Role of the retrorubral nucleus in striatally elicited orofacial dyskinesia in cats: effects of muscimol and bicuculline

Abstract

Orofacial dyskinesia (OFD) is a disorder characterized by involuntary movements of the oral and facial muscles. OFD attacks can be elicited acutely in cats by local injections of dopaminergic agents into the anterodorsal part (r-CRM) of the caudate nucleus. Because the dopaminergic A8 cell group, being embedded in the retrorubral nucleus (RRN), gives rise to fibres which terminate in the r-CRM, two questions arose: (1) whether the A8 cell group forms part of the circuitry that directs and/or modulates OFD, and (2) whether GABA-ergic compounds in the RRN play a role in OFD, and if so, whether a pharmacological GABA-ergic intervention of the activity in the RRN modulates or mediates OFD. For this purpose, the activity of the RRN was manipulated with local injections of the GABA(A) agonist muscimol and antagonist bicuculline. These local injections into the RRN were subsequently combined with manipulations of dopamine transmission in the r-CRM with local injections of the selective DAi receptor agonist (3,4-dihydroxyphenylimino)-2-imidazoline. The present study shows that local injections of GABA-ergic compounds into the RRN do not elicit OFD attacks in cats, but can modulate oral behaviour elicited from the r-CRM. The latter effect is dose dependent and GABA-ergic specific.

Distinct patterns of neuronal inputs and outputs of the juxtaparaventricular and suprafornical regions of the lateral hypothalamic area in the male rat

“…The retrorubral area has an identified role in orofacial motor control associated with eating and drinking in the rat (Uchida et al, 2005), cat (Joseph et al, 1985; Arts et al, 1998), and monkey (Mora et al, 1977; DeLong et al, 1983). This effect appears to be under tonic GABAergic inhibition: a GABA A receptor antagonist (bicuculline) will elicit repetitive jaw movements when applied directly to the retrorubral area; conversely, a GABA A receptor agonist (muscimol) when applied to the same area will counteract this effect (Uchida et al, 2005).…”

Inputs to the midbrain dopaminergic complex in the rat, with emphasis on extended amygdala‐recipient sectors

“…Along similar lines, reportedly strong non-dopaminergic downstream projections from the RRF provide an anatomical link consistent with RRF modulation of brainstem somatomotor and visceromotor structures (von Krosigk and Smith, 1991; von Krosigk et al, 1992). Electrical and chemical stimulation of the RRF elicits forepaw and orofacial movements in cats and rats (Arts et al, 1998; Arts and Cools, 1998; 1999, 2000) and a projection from CeA to the SNc/RRF in rats has been implicated in Pavlovian responding (Gallagher et al, 1990; Hall et al, 2001; Lee et al, 2005; 2006; 2008; El-Amamy and Holland, 2007). In addition, evidence has been reported for an involvement of CeA interconnections with mainly the caudolateral SNc in the modulation of associative learning (Holland et al, 2000; Gallagher and Holland, 1994; Han et al, 1997; Lee et al, 2005; Holland and Gallagher, 2006).…”

Projections from the rhomboid nucleus of the bed nuclei of the stria terminalis: Implications for cerebral hemisphere regulation of ingestive behaviors

“…The midbrain BSTrh terminal field centered in the caudolateral substantia nigra, adjacent midbrain reticular nucleus, and retrorubral field has been implicated in orofacial movements accompanying eating and drinking (see Mora et al, 1977;DeLong et al, 1983;Joseph et al, 1985;Arts et al, 1998). This region has substantial projections to the parvicellular reticular nucleus (von Krosigk et al, 1992;Iwata et al, 1996;Shammah-Lagnado et al, 1996), implicating it in the descending control of orofaciopharyngeal control.…”