Barrel rotation evoked by intracerebroventricular vasopressin injections in conscious rats. II. Visual/vestibular interactions and efficacy of antiseizure drugs.
Intracerebroventricular (i.c.v.) arginine-vasopressin (AVP) injections evoke 'barrel rotation' (BR) in rats. This motor system abnormality was studied in a protocol where conscious rats were injected on day 1 with 1 microgram i.c.v. AVP and reexposed to 0.5 micrograms on day 3. Three paradigms modifying visual/vestibular systems were employed: labyrinthectomy, 3-acetylpyridine (3-AP) destruction of the inferior olive and atropine pretreatment. Ambient illumination (light vs dark) was also modified. Initial (day 1) incidence of BR, increased incidence (i.e. sensitization) on day 3, and day 3 BR latency were differentially affected by the various paradigms and suggest a complex role of visual/vestibular input in modifying i.c.v. AVP-induced BR. For example, 3-AP rats tested in light and atropinized rats had a reduced responsiveness to the peptide on day 1. 3-AP-treated rats tested in dark conditions showed a normal incidence of BR on day 1, but the expected sensitization to AVP on day 3 did not occur. Combined labyrinthectomy and darkness did not modify BR incidence on either day, but altered the distribution of latency data. Four diverse antiepileptic drugs were tested for efficacy against i.c.v. AVP-induced BR in sensitized rats: phenytoin, diazepam, valproic acid and phenobarbital; all drugs reduced the proportion of rats with BR and prolonged the latency. We conclude that brain AVP may be involved in abnormal motor conditions that are modified by visual/vestibular neuronal circuits. The unusual motor output (barrel rotation) can be inhibited by diverse antiepileptic drugs.
D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology*; D001127:Arginine Vasopressin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D005133:Eye Movements / Q000187:drug effects*; D007276:Injections, Intraventricular; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D009847:Olivary Nucleus / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012399:Rotation; D014722:Vestibule, Labyrinth / Q000187:drug effects*
D000927:Anticonvulsants; D011725:Pyridines; C010835:3-acetylpyridine; D001127:Arginine Vasopressin