Angiotensin II receptors and angiotensin converting enzyme in the medulla oblongata.

Abstract

Quantitative in vitro autoradiography was used to map angiotensin II (ANG II) receptors and angiotensin converting enzyme (ACE) in sections from rat, rabbit, sheep, and human medulla oblongata and to follow changes in receptor and ACE density after disruption of vagal projections by nodose ganglionectomy in the rat. ANG II receptors and ACE are both concentrated in the nucleus of the solitary tract and dorsal motor nucleus of vagus of the rat, rabbit, sheep, and human. An ANG II receptor-containing band connecting the nucleus of the solitary tract with the dorsolateral medulla was seen in rabbit and human tissue, providing evidence for association of ANG II receptors with vagal afferent fibers. ANG II receptors were found to be concentrated in the rostral and caudal ventrolateral medulla, which corresponded to the region of C1 and A1 catecholamine-containing cell groups in the rabbit. This localization was also evident in rat and human tissue. In all four species, a prominent, ANG II receptor-rich band in the intermediate reticular nucleus was found to connect the ventrolateral medulla and the dorsal vagal complex. In humans and sheep, this band contains puncta that overlie cell bodies. One week after nodose ganglionectomy in the rat, the density of ANG II receptors in the ipsilateral dorsal vagal complex fell markedly. This fall was most prominent in the rostral dorsal motor nucleus of vagus (to 46% of control density) and in the nucleus of the solitary tract (to 56% of control). ACE levels and calcitonin gene-related peptide receptor density were unchanged in both nuclei after ganglionectomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin-II-induced reactive oxygen species along the SFO-PVN-RVLM pathway: implications in neurogenic hypertension

“…For instance, immunohistochemistry studies showing Ang-II-like immunoreactive neurons in the PVN and terminals in the RVLM support the concept that angiotensinergic neurons in the PVN innervate the RVLM (47). Of note, angiotensin receptors, mainly the AT1 receptor subtype, are also present in the RVLM (48) and play an important role in altering the activity of RVLM neurons (49). For example, injection of Ang-II into the RVLM of the cat produces pressor response (50).…”

Physiology of Local Renin-Angiotensin Systems

“…There are suggestions that AT 1 receptors are associated with a range of afferents nerves. AT 1 receptors were detected on cell bodies in nodose ganglion, dorsal root ganglia, and the primary central terminal regions of these neurons, the nucleus of the solitary tract and dorsal laminae of the spinal cord of several species (10,11,516). It has also been suggested that AT 1 receptors occur in the caudal nucleus of the spinal trigeminal tract in the medulla (13) and that they may be associated with the terminals of trigeminal sensory neurons.…”

Brain Angiotensin-II-derived Reactive Oxygen Species: Implications for High Blood Pressure

“…For instance, immunohistochemistry studies showing Ang II-like immunoreactive neurons in PVN and terminals in RVLM support the concept that angiotensinergic neurons in the PVN innervate the RVLM [24]. Of note, angiotensin receptors, mainly AT1R subtype, are also present in the RVLM [25] and plays an important role in altering the activity of RVLM neurons [26]. For example, injection of Ang II into the RVLM of the cat produces pressor response [27].…”