Sex differences in sensitivity to seizures elicited by pentylenetetrazol in mice

Sex differences in sensitivity to seizures elicited by intraperitoneally in jected pentylenetetrazol (PTZ) were studied in 240 (120 males and 120 femal es) adult Swiss mice. Animals were separated into four groups according to the dose that was injected: 40, 50, 60 and 70 mg/kg. Seizure severity was e xpressed by the following scoring scale: (0) no abnormal behavior; (1) myoc lonus; (2) running bouncing (RB) clonus; (3) tonic hind limb extension (THE ). The analyses of the dose-response curves indicated that females were mor e susceptible than males when the 50- and 60-mg/kg doses were used. Specifi cally. females often displayed RE clonus, while males frequently displayed only myoclonus or no abnormal behavior. No signifcant sex differences were demonstrated when either the 40- or the 70-mg/kg doses were used. These dat a indicate that, for a specific range of doses, sex differences in seizure susceptibility can be clearly demonstrated with the use of intraperitoneall y injected PTZ. In this sense, this method could be used as a tool to inves tigate the role played by sexual hormones in regulating the sensitivity of the gamma -aminobutiric acid (GABA(A)) receptor complex (GRC). (C) 2001 Els evier Science Inc. All rights reserved.