Endocrine Abstracts

Vasopressin (VP) and oxytocin (OT), the antidiuretic and natriuretic hormone, respectively, maintain the osmotic homeostasis. These molecules are synthesized in the magnocellular neurons (MCNs) of the supraoptic nuclei (SON) in the hypothalamus, transported via the axons toward the neural lobe of hypophysis (NLH) and released into the blood stream.

Dp71 is the major form of dystrophins in the SON and NLH, where it was located in the glial-end-feet and endothelial cell. To clarify Dp71’s involvement in SON and NLN response to osmotic stimulus, we examined the effect of Dp71 disruption on the VP and OT synthesis in SON and release from NLH before and after salt-loading (SL).

In Dp71-null mice, SL increased VP-mRNA and VP-peptide, although this increase was smaller than that observed in WT. It is associated with an increase in VP export, insofar as the VP content was reduced in the SON of SL-Dp71-null mice, and the same pattern was observed in the NLH.

OT-mRNA and OT-peptide were more intense in SON of Dp71-null than in SON of WT before SL. SL increased OT-mRNA and OT-peptide in SON of WT but had no effect on those of Dp71-null. In the NLH, before SL, OT was lower in Dp71-null than in wild-type, and under SL, OT decreased in NLH of WT but not in that of Dp71-null.

To return to the pathology, recent studies described symptomatic nephrolithiasis in Duchenne muscular dystrophy patients. One of the origins of stone disease is a reduction in urinary volume. This could be the consequence of a change in the capacity of the SON and NLN to react to osmotic changes resulting from the disruption of dystrophin.

Key Words: dp71, vasopressin, ocytocin, supraoptic nucleuc, neural lobe, osmoregulation