ULTRASTRUCTURAL-CHANGES IN THE HYPOTHALAMIC PARAVENTRICULAR NUCLEUS OF THE STREPTOZOTOCIN-INDUCED DIABETIC RAT

This study describes the ultrastructural and morphometric changes in t he hypothalamic paraventricular nucleus (PVN) of the streptozotocin-in duced diabetic rat. During the acute phase (3 days after induction of diabetes), dendrites were swollen and appeared to have a watery cytopl asm. The affected dendrites were postsynaptic to seemingly normal axon terminals. During the intermediate phase (1-9 months after induction of diabetes), the neuronal somata contained numerous vacuoles of vario us sizes which were probably formed from dilated rough endoplasmic ret iculum. Several unidentifiable vacuolated profiles were also seen in t he neuropil. During the late phase (12 months after induction of diabe tes) electron-dense dendrites and axon terminals were readily encounte red in the neuropil. Most of the electron-dense dendrites were postsyn aptic to normal as well as electron-dense axon terminals. Some of the electron-dense axon terminals formed axosomatic synapses with seemingl y normal somata. Perivascular glial cells in the neuropil were in the process of phagocytosis. At 1-12 months of diabetes, the sizes of the somata and nuclei of PVN neurons were significantly increased in compa rison with age-matched control rats.