Glutamic Acid; D016291:Dizocilpine Maleate