Plasticity of secretory neurons in the supraoptic and paraventricular nuclei of the hypothalamus on exposure to light

Abstract

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.

The istant changes of the salivary glands to stress

“…Круглосуточное освещение морских свинок, ведущих активный дневной образ жизни, и крыс, проявляющих большую активность ночью, нарушает суточный ритм как циркадианных пейсмекеров -нейроэндокринных центров, так и слюнных желез [5,6,8]. Известно, что исчерченные и гранулярные отделы выводных протоков, вырабатывающие биологически активные вещества белковой природы, ответственны за эндокринные функции поднижнечелюстных желез грызунов.…”

Effect of Long-Term Constant Illumination of Female Rats on the Parameters of Brain Development in Their 40-Day-Old Progeny

“…Morphofunctional state of the gland returns to normal only 30 days after exposure [3]. In the progeny of rats maintained under constant illumination starting from day 17 of pregnancy, the number of light pinealocytes and total protein content in secretory cells of the pineal gland decreased [1].…”