Protirelin

Thyrotropin-releasing hormone (TRH) stimulation can be used as a test of thyroid function and pituitary thyrotropin (thyroid-stimulating hormone, TSH) reserve, but optimal stimulation testing protocols in cats are unreported. We randomly divided 6 healthy young adult cats into 3 groups of 2 and administered 3 different intravenous doses of TRH (0.01, 0.05, 0.1 mg/kg) at weekly intervals in our crossover study. Serum TSH and thyroxine (T4) concentrations were measured using chemiluminescent immunoassay before, and at 30 and 60 min after, TRH administration. All cats were monitored for 4 h post-TRH administration for side effects. All 3 TRH doses induced significant TSH (0.01 mg/kg, p  = 0.001; 0.05 mg/kg, p = 0.002; 0.1 mg/kg, p  = 0.006) and total T4 (0.01 mg/kg, p  = 0.008; 0.05 mg/kg, p = 0.006; 0.1 mg/kg, p  = 0.001) responses. Lower TRH doses (0.01 and 0.05 mg/kg) caused fewer side effects (1 of 6 cats) than did the highest dose (3 of 6 cats), and may be safer in cats than the previously reported higher dose (0.1 mg/kg) of TRH. Our results do not support the use of maropitant to prevent side effects of a TRH stimulation test in cats.

Sensitive and discriminative sensing of more than one analyte with a single fluorescent probe is significant and challenging. Herein a new terpyridyl-rhodamine hybrid, namely TRH, has been rationally designed and prepared with two responsive groups in the molecular structure, which facilitate the discriminative detection of Hg²⁺ and Cu²⁺ ions in water with detection limits of 4.9 and 53.3 nM by ratiometric fluorescence change (F₅₉₅/F₄₈₅) and fluorescence quenching, respectively. Investigations show that the selectivity to Hg²⁺ ions can be attributed to Hg²⁺-promoted spirolactam ring opening and further hydrolysis, followed by a through-bond energy transfer (TBET) process. The selective fluorescence quenching to Cu²⁺ ions probably can be ascribed to the binding Cu²⁺ to terpyridyl that triggers a ligand-to-metal charge transfer (LMCT) process, which can also efficiently inhibit the TBET process induced by Hg²⁺ ions and promotes the discriminative sensing of Cu (II) and Hg (II). In addition, the fluorescent responses to Hg²⁺ and Cu²⁺ ions cover a wide pH range. Moreover, a combinatorial logic gate with the functions of NOR and INHIBIT has been fabricated by using Hg²⁺ and Cu²⁺ ions as chemical input signals, and fluorescence at 485 and 595 nm as output signals. Besides, TRH also exhibits sensitive and discriminative sensing ability to Hg²⁺ and Cu²⁺ ions by the fluorescence of rhodamine fluorophore. Significantly, based on the fluorescence signal output of rhodamine moiety, TRH can be used as a tracer for the discriminative sensing of Hg²⁺ and Cu²⁺ ions by using living cells.