Dopamine ?-hydroxylase-like immunoreactivity in the rat and cat carotid body: a light and electron microscopic study

Abstract

Immunocytochemical localization of dopamine beta-hydroxylase (DBH) was used to study the synthesis and storage sites of norepinephrine (noradrenaline) in the rat and cat carotid bodies. In the rat carotid body some parenchymal cells exhibited strong DBH-like immunoreactivity (DBH-I), while others displayed only faint DBH-I. In a typical parenchymal cell cluster, most cells with strong DBH-I were irregular in shape and appeared to partially surround those with weak DBH-I which usually were rounded in contour. In the cat carotid body most parenchymal cells showed a strong to moderate DBH-I. In both the rat and cat carotid bodies varicose nerve fibres with DBH-I were associated primarily with blood vessels. All autonomic ganglion cells examined, which were associated with the rat carotid body, showed DBH-I. Electron microscopy revealed that most DBH-I in the strongly positive cells of the rat carotid body was associated with dense granules (possibly corresponding to dense-cored vesicles of various sizes), although some was found in other sites. In oval cells with less DBH-I, reactivity resided in some of the large granules. In the cat carotid body the glomus cells contained more granules of various sizes and shapes than did those of the rat carotid body. Most of the cat glomus cell granules exhibited DBH-I activity. Our results indicate that some of glomus cells in the rat and most of the glomus cells in the cat contain DBH and therefore may be sites of norepinephrine synthesis.

Gene expression in peripheral arterial chemoreceptors

“…More consistent findings have been reported in the rat. Nerve fibers within the carotid body and petrosal ganglion cell bodies of the rat are positive for SP immunoreactivity (Chen et al, 1986;Jacobowitz and Helke, 1997;Wharton et al, 1980) The findings in the goat are the same as in the rat; SP immunoreactivity is only localized to the nerve fibers of the goat carotid body (Pizarro et al, 1995). Of particular interest is that in the human carotid body SP immunoreactivity is also only seen in nerve fibers and not in glomus cells using light and electron microscopy (Kummer and Habeck, 1991).…”

“…Furthermore, SP immunoreactivity has been found in the carotid body of several animal species, although the specific cellular distribution of the protein to either carotid sinus nerve fibers or glomus cells appears to be speciesand investigator-dependent. For example, SP immunoreactivity is found in both glomus cells and the nerve fibers innervating the carotid body of the cat by Wang et al (1992) but only in nerve fibers of this species in studies performed by Chen et al (1986). While all published reports in the rabbit have localized SP immunoreactivity to nerve fibers within the carotid body (Wharton et al, 1980;Kim et al, 2001;Kusakabe et al, 1994), there is inconsistent data concerning whether SP immunoreactivity is localized to glomus cells of this species (Kusakabe et al, 1994).…”

“…Several in vitro studies have demonstrated a stimulus-specific release of norepinephrine vs. dopamine from the carotid body: hypoxic exposure preferentially releases dopamine, while nicotine preferentially releases norepinephrine (Chen et al, 1997;Vicario et al, 2000). In addition to norepinephrine, immunoreactivity (Chen et al, 1985;Wang et al, 1991a) and mRNA for D␤H (the enzyme for norepinephrine synthesis) have been detected in the carotid body ). However, petrosal ganglion neurons do not synthesize norepinephrine and neither D␤H immunoreactivity nor its mRNA have been detected in the cell bodies of these neurons Gauda et al, 2001).…”

Innervation of the carotid body: Immunohistochemical, denervation, and retrograde tracing studies

“…In the human, cat, rabbit, rat, guinea pig, and chicken carotid body, many nerve fibers contain CGRP-, SP-, GAL-, NPY-, and VIP-IR (Chen et al, 1986;Finley et al, 1992Finley et al, , 1995Hyme and Kummer, 1989;Jacobowitz and Helke, 1980;Kameda, 1989Kameda, , 1990a1998, 1999Kondo and Yamamoto, 1988;Kondo et al, 1986;Kummer and Habeck, 1991;Kummer et al, 1989a, b;Kusakabe et al, 1994Kusakabe et al, , 1998aTorrealba and Correa, 1995;Wharton et al, 1980;Yamamoto et al, 1989) (Table 1). These nerve fibers are detected around the blood vessels as well as around the clusters of glomus and sustentacular cells.…”

“…The jugular ganglion contains few IR neurons (Ichikawa et al, 1991). In the Kameda, 1989, 1990a,b, 1998 Hyme and Kummer, 1989Kummer, 1988Kummer et al, 1989a,b Human Kummer and Habeck, 1991Rat Ichikawa and Helke, 1993Kondo and Yamamoto, 1988Kummer et al, 1989bKusakabe et al, 1998a Chicken Kameda, 1989;1999Rat Finley et al, 1995 Chicken Kameda, 1990a,b, 1999Yamamoto et al, 1989Guinea pig Kummer, 1990Kummer at al., 1989bRat Kondo et al, 1986Kummer at al., 1989bKusakabe et al, 1998a Cat Chen et al, 1986Heym and Kummer, 1989Wharton et al, 1980Chicken Kameda, 1989, 1990a, b, 1998Guinea pig Heym and Kummer, 1989Kummer et al, 1989a1989bHuman Kummer and Habeck, 1991Rabbit Heym and Kummer, 1989Kusakabe et al, 1994Rat Hardebo et al, 1989Helke et al, 1980bJacobowitz and Helke, 1980Kummer et al, 1989bKusakabe et al, 1998a Vasoactive intestinal polypeptide (VIP) Cat Wharton et al, 1980Grimes et al, 1995…”