UNCHANGED AMOUNTS OF VASOPRESSIN MESSENGER-RNA IN THE SUPRAOPTIC AND PARAVENTRICULAR NUCLEUS DURING AGING AND IN ALZHEIMERS-DISEASE

The paraventricular (PVN) and supraoptic nucleus (SON) demonstrate a s triking stability with respect to cell numbers during aging and Alzhei mer's disease (AD). Vasopressin (AVP) neurons even become activated du ring aging as judged from several parameters for neuronal activity, su ch as increased AVP plasma levels, enlarged nucleolar as well as cell size and an increased size of the Golgi apparatus in AVP-neurons. The activation possibly occurs as compensation for an age-related loss of AVP-receptors in the kidney. As a specific marker for AVP synthesis, w e used quantitative in situ hybridization and estimated total amounts of AVP-mRNA in the entire SON and PVN of 14 control subjects and 14 AD patients that were matched for age, fixation time, postmortem delay a nd storage time of the tissue in paraffin. Following quantification, n o differences were observed in total amounts of AVP-mRNA in the SON or PVN between young and old controls or between young and old AD patien ts, nor between the entire group of controls and AD patients. A signif icant negative correlation was found between the volume of the AVP-mRN A signal in the AD SON and age while the total amount of mRNA remained the same. This suggests a redistribution of cells or cell compartment s in aging. A significant positive relation in both SON and PVN of AD patients was found between storage time of the paraffin-embedded tissu e and the total amount of AVP-mRNA. A significant positive relation wa s present in the PVN, but not SON between pH of the cerebrospinal flui d, which is a marker for agonal state and the total amount of AVP mRNA . The present unchanged AVP-mRNA levels in SON and PVN confirm earlier observations on the stability of cell numbers in these nuclei in agin g and AD. Although on the basis of other parameters, AVP-mRNA upregula tion was expected, gradual, chronic stimulation over prolonged periods of time may, possibly, induce alternative mechanisms of regulation su ch as changes in translatability or in mRNA stability.