Tachykinin receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

Tachykinin receptors (provisional nomenclature as recommended by NC-IUPHAR [90]) are activated by the endogenous peptides substance P (SP), neurokinin A (NKA; previously known as substance K, neurokinin α, neuromedin L), neurokinin B (NKB; previously known as neurokinin β, neuromedin K), neuropeptide K and neuropeptide γ (N-terminally extended forms of neurokinin A). The neurokinins (A and B) are mammalian members of the tachykinin family, which includes peptides of mammalian and nonmammalian origin containing the consensus sequence: Phe-x-Gly-Leu-Met. Marked species differences in in vitro pharmacology exist for all three receptors, in the context of nonpeptide ligands. Antagonists such as aprepitant and fosaprepitant were approved by FDA and EMA, in combination with other antiemetic agents, for the prevention of nausea and vomiting associated with emetogenic cancer chemotherapy.

Predominant expression of type-VI adenylate cyclase in C6-2B rat glioma cells may account for inhibition of cyclic AMP accumulation by calcium

In C6-2B cells, agonist-stimulated cyclic AMP accumulation is inhibited when the cytosolic Ca2+ concentration is increased. We now demonstrate that in C6-2B cells: (i) the early kinetics of the cyclic AMP inhibition by substance K (t1/2 = 35 s) and thapsigargin (t1/2 = 1.6 min) closely mimic the kinetics of the cytosolic Ca2+ increase evoked by either agent (t1/2 = 25 s and 1.5 min respectively); (ii) the Ca2+ rise and cyclic AMP inhibition by substance K or thapsigargin are similarly affected in EGTA-containing medium; (iii) PCR detects type-III and type-VI adenylate cyclase cDNAs, and RNAase protection assays show that the mRNA for type-VI adenylate cyclase, an isoform inhibitable by submicromolar Ca2+ concentrations, is the predominant species, strongly suggesting that type-VI adenylate cyclase is probably the target molecule for Ca(2+)-mediated inhibition of cyclic AMP accumulation.