The effect of fasting and refeeding on the ultrastructure of the hypothalamic paraventricular nucleus in young and old rats
2004
In order to explore the morphological basis of the altered feeding behaviour of
old rats, an ultrastructural investigation of the magnocellular neurons of the
hypothalamic paraventricular nucleus (PVN) was performed. Young and old male
Wistar rats, 5 and 24 months old, respectively, and with each age group comprising
12 animals, were divided into 3 groups. The rats in Group I were used as
controls (normally fed), the rats of Group II were fasted for 48 hours and in
Group III the rats were fasted for 48 hours and then refed for 24 hours. The
brains were fixed by perfusion and histological and ultrathin sections were obtained
by routine methods. Common features of the magnocellular PVN neurons
of young and old rats were abundant Golgi complexes and short fragments
of RER localised at the cell periphery. In contrast to young rats, the PVN neurons
of old animals showed deep indentations of the nuclear envelope and agerelated
residual bodies. In both age groups fasting for 48 hours led to the expansion
of the Golgi complexes and dilatation of RER cisternae. In contrast to
those in fed rats, RER cisternae in the neurons of old fasted animals were situated
between the nuclear envelope and the Golgi zone. Prolonged RER cisternae
were distributed in the peripheral cytoplasm of refed old rats. Our observations
suggest that at the ultrastructural level the process of ageing does not change
the responsiveness of magnocellular PVN neurons to fasting-refeeding.
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