Next, to further investigate ANG II’s effects on taste sensitivities, behavioral responses to taste stimuli after administration of ANG II were examined by using a short-term lick test, which quantifies immediate lick responses (per 10 s) to reduce post-ingestive effects, by using 23 h water deprived mice because it is relatively easy to maintain motivation and provides a larger amount of data in a short test period [50], [51] and [52]. Numbers of licks per 10 s for distilled water (DW) and sweeteners at various concentrations are typically similar, within

a range of about 65–80, whereas VX-809 price lick numbers for 0.3–1.0 mM QHCl are around 15. To more clearly detect concentration-dependent changes in lick rates for sweeteners, mixtures of 0.5 mM QHCl and sweeteners were used as test solutions (a sweet-bitter mixture paradigm) Alisertib [50], [51] and [52]. In

the results, ANG II did not affect the lick rates for NaCl and sucrose in mice. Previous studies showed that 23–48 h water deprivation induces elevation in circulating levels of endogenous ANG II [53] and [54], suggesting effects of the exogenous ANG II on behavioral taste responses would be weakened or not obvious in these 23 h water deprived mice. Thus, the effects of CV11974 on behavioral taste responses were tested. The behavioral tests showed that lick rates for NaCl (amiloride-sensitive) and sweeteners, but not for KCl, sour, bitter or umami substances, were significantly reduced by pretreatment with CV11974. These results demonstrated that the sodium inhibition and sweet enhancement by ANG II on gustatory nerve responses critically influences ingestive behaviors for sodium (amiloride-sensitive) and

sweeteners [48]. The taste crotamiton bud contains at least three morphologically distinct cell types (I–III) in both fungiform and circumvallate papillae [55]. Type I cells express a glial glutamate transporter (GLAST) [56] and an ecto-ATPase (Entpd2) [57], and extend lamellate processes around other types of taste cells. These features suggest that Type I cells function like as glial cells (e.g. transmitter clearance or functional isolation of other taste cell types). Type II cells express GPCRs, taste receptor type 1 (T1r) and type 2 (T2r) families of taste receptors (T1r2 + T1r3 heterodimer for sweet, T1r1 + T1r3 heterodimer for umami and T2rs for bitter) [58], [59], [60], [61], [62], [63] and [64], and all of the molecules of the common transduction cascade downstream of these taste receptors, which are Gα-gustducin [65], phospholipase C β2 (PLCβ2), inositol 1,4,5-trisphosphate receptor type 3 (IP3R3) [66] and [67] and Trpm5 [68], [69] and [70]. Type II cells do not have conventional synapses based on ultrastructural criteria.