Ascending Projections from the Area Postrema and the Nucleus of the Solitary Tract of Suncus Murinus

Abstract

Summary: Suncus murinus (suncus) is a new experimental animal model for research on the mechanisms underlying emesis. In the present study, we examined the ascending projections from the area postrema (AP) and the nucleus of the solitary tract (NTS) in suncus based on anterograde transport of phaseolus vulgaris leucoagglutinin. The AP projected heavily to the dorsal vagal complex, especially in the commissural and medial subnuclei of the NTS, and the dorsal motor nucleus of the vagus. Some ascending fibers from the AP projected bilaterally to the parabrachial nucleus (Pb), but no labeling was observed rostral to this area. In contrast, the NTS had extensive projections as far as the basal forebrain. The NTS projections were observed in the AP, ventrolateral reticular formation including the nucleus ambiguus, A5 noradrenergic area, locus coeruleus, Pb, and central gray matter of the midbrain. At the level of the diencephalon, the NTS projections were seen in the dorsomedial, lateral, paraventricular, periventricular, supraoptic, retrochiasmatic and arcuate nuclei of the hypothalamus, in addition to the paraventricular nucleus of the thalamus. Terminal fields within the basal forebrain were also shown to include the medial preoptic area, the bed nucleus of the stria terminalis, the substantia innominata and the ventral pallidum.The results indicated that the neurological relationship between the chemo-and/or barosensitive systems including the trigger of the emetic response and the general viscerosensory and/or -motor systems may exist also in the suncus.

Slow Hyperpolarization in Cortical Neurons: A Possible Mechanism Behind Vagus Nerve Simulation Therapy for Refractory Epilepsy?

“…Future comparative studies in different parts of the cortex may reveal topographical differences in this response, and such studies are in preparation in our laboratory. Vagal inputs to the different cortical areas may be mediated via thalamic nuclei and also via the parabrachial nucleus (19), the periaqueductal grey matter (20), and locus coeruleus (2 I ) together with direct projections from the nucleus of the solitary tract (22). Putative neurotransmitters in neurons along these pathways may include norepinephrine or y-aminobutyric acid (GABA), of which both have anticonvulsive applications and have been shown to modulate synaptic transmission in the cortex (23)(24)(25).…”

Emetic Responses and Neural Activity in Young Musk Shrews during the Breast-Feeding/Weaning Period: Comparison between the High and Low Emetic Response Strains Using a Shaking Stimulus

“…We speculated that neurons in this region may function not as "a trigger center", but rather as "a modulator center" of vomiting that connects with other related regions. Indeed, reticular formation around the Amb received dense inputs from the NTS in musk shrews [7]. Further studies are necessary to clarify the exact function of this area.…”

“…The NTS receives emetic input from the vagus nerve and AP [7,9]. The NTS neurons receive dual input from the vestibular labyrinth and abdominal vagal nerve, being involved in the control of motion sickness [4,18].…”

Evidence for a Re-Evaluation of the Neurochemical and Anatomical Bases of Chemotherapy-Induced Vomiting

“…The central pattern generator appears to be heavily innervated with NK 1 receptor-containing fibers, and information from pharmacological studies suggests that glutamatergic neurotransmissionviaAMPA/kainatereceptorsisalsoinvolved. 53,61,77,81 3. Dopamine: Synthesis, Storage, Release, Degradation, and Receptors Dopamine (DA) is a neurotransmitter in both the CNS and the periphery.…”