Serotonin via 5‐HT<sub>1B</sub> and 5‐HT<sub>2B</sub> receptors stimulates anion secretion in the rat epididymal epithelium

Leung, George Pak-Heng; Dun, S.L.; Dun, Nae J.; Wong, Patrick

doi:10.1111/j.1469-7793.1999.0657n.x

Cited by 32 publications

(27 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Cultured rat epididymal epithelia have been used as a model to study transepithelial secretion of electrolytes in the epididymis [10]. When stimulated with exogenous cAMP or cAMP-elevating agonists, these epithelia respond by an increase in electrogenic chloride secretion (measured as short-circuit current, Isc) [17,18] that can be blocked by putative chloride channel blockers, such as the arylaminobenzoates and sulfonylureas [19]. In this study, apically applied lonidamine and AF2785 were found to inhibit the cAMP-induced short-circuit current (Fig.…”

Section: Discussionmentioning

confidence: 99%

Lonidamine and Analogue AF2785 Block the Cyclic Adenosine 3′,5′-Monophosphate-Activated Chloride Current and Chloride Secretion in the Rat Epididymis1

Gong

Wong

Leung

et al. 2000

Biology of Reproduction

View full text Add to dashboard Cite

The cystic fibrosis transmembrane conductance regulator (CFTR) or the small conductance cAMP-activated chloride channel encoded by the CFTR gene has been shown to play an important role in the formation of the epididymal fluid microenvironment. Mutation of the gene has led to widespread effects on male reproduction. Like other ion channels, CFTR is amenable to pharmacological intervention. Blocking CFTR in the epididymis could in principle lead to disruption of the epididymal fluid environment. We report for the first time two indazole compounds: lonidamine and 1-(2, 4-dichlorobenzyl)-indazole-3-acrylic acid (AF2785) are potent blockers of CFTR in the epididymis. When added to the external solution under whole-cell patch clamp conditions, AF2785 and lonidamine inhibited the cAMP-activated chloride current in rat epididymal cells with apparent IC(50) values of 170.6 and 631.5 microM, respectively; by comparison the IC(50) value for diphenylamine-2-carboxylate, a well-known chloride channel blocker was 1294 microM. In cultured rat epididymal epithelia mounted in a Ussing chamber, AF2785 and lonidamine inhibited the cAMP-stimulated short-circuit current (a measure of chloride secretion) when added to the apical bathing solution with potency greater than any known chloride channel studied. It is proposed that in view of the important role CFTR plays in male reproduction, further study with these and other new indazole compounds for their CFTR blocking actions can provide a new avenue of research into the development of novel male contraceptives.

show abstract

Section: Discussionmentioning

confidence: 99%

Lonidamine and Analogue AF2785 Block the Cyclic Adenosine 3′,5′-Monophosphate-Activated Chloride Current and Chloride Secretion in the Rat Epididymis1

Gong

Wong

Leung

et al. 2000

Biology of Reproduction

View full text Add to dashboard Cite

show abstract

“…In the guinea pig distal colon, 5-HT at 0.1-1 µM stimulated Cl -transport via cholinergic nerves (21,22). Direct stimulation of epithelial Cl -transport by 5-HT was observed at 0.05-1 µM in rat choroid plexus (23), at 1-100 µM in rat trachea (24), and at 0.1-1 µM in rat epididymis (25).…”

Section: -Ht-containing Cells In the Guinea Pig Pancreasmentioning

confidence: 98%

5-hydroxytryptamine strongly inhibits fluid secretion in guinea pig pancreatic duct cells

Suzuki¹,

Naruse²,

Kitagawa³

et al. 2001

J. Clin. Invest.

View full text Add to dashboard Cite

IntroductionThe gastrointestinal tract is the major source of serotonin, 5-hydroxytryptamine (5-HT); a large amount of 5-HT is concentrated in the enterochromaffin (EC) cells and the submucosal and myenteric neurons (1, 2). Mechanical distension of the intestinal mucosa and a variety of neurohormonal stimuli have been shown to release 5-HT from the EC cells mainly into the interstitial space (3), but also into the gut lumen (4, 5). The released 5-HT binds various subtypes of 5-HT receptors on enteric neurons, smooth muscle cells, and epithelial cells and regulates intestinal fluid transport and peristalsis (2,4,6).In the pancreas, 5-HT is mainly present in β cells of the islet of Langerhans (7,8) and in serotonergic pancreatic nerve fibers (2, 9). The presence of the EC cells in the exocrine pancreas has also been noticed but their exact localization and function have not been described (8). In the present investigation we examined the distribution of the EC cells in the guinea pig pancreas by immunohistochemical methods and found that they were present throughout the pancreatic duct system. To understand a regulatory function of the EC cells on the neighboring duct cells, we examined the effect of 5-HT on the isolated pancreatic ducts, where the functions of the pancreatic duct in vivo are well preserved (10). MethodsThe following study was approved by the Ethical Committee of Nagoya University on Animal Use for Experiment.Immunohistochemistry. Under anesthesia with pentobarbital, female Hartley guinea pigs (300-350 g) were killed by intracardiac perfusion with Ringer's solution for 1 minute followed by 4% paraformaldehyde for 10 minutes, as described previously (11). The dissected specimens of the pancreas were further dipped in the fixative overnight. They were cryoprotected in graded concentration of sucrose, embedded in OCT compounds, and then frozen. Sections of 4-µm thickness were cut by a cryostat and mounted on albumin-coated glass slides. Endogenous peroxidase activity of the sections was blocked with 0.3% H 2 O 2 in methanol for 30 minutes at room temperature. The section was incubated with 10% normal goat serum for 30 minutes and then with mouse anti-serotonin mAb (clone 5HT-H209, 1:200 dilution) for 1-2 days at 4°C. It was then incubated with biotinylated anti-mouse IgG (1:200) at room temperature for 2 hours followed by the avidin-biotin-peroxidase complex for 2 hours. The immunoreaction was visualized by 0.02% diaminobenzidine tetrahydrochloride in 0.05 M Tris-HCl containing 0.01% H 2 O 2 and was examined with an interference contrast microscope (Olympus AX; Olympus Optical Co., Tokyo, Japan). We studied the distribution of 5-hydroxytryptamine-(5-HT-) containing cells in the guinea pig pancreas and examined the effects of 5-HT on fluid secretion by interlobular pancreatic ducts. The 5-HT-immunoreactive cells with morphological characteristics of enterochromaffin (EC) cells were scattered throughout the duct system and were enriched in islets of Langerhans. The fluid secretory rate in the isolated ...

