Audiogenic and audiogenic-like seizures: locus of induction and seizure severity determine postictal prolactin...

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.