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“Diabetes Insipidus” Strain Quail Show Poorly Developed Medullary Cones and Low Aquaporin 2 Water Channel Expression
Author(s) -
YANG YIMU,
Minvielle Francis,
Kuykindoll Rhonda J,
Gasc JeanMarie,
Yamamoto Tadashi,
Nishimura Hiroko
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.934.24
Subject(s) - quail , endocrinology , medicine , aquaporin 2 , polyuria , polydipsia , biology , diabetes insipidus , nephrogenic diabetes insipidus , diabetes mellitus , water channel , mechanical engineering , engineering , inlet
A Coturnix japonica strain with clinical signs of diabetes insipidus (DI) was developed after screening for polydipsia and polyuria (homozygous autosomal recessive mutation with unaffected vasotocin system) (Minvielle et al., Poult Sci 86: 249, 2007). To determine the mechanism behind DI manifestation, we examined kidney morphology, molecular expression of AQP2 water channels, and responses to water restriction. DI quail kidneys have poorly developed medullary cones with a significantly ( P < 0.01) smaller area per kidney (longitudinal section) (control, CT, 14.7 ± 1.0%; DI, 8.9 ± 1.1%); the number of glomeruli is similar in CT and DI quail. The DI and CT gene and amino acid sequences are nearly identical, including two NPA motifs, a mercury‐sensitive structure, and a putative phosphorylation site. AQP2 mRNA levels measured by in situ riboprobe hybridization and real‐time PCR are low in DI quail. Hematocrit (Hct, %) and plasma osmolality (P osm , mOsmol/l) are also lower (Hct, 42 ± 1; P osm , 297 ± 11) than in CT quail (Hct, 47 ± 1; P osm , 322 ± 3); both increased after 24 h water restriction in DI and CT groups, but DI quail lost more body weight. The results suggest that the renal medulla plays a major role in causing DI manifestation. The mechanism of possible blood volume expansion remains to be elucidated (NSF IOB‐0615359, NIH HL52881).