Plasticity of secretory neurons in the supraoptic and paraventricular nuclei of the hypothalamus on exposure to light
Light and electron microscopic methods were used to analyze changes in secretory neurons in the supraoptic (SON) and paraventricular (PVN) nuclei in the hypothalamus in 100 adult male rats at time points from the first minutes to 180 days after 48 hours of full-time exposure to bright light. At the early time points after exposure, the cellular formulae of the SON and PVN shifted towards functionally active neurons with minimal quantities of secretory granules, large nuclei and nucleoli, low RNA contents, small numbers of rough endoplasmic reticulum cisterns, vacuoles, and lysosomes in the perikarya. The number of cells depositing secretion was greater than in controls at 24 h in the SON and PVN and at 10 days in the SON. Normalization of the cellular formula and the structural organization of the protein-synthesizing apparatus of PVN neurons occurred at 10–30 days, with normalization in the SON at 30–180 days. These data provide evidence that the range of plasticity of neurons in the PVN on exposure to full-time bright light was more significant than that in the SON.
Key wordshypothalamus magnocellular nuclei secretory neurons light
Unable to display preview. Download preview PDF.
- 1.I. G. Akmaev, “Current concepts of the interaction of the hypothalamic neurosecretory and autonomic nervous systems in the regulation of endocrine and homeostatic functions,” Morfologiya, 102, No. 3, 5–39 (1992).Google Scholar
- 2.B. V. Aleshin, Histophysiology of the Hypothalamo-Hypophyseal System [in Russian], Meditsina, Moscow (1971).Google Scholar
- 3.A. V. Gerasimov, “Functional morphology of neurons in the suprachiasmatic nuclei of the rat hypothalamus after combined exposure to x-rays and light,” Radiats. Biol., 43, No. 4, 389–395 (2003).Google Scholar
- 4.S. V. Logvinov, A. V. Gerasimov, and V. P. Kostyuchenko, “Structural changes in epitheliocytes of granular output streams and terminal regions of the submandibular glands in rats on exposure to light and radiation,” Morfologiya, 124, No. 4, 80–83 (2003).Google Scholar
- 5.A. L. Polenov, Hypothalamic Neurosecretion [in Russian], Nauka, Leningrad (1968).Google Scholar
- 9.Y. Hosoya, Y. Suqiura, R. Ito, and K. Kohno, “Descending projections from the hypothalamic paraventricular nucleus to the A 5 area, including the superior salivatory nucleus, in the rat,” Exptl. Brain Res., 82, No. 3, 513–518 (1990).Google Scholar