Sources of presumptive glutamergic/aspartergic afferents to the rat ventral striatopallidal region

Abstract

The distribution of presumptive glutamergic and/or aspartergic neurons retrogradely labeled following injections of 3H-D-aspartate (3H-D-Asp) into the ventral striatopallidal region was compared with the distribution of neurons labeled by comparable injections of wheat germ agglutinin-horseradish peroxidase (WGA-HRP). The afferents labeled by 3H-D-Asp were a subset of those labeled by WGA-HRP. The major sources of afferents to the nucleus accumbens and olfactory tubercle that could be labeled by 3H-D-Asp were in the medial frontal and insular cortices; the olfactory cortex; the lateral, basolateral, and basomedial amygdaloid nuclei; and the midline nuclear complex of the thalamus. The corresponding afferents to the ventral pallidum arose in the central, medial, and basomedial amygdaloid nuclei and the midline thalamic nuclei. In addition, the nucleus of the lateral olfactory tract was moderately or heavily labeled by 3H-D-Asp injections into all three areas, and cells were labeled in the subiculum following injection in the anteromedial part of the nucleus accumbens. Conversely the ventral striatopallidal structures themselves were, at best, sparsely labeled by any of the 3H-D-Asp injections. Neurons in the substantia nigra, ventral tegmental area, dorsal raphe, and locus coeruleus were labeled by WGA-HRP but not by 3H-D-Asp, except for an occasional cell in the raphe. The results indicate that 3H-D-Asp is a specific retrograde tracer and suggest that there are widespread, presumably excitatory, glutamergic and/or aspartergic inputs to the ventral striatum and pallidum.

Contribution of NMDA receptors to postsynaptic potentials and paired-pulse facilitation in identified neurons of the rat nucleus accumbens in vitro

“…The EPSP component is likely to be due to monosynaptic activation considering its constant onset latency in spite of varying stimulation intensity. Most probably, these activated glutamatergic fibers originate in limbic structures, such as the hippocampal formation, prefrontal cortex and amygdala (Walaas and Fonnum 1980;Christie et al 1987;Fuller et al 1987). The origin of the IPSP, however, is less clear and cannot be deduced from the present experiments.…”

“…Despite the recently acquired insights into the intrinsic organization of the Acb (Mogenson et al 1980;Heimer et al 1985;Chang and Kitai 1986), little is known about the transmitter mechanisms by which limbic inputs affect the medium spiny neurons that project to the ventral pallidum and mesencephalon (Chang and Kitai 1985;Nauta et al 1978). Glutamate, or related excitatory amino acids, are probably utilized by afferent fibers originating in the hippocampal formation, amygdala, prefrontal cortex and midline thalamic nuclei (Walaas and Fonnum 1980;Christie et al 1987;Fuller et al 1987). In this study the contribution of glutamatergic synapses to fast synaptic responses evoked by afferent or local stimulation in the Acb was investigated using an in vitro slice preparation.…”

Effects of hippocampal damage on reward threshold and response rate during self-stimulation of the ventral tegmental area in the rat

“…The differences in reward thresholds between lesioned and control animals may be due to the destruction of the glutamatergic hippocampal efferents innervating the NACC [15,16,58]. A diminished excitatory glutamatergic signal to the NACC may, by default, amplify the inhibitory mesolimbic DA signal.…”

Glutamatergic input from specific sources influences the nucleus accumbens-ventral pallidum information flow

“…The NAc has two major subregions-the shell and the core-defined by histochemical, electrophysiological, connectivity and cellular criteria (O'Donnell and Grace 1993;Jongen-Relo et al 1994). This structure receives glutamatergic projections from the ventral hippocampus (vHC) (DeFrance et al 1985), which is involved in generating context, task attention and emotion (Fanselow and Dong 2010); the basolateral nucleus of the amygdala (BLA) (Groenewegen et al 1980;McDonald 1991), which mediates emotional behaviour; and the prefrontal cortex (Fuller et al 1987), which modulates activity throughout the limbic system to enable behavioural flexibility. The paraventricular nucleus of the thalamus (PVT) a part of midline and intralaminar thalamus, which is implicated in behavioural responses to psychostimulant drugs Young and Deutch 1998) and the regulation of autonomic and visceral functions (Bhatnagar and Dallman 1999), particularly in response to stress (Bhatnagar et al 2000), also projects to the shell region of the NAc.…”