Background:
The spontaneously hypertensive rat (SHR) is commonly used as an animal model of attention deficit hyperactivity disorder-like behavioural characteristics. Little is known about the physiology of the SHR and its genetic control, Wistar-Kyoto (WKY). The aim of this research was to investigate the physiology of neurons in a brain area involved in movement initiation, the striatum.
Methods:
Male rats from the Wistar (WI), SHR and WKY strains were anaesthetized with urethane (1.8−2.4 g/kg). In vivo intracellular recordings were obtained using sharp microelectrodes from spiny projection neurons in the dorsal striatum. Cellular properties were measured from electrophysiological records of spontaneous activity and neuronal responses to in-tracellular current injection.
Results:
Recordings were made from 71 striatal spiny projection neurons (WI, n = 24; SHR, n = 24; WKY, n = 23). Most cellular properties were similar across the three rat strains. However, two parameters of action potential firing differed between the SHR and WKY strains. (Current evoked action potential amplitude: SHR 76.5 ± 7.5 mV, WKY 70.1 ± 8.7 mV; duration: SHR 0.60 ± 0.09 ms, WKY 0.67 ± 0.06 ms; P < 0.05 one-way ANOVA.) The cellular properties of the WI strain were intermediate and not significantly different to either SHR or WKY.
Conclusions:
The action potential parameter differences between the SHR and WKY strains may be related to the behavioural differences between the two strains. At the cellular level, this difference may also indicate that the two strains contain differences in membrane conductances in the striatal spiny projection neurons.
