X‐linked nephrogenic diabetes insipidus (X‐NDI) is a rare congenital disease caused by inactivating mutations of the vasopressin type‐2 receptor (AVPR2), characterized by impaired renal concentrating ability, dramatic polyuria, polydipsia and risk of dehydration. The disease, which still lacks a cure, could benefit from the pharmacologic stimulation of other GPCRs, activating the cAMP‐intracellular pathway in the kidney cells expressing the AVPR2. On the basis of our previous studies, we here hypothesized that the β3‐adrenergic receptor could be such an ideal candidate. We evaluated the effect of continuous 24 h stimulation of the β3‐AR with the agonist BRL37344 and assessed the effects on urine output, urine osmolarity, water intake and the abundance and activation of the key renal water and electrolyte transporters, in the mouse model of X‐NDI. Here we demonstrate that the β3‐AR agonism exhibits a potent antidiuretic effect. The strong improvement in symptoms of X‐NDI produced by a single i.p. injection of BRL37344 (1 mg/kg) was limited to 3 h but repeated administrations in the 24 h, mimicking the effect of a slow‐release preparation, promoted a sustained antidiuretic effect, reducing the 24 h urine output by 27%, increasing urine osmolarity by 25% and reducing the water intake by 20%. At the molecular level, we show that BRL37344 acted by increasing the phosphorylation of NKCC2, NCC and AQP2 in the renal cell membrane, thereby increasing electrolytes and water reabsorption in the kidney tubule of X‐NDI mice. Taken together, these data suggest that human β3‐AR agonists might represent an effective possible treatment strategy for X‐NDI.

中文翻译：

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β3-AR 激动剂 BRL37344 可改善 X 连锁肾性尿崩症小鼠模型的主要症状

X连锁肾性尿崩症（X-NDI）是一种罕见的先天性疾病，由加压素2型受体（AVPR2）失活突变引起，其特征是肾脏浓缩能力受损、严重多尿、烦渴和脱水风险。这种疾病仍然缺乏治愈方法，可以从其他 GPCR 的药理刺激中受益，激活表达 AVPR2 的肾细胞中的 cAMP 细胞内通路。根据我们之前的研究，我们假设β3-肾上腺素能受体可能是一个理想的候选者。我们在小鼠模型中评估了激动剂 BRL37344 连续 24 小时刺激 β3-AR 的效果，并评估了对尿量、尿渗透压、水摄入量以及关键肾水和电解质转运蛋白的丰度和激活的影响。 X-NDI。在这里，我们证明 β3-AR 激动剂具有有效的抗利尿作用。单次腹腔注射 BRL37344（1 mg/kg）对 X-NDI 症状的强烈改善仅限于 3 小时，但在 24 小时内重复给药，模仿缓释制剂的效果，促进了持续的抗利尿作用效果，24小时尿量减少27%，尿渗透压增加25%，水摄入量减少20%。在分子水平上，我们发现BRL37344通过增加肾细胞膜中NKCC2、NCC和AQP2的磷酸化来发挥作用，从而增加X-NDI小鼠肾小管中电解质和水的重吸收。综上所述，这些数据表明人类 β3-AR 激动剂可能代表一种有效的 X-NDI 治疗策略。