Cyclic-AMP regulates postnatal development of neural and behavioral responses to NaCl in rats

• Published in: PloS one Vol. 12; no. 2; p. e0171335
• Main Authors: Qian, Jie, Mummalaneni, Shobha, Phan, Tam-Hao T., Heck, Gerard L., DeSimone, John A., West, David, Mahavadi, Sunila, Hojati, Deanna, Murthy, Karnam S., Rhyu, Mee-Ra, Spielman, Andrew I., Özdener, Mehmet Hakan, Lyall, Vijay
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 13.02.2017; Public Library of Science (PLoS)
• Subjects: Adult; Age; Age Factors; Amiloride; Analysis; Animals; Aquaporins; Argipressin; Biology and Life Sciences; Biophysics; Blotting, Western; Cells, Cultured; Chorda tympani; Chorda Tympani Nerve - drug effects; Chorda Tympani Nerve - physiology; Cyclic AMP; Cyclic AMP - analogs & derivatives; Cyclic AMP - metabolism; Cyclic AMP - pharmacology; Deamino Arginine Vasopressin - pharmacology; Electric potential; Epithelial Sodium Channels - genetics; Epithelial Sodium Channels - metabolism; Food Preferences - drug effects; Food Preferences - physiology; Gene expression; Gene Expression - drug effects; Humans; Intracellular; Intravenous administration; Kinases; Mammals; Medicine and Health Sciences; Microscopy, Confocal; Physiology; Rats; Rats, Sprague-Dawley; Receptors, Vasopressin - metabolism; Research and Analysis Methods; Resistance; Reverse Transcriptase Polymerase Chain Reaction; Rodents; Salts; Social Sciences; Sodium; Sodium channels; Sodium chloride; Sodium Chloride - pharmacology; Sodium conductance; Taste; Taste - drug effects; Taste - physiology; Taste Buds - drug effects; Taste Buds - metabolism; Taste Buds - physiology; Taste receptor neurons; Thionucleotides - metabolism; Thionucleotides - pharmacology; Vasopressin; Vasopressin V2 receptors; Vasopressins; Voltage
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0171335

During postnatal development rats demonstrate an age-dependent increase in NaCl chorda tympani (CT) responses and the number of functional apical amiloride-sensitive epithelial Na+ channels (ENaCs) in salt sensing fungiform (FF) taste receptor cells (TRCs). Currently, the intracellular signals that regulate the postnatal development of salt taste have not been identified. We investigated the effect of cAMP, a downstream signal for arginine vasopressin (AVP) action, on the postnatal development of NaCl responses in 19-23 day old rats. ENaC-dependent NaCl CT responses were monitored after lingual application of 8-chlorophenylthio-cAMP (8-CPT-cAMP) under open-circuit conditions and under ±60 mV lingual voltage clamp. Behavioral responses were tested using 2 bottle/24h NaCl preference tests. The effect of [deamino-Cys1, D-Arg8]-vasopressin (dDAVP, a specific V2R agonist) was investigated on ENaC subunit trafficking in rat FF TRCs and on cAMP generation in cultured adult human FF taste cells (HBO cells). Our results show that in 19-23 day old rats, the ENaC-dependent maximum NaCl CT response was a saturating sigmoidal function of 8-CPT-cAMP concentration. 8-CPT-cAMP increased the voltage-sensitivity of the NaCl CT response and the apical Na+ response conductance. Intravenous injections of dDAVP increased ENaC expression and γ-ENaC trafficking from cytosolic compartment to the apical compartment in rat FF TRCs. In HBO cells dDAVP increased intracellular cAMP and cAMP increased trafficking of γ- and δ-ENaC from cytosolic compartment to the apical compartment 10 min post-cAMP treatment. Control 19-23 day old rats were indifferent to NaCl, but showed clear preference for appetitive NaCl concentrations after 8-CPT-cAMP treatment. Relative to adult rats, 14 day old rats demonstrated significantly less V2R antibody binding in circumvallate TRCs. We conclude that an age-dependent increase in V2R expression produces an AVP-induced incremental increase in cAMP that modulates the postnatal increase in TRC ENaC and the neural and behavioral responses to NaCl.