School Of Basic And Applied Sciences

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Subject: search.filters.subject.Hypothalamus

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    Hormones of hypothalamus and ageing
    (Springer, 2018) Kaur, Gurcharan; Parkash, Jyoti
    Hypothalamus being the master regulator of the vertebrate endocrine system undergoes many adjustments/alterations which body makes during the course of aging. Moreover, the endocrinological basis of aging in male and female organisms is very complex, with multiple hormones along the hypothalamic-pituitary (HP) axis interacting with each other via different feedback loops to maintain homeodynamic state. Also the sensitivity of the hypothalamus to the external stimuli decreases with age mainly due to its lack of sensitivity towards the feedback system The endocrine system is although severely affected by aging but all the organ systems are not affected at the same time or in the same way. During aging cellular protein synthesis machinery as well as immune functions are diminished and gradually physiological functions decline. There is also an increase in fat mass, a loss of muscle mass and strength, and a decrease in bone mineral density profile that contribute to declining health status with increasing age. The hallmarks of aging such as Genomic instability, Telomere attrition, Epigenetic alterations, Loss of proteostasis, Dysregulated Nutrient Sensing, Mitochondrial dysfunction, Altered intracellular communication, Cellular senescence etc. are well reported in literature. In this chapter we have compiled information and discussed various hormonal changes that occur with age in hypothalamus and pituitary gland and how these two master regulators gradually lose their sensitivity with the increasing age.
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    A microRNA switch regulates the rise in hypothalamic GnRH production before puberty
    (Nature Publishing Group, 2016) Messina, Andrea; Langlet, Fanny; Chachlaki, Konstantina; Roa, Juan; Rasika, Sowmyalakshmi; Jouy, Nathalie; Gallet, Sarah; Gaytan, Francisco; Parkash, Jyoti; Tena-Sempere, Manuel; Giacobini, Paolo; Prevot, Vincent; Messina, A.; Langlet, F.; Chachlaki, K.; Roa, J.; Rasika, S.; Jouy, N.; Gallet, S.; Gaytan, F.; Parkash, J.; Tena-Sempere, M.; Giacobini, P.; Prevot, V.
    A sparse population of a few hundred primarily hypothalamic neurons forms the hub of a complex neuroglial network that controls reproduction in mammals by secreting the 'master molecule' gonadotropin-releasing hormone (GnRH). Timely postnatal changes in GnRH expression are essential for puberty and adult fertility. Here we report that a multilayered microRNA-operated switch with built-in feedback governs increased GnRH expression during the infantile-to-juvenile transition and that impairing microRNA synthesis in GnRH neurons leads to hypogonadotropic hypogonadism and infertility in mice. Two essential components of this switch, miR-200 and miR-155, respectively regulate Zeb1, a repressor of Gnrh transcriptional activators and Gnrh itself, and Cebpb, a nitric oxide-mediated repressor of Gnrh that acts both directly and through Zeb1, in GnRH neurons. This alteration in the delicate balance between inductive and repressive signals induces the normal GnRH-fuelled run-up to correct puberty initiation, and interfering with this process disrupts the neuroendocrine control of reproduction. ? 2016 Nature Publishing Group. All rights reserved.