Vasopressin in the brain maintains size of vasopressin neurons even when body fluid becomes more diluted

Preventing the vasopressin neurons from swelling, and maintaining their size

The anti-diuretic hormone "vasopressin" is released from the brain, and known to work in the kidney, suppressing the diuresis. Here, the Japanese research team led by Professor Yasunobu OKADA, Director-General of National Institute for Physiological Sciences (NIPS), and Ms. Kaori SATO, a graduate student of The Graduate University for Advanced Studies, clarified the novel function of "vasopressin" that works in the brain, as well as in the kidney via the same type of the vasopressin receptor, to maintain the size of the vasopressin neurons. It might be a useful result for clarification of the condition of cerebral edema which swells along with the brain trauma or the cerebral infarction, and for its treatment method development. This result of the study is reported in the Science Signaling magazine (issue on January 25, 2011) which is the offshoot of Science magazine published by American Association for the Advancement of Science (AAAS).

The research team focused on the vasopressin neurons which exist in a hypothalamus of the brain. The vasopressin is essentially released from the vasopressin neurons into blood circulation and acts on the kidney as anti-diuretic, when the blood plasma becomes more concentrated. In contrast, they ascertained that the vasopressin neurons release the vasopressin into the brain, not in blood, when the surrounding body fluid becomes more diluted than usual. Usually, the more diluted the body fluid becomes, the bigger the neuronal cell swells. However, their finding shows that the vasopressin in the brain maintains the size of the vasopressin neurons even when the body fluid becomes more diluted. In addition, it was clarified that the vasopressin sensor protein (receptor) which was currently considered to be only in the kidney, was related to this function in the brain.

This study became possible by labeling vasopressin neurons of the rat brain hypothalamus with green fluorescent protein (GFP)．(The transgenic rat was developed by Professor Yoichi UETA; University of Occupational and Environmental Health, Japan)

Professor OKADA says that "It is a surprising result that the same type of the vasopressin receptor as the kidney exists in the brain and the vasopressin works on it. It can be expected to clarify the condition of cerebral edema which swells along with the brain trauma or the cerebral infarction, and to develop its treatment method.