Suka Ayaka, Uenoyama Reiko, Ichizawa Shota, Katayama Masaaki, Miyazaki Masao, Miyazaki Tamako
Division of Agriculture, Graduate School of Arts and Sciences, Iwate University, Iwate, Japan.
Department of Bioresources Science, The United Graduate School of Agricultural Sciences, Iwate University, Iwate, Japan.
J Vet Med Sci. 2025 Jan 10;87(1):61-67. doi: 10.1292/jvms.24-0370. Epub 2024 Dec 3.
Cats with progressive renal diseases often exhibit a weakened urinary odor, in contrast to normal cat urine which emits odorants with catty odor, such as 3-mercapto-3-methyl-1-butanol, 3-mercapto-3-methylbutyl formate, 3-methyl-3-methylthio-1-butanol, and 3-methyl-3-(2-methyldisulfanyl)-1-butanol. Felinine, an amino acid, is a precursor of these odorants and metabolized from its precursor, 3-methylbutanol glutathione (MBG), via 3-methylbutanol-cysteinylglycine (MBCG). While previous studies have reported felinine excretion in normal cats, its levels in cats with renal diseases remain unclear. This study investigates the urinary excretion of felinine and its precursors in cats with renal diseases and explores whether changes in these metabolites are linked to reduced volatile felinine derivatives with catty odor. Liquid chromatography/mass spectrometry quantified urinary felinine, MBCG, and MBG in 40 normal cats and 66 cats with renal diseases (classified into mild, moderate, and severe renal diseases), revealing a significant decrease in urinary felinine levels in cats with advanced renal disease, while urinary MBG levels increased. The felinine-to-MBG ratio was significantly lower in cats with severe renal disease compared to normal cats and those with mild renal disease. Gas chromatography/mass spectrometry analysis further showed that the emission of felinine derivatives decreased markedly with renal disease progression. A significant correlation was found between urinary felinine excretion and its major derivative, 3-methyl-3-methylthio-1-butanol. These findings suggest that impaired felinine metabolism, likely due to reduced kidney enzyme activity, contributes to both diminished urinary felinine levels and reduced sulfurous odor in cats with renal diseases.
与正常猫尿会散发如3-巯基-3-甲基-1-丁醇、甲酸3-巯基-3-甲基丁酯、3-甲基-3-甲硫基-1-丁醇和3-甲基-3-(2-甲基二硫烷基)-1-丁醇等带有猫尿气味的气味剂不同，患有进行性肾脏疾病的猫尿液气味往往较弱。猫氨酸是一种氨基酸，是这些气味剂的前体，它由其前体3-甲基丁醇谷胱甘肽（MBG）经3-甲基丁醇-半胱氨酰甘氨酸（MBCG）代谢而来。虽然此前的研究报道了正常猫体内猫氨酸的排泄情况，但其在患有肾脏疾病的猫体内的水平仍不清楚。本研究调查了患有肾脏疾病的猫尿液中猫氨酸及其前体的排泄情况，并探讨这些代谢物的变化是否与挥发性猫尿气味的猫氨酸衍生物减少有关。液相色谱/质谱法定量分析了40只正常猫和66只患有肾脏疾病的猫（分为轻度、中度和重度肾脏疾病）尿液中的猫氨酸、MBCG和MBG，结果显示晚期肾脏疾病猫的尿液猫氨酸水平显著降低，而尿液MBG水平升高。与正常猫和轻度肾脏疾病猫相比，重度肾脏疾病猫的猫氨酸与MBG比值显著更低。气相色谱/质谱分析进一步表明，随着肾脏疾病进展，猫氨酸衍生物的散发显著减少。尿液猫氨酸排泄与其主要衍生物3-甲基-3-甲硫基-1-丁醇之间存在显著相关性。这些发现表明，猫氨酸代谢受损，可能是由于肾脏酶活性降低，导致患有肾脏疾病的猫尿液中猫氨酸水平降低和含硫气味减少。
