Audiogenic and audiogenic-like seizures: locus of induction and seizure severity determine postictal prolactin patterns.
Audiogenic seizures (AS) are a model of generalized tonic-clonic seizures, evoked by high-intensity (110 dB) acoustic stimulation evaluated by means of behavioral severity indexes (SI). Postictal prolactin (PRL) is a marker of generalized seizures, both in animals and humans. Thus, in the present work we assayed postictal PRL in a) male Wistar AS susceptible (S, n = 5) and AS resistant (R, n = 13) rats made susceptible by specific midbrain lesions. b) In rats electrically stimulated in the central nucleus (CN) of the inferior colliculus (IC) (n = 20), or the cortical IC (CxIC, n = 18). In c) S rats pretreated with either bromocriptine (BRO; 4 mg/kg; SC), a PRL release inhibitor, or vehicle (V), 30 min before the electrical stimulation. Basal PRL was 2-10 ng/ml at time 0. In the S group, only animals with generalized seizures presented a postictal PRL elevation between 5 and 15 min (60-90 ng/ml; p < 0.05). R rats displayed a discrete PRL response lower than that of S animals. CxIC stimulation produced more severe seizures and greater postictal PRL enhancement than CNIC stimulation, always raising at 5-15 min (p < 0.01). BRO blocked the PRL increase even in the presence of higher seizure scores (p < 0.02). The positive correlation between seizure intensity (SI values), site of initiation (central or cortical IC nuclei), and postictal PRL patterns makes this a reliable model for studying the neurochemistry of the postictal phase and the interaction between hormones and epilepsy.
Garcia-Cairasco
N
N
Neurophysiology and Experimental Neuroethology Laboratory, University of São Paulo, Brazil. ngcairas@fmrp.usp.br
Doretto
M C
MC
Ramalho
M J
MJ
Antunes-Rodrigues
J
J
Nonaka
K O
KO
D000161:Acoustic Stimulation; D000818:Animals; D004195:Disease Models, Animal; D008297:Male; D008959:Models, Neurological; D011388:Prolactin / Q000097:blood* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012640:Seizures / Q000378:metabolism*; D013997:Time Factors
D011388:Prolactin