Activation of vasopressinergic and oxytocinergic neurons during aging in the Wistar rat.
The activity of the hypothalamo-neurohypophyseal system (HNS) was determined in male Wistar rats from 3 to 32 months of age. Plasma levels of vasopressin (AVP) and oxytocin (OXT) were measured by means of a radioimmunoassay. In addition, the distribution of the Golgi apparatus marker enzyme thiamine-pyrophosphatase (TPP-ase) was measured as a parameter for neurosecretory activity in the hypothalamic supraoptic and paraventricular nuclei (SON and PVN). Plasma levels of radioimmunoassayable AVP were increased in the 32-month-old animals. Plasma levels of radioimmunoassayable OXT in 32-month-old animals did not differ from the levels found in the youngest group, but were higher than in 11-month-old animals. Neurosecretory activity in the SON was similar in 3- and 32-month-old animals, whereas in the PVN neurosecretory activity was increased in the 32-month-old animals. Urine excretion decreased between 6 and 11 months of age and remained on the same level until 32 months of age. In other words, instead of a loss of HNS function as has been suggested in the literature, an increased neurosecretory activity was observed in aged rats.
D000375:Aging; D000818:Animals; D001127:Arginine Vasopressin / Q000097:blood / Q000378:metabolism*; D001835:Body Weight; D001921:Brain / Q000254:growth & development; D007030:Hypothalamo-Hypophyseal System / Q000254:growth & development*; D008297:Male; D009474:Neurons / Q000502:physiology*; D009929:Organ Size; D010121:Oxytocin / Q000097:blood / Q000378:metabolism*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D014556:Urine
D001127:Arginine Vasopressin; D010121:Oxytocin