Oxytocin as a regulator of pineal gland cells secretory activity

Both hypothalamo-hypophyseal complex and pineal gland plays a great role in adaptive reactions on variable conditions of environment. Pineal peptides and melatonin take part in forming of reactions on osmotic and hypoxic influence. Nerve fibres from epithalamic area, limbic system and hypothalamus are revealed in the pineal gland. Some of them are expected to be of oxytocinergic nature. Formerly we discovered that intraventricular injections of oxytocin (OT) suppressed the secretory proc esses in the pineal gland. An asymmetry of effects was find out while OT unilateral intranasal infusions. We have made an electron-microscopy study of rat pineal gland ultrastructure while the newness stress plus 48-hour water and food deprivation and OT infusions. Under the stress conditions only the "light" pinealocytes showed the increase of protein synthesis and extrusion (an accumulation of dence cored vesicles in the body and in the processes of cells, active chromatin, ..). While the unilateral OT intranasal infusions the stressory changes in "light" pinealocytes decreased. Furthermore, left-side infusions decreased only the extrusion of secretory products, but the right-side infusions suppressed both synthesis and extrusion. A hypothesis was su ggested that OT stimulation of left olfactory bulb increases mainly sympathetic influence on visceral organs and pineal gland, when the right bulb stimulation predominantly results in parasympathetic activity increase.

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Sibarov D.A., Kovalenko R.I., Oxytocin as a regulator of pineal gland cells secretory activity, XXXIII International Congress of Physiological Sciences, SPb, P070.34, 19 97. A.A.Ukhtomski Institute of Physiology, St.Petersburg State , St.Petersburg Stete University, RUSSIA Both hypothalamo-hypophyseal complex and pineal gland plays a great role in adaptive reactions on variable conditions of environment. Pineal peptides and melatonin take part in forming of reactions on osmotic and hypoxic influence. Nerve fibres from epithalamic area, limbic system and hypothalamus are revealed in the pineal gland. Some of them are expected to be of oxytocinergic nature. Formerly we discovered that intraventricular injections of oxytocin (OT) suppressed the secretory proc esses in the pineal gland. An asymmetry of effects was find out while OT unilateral intranasal infusions. We have made an electron-microscopy study of rat pineal gland ultrastructure while the newness stress plus 48-hour water and food deprivation and OT infusions. Under the stress conditions only the "light" pinealocytes showed the increase of protein synthesis and extrusion (an accumulation of dence cored vesicles in the body and in the processes of cells, active chromatin, ..). While the unilateral OT intranasal infusions the stressory changes in "light" pinealocytes decreased. Furthermore, left-side infusions decreased only the extrusion of secretory products, but the right-side infusions suppressed both synthesis and extrusion. A hypothesis was su ggested that OT stimulation of left olfactory bulb increases mainly sympathetic influence on visceral organs and pineal gland, when the right bulb stimulation predominantly results in parasympathetic activity increase.