[Characteristics of neuronal activity in nucleus accumbens in spontaneously hypertensive rats]

Spontaneously hypertensive rats (SHR) are generally considered as genetic model both for essential hypertension and attention-deficit hyperactivity syndrome. Neuroanatomical substrates and mechanisms of neural disorders in the SHR have not been elucidated. This study aimed to determine if the background impulse activity of Nucleus accumbens, core (NAc) neurons and their reactions evoked by amigdala stimulation in the SHR differ from those of normotensive Wistar rats (WR). Besides that we investigated the influence of microiontophoretic beta-adrenergic receptors agonist isoproterenol administration (5 mM solution; pH 5.0; 10-30 nA) on the NAc neuronal activity. Single unit extracellular recordings were performed under urethane anesthesia. These results showed that percentage of the NAc neurons with bursting discharge pattern of the background impulse activity is significantly (P < 0.001) greater in SHR (42%) compared to WR (13%). Also, more of the NAc neurons in the SHR (27% had cyclic fluctuations of the frequency of background activity with second period than in the WR (4%). Excitatory reactions of the NAc neurons evoked by amigdala stimulation in the SHR had more long duration. Activation of beta-adrenergic receptors under isoproterenol administration allows us to reproduce a burst type of neuronal impulsation and cyclic fluctuations of the NAc background neuronal activity in both kinds of animals. Findings obtained support the possibility that in the SHR beta-adrenergic function within the NAc is enhanced compare to control.