Apomorphine‐induced modulation of neural activities in the ventrolateral striatum of rats

Abstract

The dopaminergic system in the ventrolateral portion of the striatum (Svl), part of the basal ganglia, regulates orofacial movements; bilateral co-stimulation of both dopamine D1 -like and D2 -like receptors elicits repetitive jaw movements in rats. However, how the activities of Svl neurons are modulated by the activation of dopaminergic receptors remains unknown. We systematically injected apomorphine, a non-selective dopamine receptor agonist that induced jaw movements under urethane anesthesia, and performed multi-channel unit recording from Svl neurons. The Svl neurons were classified into two subgroups: (1) the phasically active (PA) neurons represented by mainly the medium spiny neurons and the GABAergic interneurons in part, and (2) the tonically active (TA) neurons composed of mainly the cholinergic interneurons. Apomorphine modulated PA neuron firing frequency with wide variability; 33.3% of the PA neurons were facilitated, while 38.3% were suppressed. In the majority of TA neurons, the firing frequency was reduced by apomorphine (71.1%). The cross-correlations between PA and PA, PA and TA, and TA and TA neurons were analyzed, and pairs of PA neurons and pairs of PA and TA neurons, showed negligible apomorphine-induced effect on the number of synchronized spikes. In contrast, pairs between TA neurons showed a consistent decrease in the number of synchronized spikes. The apomorphine-induced suppression of TA neuron activities with decreased synchronized outputs is likely to reduce the amount of locally released acetylcholine, which may contribute to the induction of apomorphine-induced jaw movements in rats.

Haloperidol-induced changes in neuronal activity in the striatum of the freely moving rat

“…Similarly, an acute block of the MFB by TTX also increases the firing rate (Prosperetti et al, 2013). Interestingly, while apomorphine likewise suppresses the firing rates of TANs (Fujita et al, 2013), D-Amphetamine, which increases the release of dopamine and inhibits its re-uptake, leads to an increased firing rate of TANs (Kish et al, 1999). In the non-human primate, no effect on spontaneous discharge rate of TANs by localized microinjections of either a D2 antagonist (sulpiride) or a D1 antagonist (SCH23390) (Watanabe and Kimura, 1998), or by unilateral dopamine depletion by MPTP infusion to the caudate-putamen complex (Aosaki et al, 1994a), was observed in the striatum.…”

Spatiotemporal profiles of dental pulp nociception in rat cerebral cortex: An optical imaging study

“…Male Sprague‐Dawley rats (Sankyo Laboratories) weighing 200.1 ± 4.5 g ( n = 11) were anesthetized as above. The surgical and recording procedures were as described previously (Fujita et al, ). A small craniotomy and resection of the dura mater was carefully performed to insert a recording electrode into the left side of the IC.…”

Optogenetics enables functional analysis of human embryonic stem cell–derived grafts in a Parkinson's disease model

“…Unilaterally lesioned animals before transplantation (LES., green and black bars, n = 9, Supplementary Video 6) showed a strong preference for pellet retrieval ipsilateral to the lesion. Injection of the dopamine-receptor-agonist apomorphine, which signals through lesion-sensitized dopamine receptors on medium spiny neurons (MSNs) 22,23 and striatal interneurons 22 , resulted in an inversion of pellet retrieval behavior (green LES. bar + APO and Supplementary Video 7).…”