Hemispheric asymmetry of pentamethylenetetrazol-induced wave-spike discharges and motor imbalance in rats.

An intrinsic asymmetry of nigrostriatal dopamine system postulated to be responsible for motor imbalance in normal rats (Glick et al., 1976) is believed to create asymmetry of arousal-sensitive wave-spike discharges. In the present study, bilaterally recorded pentamethylenetetrazol (PMZ)-activated wave-spike discharges were correlated with circling behavior in intact rats. Thirteen naive rats (10 male, 3 female) were implanted with electrodes symmetrically placed over the visual cortices, and their rotation directionality was assessed in the rotometer subsequent to administration of d-methamphetamine sul-ate, 1.5 mg/kg, i.p. In 9 rats a PMZ injection, 20 mg/kg, i.p., revealed asymmetric wave-spike bursts. All of them reliably rotated in the dirction opposite to the hemisphere with lower amplitude wave-spike discharges. It is believed that the nigrostriatal dopamine system plays a major role in modulating the asymmetry of wave-spike seizures. The findings are discussed as they relate to asymmetric generalized wave-spike dischanges found in certain petit mal patients.