Total Transecion of the Hippocampal Commissure Suppresses Kainic Acid-Induced Amygdalar Seizures in Rats
Abstract number :
2.068
Submission category :
Year :
2001
Submission ID :
1681
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
S-I. Imamura, M.D., Neurosurgery, University of Kagoshima, Kagoshima, Japan; S. Tanaka, M.D., Neuropsychiatry, University of Kagoshima, Kagoshima, Japan; K. Akaike, M.D., Neuropsychiatry, University of Kagoshima, Kagoshima, Japan; H. Tojo, M.D., Neuropsyc
RATIONALE: Though the bilateral hippocampi in the rat may interact from one another in limbic seizures, the exact correlation between them remains obscure. This study was designed to investigate the effects of total transection of the dorsal and ventral hippocampal commissures, which link bilateral hippocampi, on kainic acid (KA) -induced amygdalar seizures.
METHODS: A total of 26 rats were divided into three groups. Ten rats underwent transection using a modified wire knife (transection group); 16 others were untransection group (n=10) and controls (n=6). All the rats then underwent stereotactic implantation of electrodes in the left amygdala (LA), right amygdala (RA), left hippocampus (LH), right hippocampus (RH), right sensorimotor cortex (RCx ) and the left sensorimotor cortex (LCx). A stainless steel cannula also was introduced into the LA. Rats except controls later received 1.0 microgram of KA via the cannula. Controls received phosphate buffer solution alone.
RESULTS: In the untransection group, multiple spike discharges in the LA immediately propagated concurrently to the LH, RH and RA. Propagation involved the LCx and RCx to become status epilepticus 1 to 2 hours after KA injection. Seizures, characterized by mastication, salivation, facial twitching, forelimb clonus , and sometimes rearing and falling, lasted 1 to 2 days. Microscopic examination revealed severe neuronal cell damage in the LA and LH. In the transection group, multiple spike discharges initiated from the LA and were propagated to LH, but involvement was slight in RA, RH, LCx and RCx. Status epilepticus involved only the LA and LH 1 to 2 hours following KA injection. Seizures subsided within 24 hours, showing no ictal manifestations except for aggressiveness. Overall, seizures were weak and transient compared with those in untransection group. Histologically, hippocampal neuronal damage was slight. No electroclinical and histological changes were seen in controls.
CONCLUSIONS: These results indicated that correlation between the bilateral hippocampi is important for full development of KA-induced amygdalar seizures.
Support: Grant-in-Aid for Encouragement of Young Scientists from the Ministry of Education, Sciences, and Culture of Japan; grant from the La Salle High School Graduates[ssquote] Association (Medical Division in Kagoshima)
Disclosure: Grant - Grant-in-Aid for Encouragement of Young Scientists from the Ministry of Education, Sciences, and Culture of Japan; grant from the La Salle High School Graduates[ssquote] Association (Medical Division in Kagoshima)