Identification and regional distribution of the dopamine D_1A receptor in the gastrointestinal tract

Abstract

Dopamine (DA) is regarded as an important modulator of enteric function. Recent experiments have suggested that newly cloned DA receptor subtypes are widely expressed in peripheral organs, including the gastrointestinal tract. In the present studies, the D(1A) receptor subtype was identified in rat gut regions through localization of receptor protein by means of light microscopic immunohistochemistry and Western blot analysis and receptor mRNA by RT-PCR and in situ amplification and hybridization (3SR in situ). D(1A) receptor immunoreactivity was shown to have a diverse distribution in the gastrointestinal tract, being present in the gastroesophageal junction, stomach, pylorus, small intestine, and colon. The receptor has a transmural distribution present in both epithelial and muscle layers as well as in blood vessels and lamina propria cells of different gastrointestinal regions. Western blot analysis demonstrated a single 50-kDa band for esophagus, stomach, duodenum, jejunum, and colon. The in situ hybridization signal was localized to the same sites revealed by D(1A) receptor immunoreactivity. RT-PCR revealed an appropriate sized signal in similar regions. This study is the first to identify expression of the central D(1A) receptor throughout the normal mammalian gastrointestinal tract.

β-Adrenoceptors, but not dopamine receptors, mediate dopamine-induced ion transport in late distal colon of rats

“…The dopaminergic receptor has also been found in peripheral organs, including the gastrointestinal tract (Vaughan et al 2000;Li et al 2006). However, whether dopaminergic receptor(s) mediates dopamineinduced ion transport in rat late distal colon is not clear.…”

“…Inhibition of adenylate cyclase via D 2 -like receptors causes a reduction of intracellular cAMP (Missale et al 1998). Dopamine D 1A receptor has a transmural distribution in the colon (Vaughan et al 2000). D 2 receptor has not been found in the epithelium of the mouse distal colon (Li et al 2006).…”

Simultaneous absence of dopamine D1 and D2 receptor-mediated signaling is lethal in mice

“…D1r and D2r expression has been reported in the GI tract; D1r was found in the lamina propria submucosal vessels as well as smooth muscle cell layers (40,41), whereas D2r was found in the myenteric ganglia (41), where TH and DA transporter (DAT) are also expressed (42). Lack of DAT results in hyperdopaminergia and altered regulation of colonic motility (43).…”

Role of CAMKII in reinforcement learning: a computational model of glutamate and dopamine signaling pathways

“…At present, two members of the D1 receptor family have been described, the D1A and D1B (D5 human equivalent) receptors, along with three members of the D2 family, the D2, D3, and D4 receptors (Vaughan et al 2000). Out of five type of DA receptors D1, D5 are excitatory and D2, D3, and D4 are inhibitory receptors.…”

“…The D1 receptors are classified as D1A and D1B receptors based on their state of affinity. D1B receptors, which are also called D5 receptors, are high affinity receptors (Tumova et al 2003;Vaughan et al 2000;Glausier et al 2009). The D1A receptors are low affinity receptors.…”