Progressive polyuria without vasopressin neuron loss in a mouse model for familial neurohypophysial diabetes insipidus.

Abstract

Familial neurohypophysial diabetes insipidus (FNDI), an autosomal dominant disorder, is mostly caused by mutations in the gene of neurophysin II (NPII), the carrier protein of arginine vasopressin (AVP). Previous studies suggest that loss of AVP neurons might be the cause of polyuria in FNDI. Here we analyzed knockin mice expressing mutant NPII that causes FNDI in humans. The heterozygous mice manifested progressive polyuria as do patients with FNDI. Immunohistochemical analyses revealed that inclusion bodies that were not immunostained with antibodies for mutant NPII, normal NPII, or AVP were present in the AVP cells in the supraoptic nucleus (SON), and that the size of inclusion bodies gradually increased in parallel with the increases in urine volume. Electron microscopic analyses showed that aggregates existed in the endoplasmic reticulum (ER) as well as in the nucleus of AVP neurons in 1-mo-old heterozygous mice. At 12 mo, dilated ER filled with aggregates occupied the cytoplasm of AVP cells, while few aggregates were found in the nucleus. Analyses with in situ hybridization revealed that expression of AVP mRNA was significantly decreased in the SON in the heterozygous mice compared with that in wild-type mice. Counting cells expressing AVP mRNA in the SON indicated that polyuria had progressed substantially in the absence of neuronal loss. These data suggest that cell death is not the primary cause of polyuria in FNDI, and that the aggregates accumulated in the ER might be involved in the dysfunction of AVP neurons that lead to the progressive polyuria.

• Authors: Masayuki Hayashi, Hiroshi Arima, Noriyuki Ozaki, Yoshiaki Morishita, Maiko Hiroi, Nobuaki Ozaki, Hiroshi Nagasaki, Noriaki Kinoshita, Masatsugu Ueda, Akira Shiota, Yutaka Oiso
• Journal: American journal of physiology. Regulatory, integrative and comparative physiology (Am J Physiol Regul Integr Comp Physiol) Vol. 296 Issue 5 Pg. R1641-9 (May 2009) ISSN: 0363-6119 [Print] United States
• PMID: 19297548 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Nerve Tissue Proteins
• RNA, Messenger
• neuronal pentraxin
• Arginine Vasopressin
• C-Reactive Protein

Topics

• Animals
• Arginine Vasopressin (genetics, metabolism)
• C-Reactive Protein (genetics, metabolism)
• Cell Death
• Diabetes Insipidus, Neurogenic (genetics, metabolism, pathology)
• Disease Models, Animal
• Drinking (physiology)
• Eating (physiology)
• Endoplasmic Reticulum (metabolism)
• Female
• Gene Knock-In Techniques
• Genotype
• Male
• Mice
• Mice, Inbred C57BL
• Mice, Mutant Strains
• Nerve Tissue Proteins (genetics, metabolism)
• Neurons (metabolism, pathology)
• Polyuria (etiology, metabolism, pathology)
• RNA, Messenger (metabolism)
• Supraoptic Nucleus (metabolism)