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The molecular mechanisms and role of purinergic signaling in hypothalamus
Ivetic, Milorad ; Zemková, Hana (advisor) ; Mysliveček, Jaromír (referee) ; Smejkalová, Terézia (referee)
(EN): Extracellular ATP and purinergic P2 receptors (P2X and P2Y) are involved in a signaling network called "purinergic signaling" which is widely exploited in both somatic and neuronal tissues, and is also operative in endocrine system. The main focus of my thesis is on the role and expression of P2X and P2Y receptors in hypothalamic supraoptic nuclei (SON) producing hormones vasopressin and oxytocin, and the suprachiasmatic nuclei (SCN), the principal circadian pacemaker in mammals. In the first part of my thesis, we tested the hypothesis that P2X and P2Y receptors play a role in the enhanced release of hormones from magnocellular SON neurons stimulated through fasting/refeeding experimental protocol. We studied the effect of 2 h of refeeding after 48 h of fasting on hormone, P2X and P2Y mRNA expression in the SON tissue of 30-day-old rats, and the effect of ATP on electrophysiological properties of SON neurons in brain slices from control and fasted/refed rats. Quantitative real-time PCR revealed that the expression of P2X2 and arginine-vasopressin (AVP) mRNA was increased and P2Y1 mRNA expression was decreased in fasted/refed rats compared to controls, whereas P2X4, P2X7, P2Y2 and oxytocin mRNA levels were not significantly changed. Whole-cell patch clamp recordings showed that the amplitude...
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Ca2+ signalling in magnocellular neurones of the rat supraoptic nucleus.
Kortus, Štěpán ; Zápotocký, Martin (advisor) ; Šuta, Daniel (referee) ; Hromádka, Tomáš (referee)
The magnocellular neurosecretory cells (MNCs) of the hypothalamus project axons from the supraoptic nucleus to the posterior pituitary gland, where they secrete either oxytocin or vasopressin into the circulation. Oxytocin is important for delivery at birth and is essential for milk ejection during suckling. Vasopressin primarily promotes water reabsorption in the kidney to maintain body fluid balance. The profile of oxytocin and vasopressin secretion is principally determined by the pattern of action potentials initiated at the cell bodies in the hypothalamus. MNCs principally secrete hormones from terminals in the pituitary, but the secretion also occurs from their dendrites in the supraoptic nucleus, where they diffuse and affect the neighbouring cells. Mechanisms controlling the oxytocin and vasopressin secretion from MNCs have been extensively studied over the last decades and it is assumed that the relationship between Ca2+ signalling, secretion from dendrites, and the firing patterns is essential in understanding the magnocellular neurosecretory system. In this project, we combine mathematical analysis and experimental measurements of Ca2+ activity of MNCs of transgenic rats expressing an arginine vasopressin-enhanced green fluorescent protein (AVP-eGFP) or oxytocin-monomeric red fluorescent...
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Ca2+ signalling in magnocellular neurones of the rat supraoptic nucleus.
Kortus, Štěpán ; Zápotocký, Martin (advisor) ; Šuta, Daniel (referee) ; Hromádka, Tomáš (referee)
The magnocellular neurosecretory cells (MNCs) of the hypothalamus project axons from the supraoptic nucleus to the posterior pituitary gland, where they secrete either oxytocin or vasopressin into the circulation. Oxytocin is important for delivery at birth and is essential for milk ejection during suckling. Vasopressin primarily promotes water reabsorption in the kidney to maintain body fluid balance. The profile of oxytocin and vasopressin secretion is principally determined by the pattern of action potentials initiated at the cell bodies in the hypothalamus. MNCs principally secrete hormones from terminals in the pituitary, but the secretion also occurs from their dendrites in the supraoptic nucleus, where they diffuse and affect the neighbouring cells. Mechanisms controlling the oxytocin and vasopressin secretion from MNCs have been extensively studied over the last decades and it is assumed that the relationship between Ca2+ signalling, secretion from dendrites, and the firing patterns is essential in understanding the magnocellular neurosecretory system. In this project, we combine mathematical analysis and experimental measurements of Ca2+ activity of MNCs of transgenic rats expressing an arginine vasopressin-enhanced green fluorescent protein (AVP-eGFP) or oxytocin-monomeric red fluorescent...
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