Distribution of bombesin-like immunoreactivity in the nucleus of the solitary tract and dorsal motor nucleus of the rat and human: Colocalization with tyrosine hydroxylase

Abstract

Bombesin is a peptide neurotransmitter/neuromodulator with important autonomic and behavioral effects that are mediated, at least in part, by bombesin-containing neurons and nerve terminals in the nucleus of the solitary tract (NTS) and the dorsal motor nucleus of the vagus (DMV). The distribution of bombesin-like immunoreactive nerve terminals/fibers and cell bodies in relation to a viscerotopically relevant subnuclear map of this region was studied by using an immunoperoxidase technique. In the rat, bombesin fiber/terminal staining was heavy in an area that included the medial subnucleus of the NTS and the DMV over their full rostral-caudal extent. Distinctly void of staining were the gelatinous, central, and rostral commissural subnuclei and the periventricular area of the NTS, regions to which gastric, esophageal, cecal, and colonic primary afferents preferentially project. The caudal commissural and dorsal subnuclei had light bombesin fiber/terminal staining, as did the intermediate, interstitial, ventral, and ventrolateral subnuclei. With colchicine pretreatment, numerous cell bodies were stained in the medial and dorsal subnuclei, with fewer neurons in the caudal commissural, intermediate, interstitial, ventral, and ventrolateral subnuclei. Bombesin-like immunoreactive neurons were found in numerous other areas of the brain, including the ventrolateral medulla, the parabrachial nucleus, and the medial geniculate body. In the human NTS/DMV complex, the distribution of bombesin fiber/terminal staining was very similar to the rat. In addition, occasional bombesin-like immunoreactive neurons were labeled in a number of subnuclei, with clusters of neurons labeled in the dorsal and ventrolateral subnuclei. Double immunofluorescence studies in rat demonstrated that bombesin colocalizes with tyrosine hydroxylase in neurons in the dorsal subnucleus of the NTS. Bombesin does not colocalize with tyrosine hydroxylase in any other location in the brain. In conclusion, the distribution of bombesin in the NTS adheres to a viscerotopically relevant map. This is the anatomical substrate for the effects of bombesin on gastrointestinal function and satiety and its likely role in concluding a meal. The anatomic similarities between human and rat suggest that bombesin has similar functions in the visceral neuraxis of these two species. Bombesin coexists with catecholamines in neurons in the dorsal subnucleus, which likely mediate, in part, the cardiovascular effects of bombesin.

Intrathecal bombesin is sympathoexcitatory and pressor in rat

“…Centrally, moderate, to high bombesin immunoreactivity is found in neurons and fibers in the nucleus tractus solitarius (NTS), RVLM, CVLM, PVN, and spinal cord (11,35). NTS microinjection or intracerebroventricular bombesin potentiates respiration (22,26) and increases plasma catecholamines (6).…”

Prenatal activation of maternal TLR3 receptors by viral-mimetic poly(I:C) modifies GluN2B expression in embryos and sonic hedgehog in offspring in the absence of kynurenine pathway activation

“…Markers to assess changes in specific neuron populations were chosen when whole brain analyses were not likely to compromise any significant changes. In the case of TH, for example, the enzyme is distributed very widely throughout the CNS 27,28 , including many regions of hindbrain 29,30 , cerebral cortex 31 , amygdala 32 , hippocampus 33,34 and hypothalamus 35,36 and it was decided to examine the overall changes, not limited to the nigrostriatal and tegmento-accumbens pathways in the midbrain and striatal regions.…”

Decreased Bombesin Peptide Response to Cigarette Smoking in Schizophrenia

“…However, urinary bombesin likely has sources in addition to pulmonary cells. Bombesinlike peptide is also found in cerebrospinal fluid (CSF), where it presumably comes from the neuroendocrine cells that form the catecholamine-producing neurons of the brain (Lynn et al 1996). Bombesin-like peptide levels in CSF of schizophrenic psychiatric patients have been shown to be lower than bombesin-like peptide levels in nonschizophrenic psychiatric patients in two (Continued) studies (Gerner and Yamada 1982;Gerner et al 1985), although nicotine exposure was not controlled in either study.…”