Differential effects of NMDA antagonists microinjections into the nucleus reticularis pontis caudalis on seizures induced by pentylenetetrazol in the rat.
It has been shown that NMDA antagonists block the tonic but not the clonic component of seizures when they are injected in the oral region of the rat pontine reticular formation (PRF). The participation of the caudal PRF in the effects of NMDA antagonists upon the tonic and the clonic components of generalized seizures induced by pentylenetetrazol (PTZ) is unknown. The aim of the present study was to evaluate the effects of unilateral microinjections of competitive and non-competitive NMDA antagonists, 2-amino-7-phosphonoheptanoic acid (AP-7) and dizocilpine (MK-801), respectively, into the nucleus reticularis pontis caudalis of the rat PRF upon seizures induced by PTZ (70 mg/kg i.p.). MK-801 induced a dose-related decrease both in the incidence of generalized tonic-clonic seizures (GTCS) and in the presence of spikes in the EEG. MK-801 also increased GTCS latency. On the contrary, AP-7 did not have effects on GTCS. Interestingly, it induced ipsilateral circling behavior. These results suggest that in the caudal region of the rat PRF only non-competitive NMDA antagonists should block the generation of tonic and clonic components of generalized seizures.
Manjarrez
J
J
Unidad de Investigaciones Cerebrales, Instituto Nacional de Neurología y Neurocirugía MVS, México, D.F. Mexico.
Alvarado
R
R
Camacho-Arroyo
I
I
D015763:2-Amino-5-phosphonovalerate / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology*; D000818:Animals; D016291:Dizocilpine Maleate / Q000008:administration & dosage / Q000494:pharmacology*; D004569:Electroencephalography / Q000187:drug effects; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008845:Microinjections; D016202:N-Methylaspartate / Q000037:antagonists & inhibitors*; D010433:Pentylenetetrazole; D011149:Pons / Q000187:drug effects* / Q000502:physiology / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D012154:Reticular Formation / Q000187:drug effects* / Q000502:physiology / Q000503:physiopathology; D012640:Seizures / Q000139:chemically induced / Q000503:physiopathology*; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000037:antagonists & inhibitors
D018691:Excitatory Amino Acid Antagonists; D016202:N-Methylaspartate; D016291:Dizocilpine Maleate; D015763:2-Amino-5-phosphonovalerate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; C031231:2-amino-7-phosphonoheptanoic acid; D010433:Pentylenetetrazole