show abstract

“…We have studied the role of CFTR in anion and fluid secretion in our laboratory and have found that a variety of neurohumoral agents [4][5][6][7] regulate anion secretion via CFTR activation. These effects may have an important influence on the formation of epididymal fluid.…”

Section: Introductionmentioning

confidence: 99%

Indazole Inhibition of Cystic Fibrosis Transmembrane Conductance Regulator Cl− Channels in Rat Epididymal Epithelial Cells1

Gong

Linsdell

Cheung

et al. 2002

Biology of Reproduction

View full text Add to dashboard Cite

Previous studies have shown that two indazole compounds, lonidamine [1-(2,4-dichlorobenzyl)-indazole-3-carboxylic acid] and its analogue AF2785 [(1-(2,4-dichlorobenzyl)-indazol-3-acrylic acid], suppress fertility in male rats. We also found that these compounds inhibit the cystic fibrosis transmembrane conductance regulator chloride (CFTR-Cl(-)) current in epididymal epithelial cells. To further investigate how lonidamine and AF2785 inhibit the current, we used a spectral analysis protocol to study whole-cell CFTR current variance. Application of lonidamine or AF2785 to the extracellular membrane of rat epididymal epithelial cells introduced a new component to the whole-cell current variance. Spectral analysis of this variance suggested a block at a rate of 3.68 micro mol(-1)/sec(-1) and an off rate of 69.01 sec(-1) for lonidamine, and an on rate of 3.27 micro mol(-1)/sec(-1) and an off rate of 108 sec(-1) for AF2785. Single CFTR-Cl(-) channel activity using excised inside-out membrane patches from rat epididymal epithelial cells revealed that addition of lonidamine to the intracellular solution caused a flickery block (a reduction in channel-open time) at lower concentration (10 micro M) without any effect on open channel probability or single-channel current amplitude. At higher concentrations (50 and 100 micro M), lonidamine showed a flickery block and a decrease in open-channel probability. The flickery block by lonidamine was both voltage-dependent and concentration-dependent. These results suggest that lonidamine and AF2785, which are open-channel blockers of CFTR at low concentrations, also affect CFTR gating at high concentrations. We conclude that these indazole compounds provide new pharmacological tools for the investigation of CFTR. By virtue of their interference with reproductive processes, these drugs have the potential for being developed into novel male contraceptives.

show abstract

Serotonin via 5‐HT_1B and 5‐HT_2B receptors stimulates anion secretion in the rat epididymal epithelium

Cited by 32 publications

References 35 publications

Lonidamine and Analogue AF2785 Block the Cyclic Adenosine 3′,5′-Monophosphate-Activated Chloride Current and Chloride Secretion in the Rat Epididymis1

Lonidamine and Analogue AF2785 Block the Cyclic Adenosine 3′,5′-Monophosphate-Activated Chloride Current and Chloride Secretion in the Rat Epididymis1

5-hydroxytryptamine strongly inhibits fluid secretion in guinea pig pancreatic duct cells

Indazole Inhibition of Cystic Fibrosis Transmembrane Conductance Regulator Cl− Channels in Rat Epididymal Epithelial Cells1

Contact Info

Product

Resources

About

Serotonin via 5‐HT1B and 5‐HT2B receptors stimulates anion secretion in the rat epididymal epithelium

Cited by 32 publications

References 35 publications

Lonidamine and Analogue AF2785 Block the Cyclic Adenosine 3′,5′-Monophosphate-Activated Chloride Current and Chloride Secretion in the Rat Epididymis1

Lonidamine and Analogue AF2785 Block the Cyclic Adenosine 3′,5′-Monophosphate-Activated Chloride Current and Chloride Secretion in the Rat Epididymis1

5-hydroxytryptamine strongly inhibits fluid secretion in guinea pig pancreatic duct cells

Indazole Inhibition of Cystic Fibrosis Transmembrane Conductance Regulator Cl− Channels in Rat Epididymal Epithelial Cells1

Contact Info

Product

Resources

About

Serotonin via 5‐HT_1B and 5‐HT_2B receptors stimulates anion secretion in the rat epididymal epithelium