Mechanism of melatonin stimulation of growth hormone release via somatostatin inhibition
Joseph Angelo Israel Peguit
University of the Philippines in the Visayas Cebu College
Natural Sciences and Mathematics Division
Secretion of growth hormone is affected by two primary hormones: Growth hormone-releasing hormone and somatostatin. The former is the primary stimulant to promote growth hormone secretion while the latter is the primary inhibitor that prevents growth hormone secretion. Many studies have already shown that melatonin stimulates secretion of growth hormone via somatostatin inhibition but its mechanisms remain unknown. I hypothesized that melatonin inhibits somatostatin at transcription level through inhibition of important somatostatin transcription factors. I collected data from primary and secondary literature to acquire information on the target tissues, receptors and cellular mechanisms of melatonin. I collected information about somatostatin with emphasis on the mechanisms of its expression. Results showed that melatonin inhibits transcription of somatostatin through inhibition of Cyclic-adenosine monophosphate response element binding protein (CREB) which is a constituent of the transcription factors for somatostatin expression.
Melatonin is a major secretion of the pineal hormone primarily involved in animal sleeping patterns. For such function, people have been taking melatonin pills over the counter to cure sleeping disorders. Approval from FDA on these melatonin pills is not yet available since the total function of this hormone has not been fully known. However, intensive researches have been going on trying to elucidate the entire function of this hormone. Full understanding on the physiology of this hormone may precede medical innovations as it can help us understand more of our development. One of the recent discoveries on this hormone is its ability to act as an antioxidant at the same time attenuating the activity of antioxidative enzymes in the body. In connection to its major role of promoting sleep, its medical benefits provide insights to the physiological process happening at the body while at sleep.
It has been established that Growth hormone is produced by the anterior lobe of the pituitary gland. It is primarily stimulated by Growth hormone-releasing hormone and primarily inhibited by somatostatin. Secretion of the growth hormone promotes uptake of amino acids, metabolism of fats and bone formation.
I collected results from various primary and secondary literatures available online. I selected and analysed a total of thirty-three primary and secondary literatures.In my analysis, I considered the specific tissues that were studied since results do differ even if methodologies are the same.
I collated the results obtained through establishing connections to form a cohesive explanation on the mechanism of melatonin to inhibit somatostatin. Nonetheless, all my results are hypothetical as for the moment until physical experimentation must be done.
It is widely accepted that melatonin (MT) is a neurohormone that is the key regulator of biological rhythms. Intensive study on MT after its discovery demonstrated that it is involved also in, genital development, pigment metabolism, immune response, neutralization of free radicals[2,3], cell growth and proliferation. The chemical structure of melatonin renders it both lipophilic and partially hydrophilic[7,10]. Such property is very crucial since its transport to different parts of the body does not need specialized mechanisms. MT synthesis primarily occurs in the pineal gland and it has been established that cells from the gastrointestinal tract, retina, ciliary body, lens, Harderian gland, brain, thymus, airway epithelium, bone marrow, gut, ovary, testicle, placenta, lymphocytes and skin altogether...
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