Oral behaviour induced by intranigral muscimol is unaffected by haloperidol but abolished by large lesions of superior colliculus

Abstract

It has been suggested that the GAbAergic striatonigral projection may form part of the efferent pathway responsible for the expression of dopamine-related oral behaviour. Consistent with this suggestion are reports that bilateral injection of the GABA agonist muscimol can produce stereotyped gnawing and biting. We report here two experiments on this effect: (1) A dose of the dopamine receptor blocker haloperidol (0.4 mg/kg), which effectively antagonised oral stereotypy induced by systemically administered apomorphine or intranigral carbachol, had no effect on either the latency or the intensity of the gnawing produced by intranigral muscimol (1 nM); (2) large lesions involving the superior colliculus which effectively suppressed the oral stereotypy induced by 8 mg/kg apomorphine completely abolished the gnawing induced by intranigral injection of muscimol. Collicular lesions suppressed both the gnawing which occurred spontaneously and that elicited by a perioral probe. These findings are consistent with the view that the substantia nigra is a relay station between the caudate nucleus and the superior colliculus in an efferent pathway mediating dopamine-related oral behaviour. In addition, they raise the possibility that such behaviour is produced by the sensitisation of a collicular-mediated perioral reflex.

A GABAergic nigrotectal pathway for coordination of drinking behavior

“…4 ) may be dedicated to orofacial movements. Although the nigrotectal pathway has been implicated in orienting behavior in rodents and primates 9 , we did not observe any stimulation induced head turning ( Supplemental Fig. 7 ), whisking ( Supplemental Fig.…”

“…Previous studies have implicated the SC in the control of experimentally induced oral stereotypy in rats 9-11 . However, whether the SC is necessary for initiating voluntary drinking or the patterning of orofacial motor output during voluntary consummatory behavior in mice is less clear.…”

“…By common consensus, there are multiple parallel basal ganglia networks with functional specialization 4-6 , and the outputs of such networks project to areas like the thalamus, tectum, and reticular formation 7, 8 . Lesion and inactivation studies have suggested that the nigrotectal projections are important for orofacial behaviors 9-11 . Intranigral injections of muscimol (GABA-A agonist) produce oral stereotypy that can be abolished by electrolytic lesions of the superior colliculus 9 .…”

“…Lesion and inactivation studies have suggested that the nigrotectal projections are important for orofacial behaviors 9-11 . Intranigral injections of muscimol (GABA-A agonist) produce oral stereotypy that can be abolished by electrolytic lesions of the superior colliculus 9 . Yet the function of the nigrotectal projections in voluntary orofacial behavior remains poorly understood.…”

Organization of the nigro-tecto-bulbar pathway to the parvicellular reticular formation: a light- and electron-microscopic study in the rat

“…The projections from the substantia nigra pars reticulata (SNr) to the SC have been well known to play a crucial role in orientation movements of the head and eyes Boussaoud and Joseph 1985;Hikosaka and Wurtz 1983;Joseph and Boussaoud 1985;Takada et al 1994). The SNr has also been shown to contain cells that change neuronal activity during orofacial movements (Delong et al 1983;Mora et al 1977) and has been suggested to be involved in regulation of orofacial behavior not only through the nigrobulbar pathway (von Krosigk and Smith 1991;von Krosigk et al 1992;Yasui et al 1992) but also through the nigrotectal pathway (Gunne et al 1988;Taha et al 1982;Welzl et al 1984). According to a pharmacological study by Gunne et al (1988), GABAergic nigro-tectal projections might be implicated in oral movements.…”