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Pharmacology of drugs used in treatment of pituitary and thyroid disorders, so let’s get right into it. joined at the base of the brain, the key players in the endocrine system. “the master gland” due to its function to control the secretion or inhibition of hormones. hormones are the most potent chemical
Messengers in our bodies, telling the body what to do and when. that’s why imbalanced or poorly functioning hormones can cause a variety of medical problems. now, the “master” pituitary gland consists of an anterior lobe, which contains specialized cells that produce and secrete hormones in response to
Hormones released from the hypothalamus, neuronal projections extending from the so as you can see, hypothalamic hormones can be broadly classified into two groups. that act on the anterior pituitary gland such as thyrotropin-releasing hormone (trh) that stimulates specialized endocrine cells called
Thyrotrophs (t) to release thyroid stimulating hormone (tsh), which in turn stimulates thyroid gland to produce and release thyroid hormones; the next one is gonadotropin-releasing hormone (gnrh) that stimulates gonadotrophs (g) to release follicle-stimulating hormone (fsh) and luteinizing hormone (lh), which in turn
Stimulate the reproductive functioning of the ovaries and testes; the next one is corticotropin-releasing hormone (crh) that stimulates corticotrophs (c) to release adrenocorticotropic hormone (acth), which produce and secrete certain steroid hormones; the next one is growth hormone-releasing hormone (ghrh)
That stimulates somatotrophs (s) to release growth hormone (gh), which in turn stimulates the liver and other tissues to produce growth stimulants called insulin-like growth factors; and lastly we have two inhibiting hormones that is growth hormone-inhibiting hormone (ghih), which inhibits somatotrophic cell release
Of growth hormone, and prolactin-inhibiting hormone (pih), which is simply the neurotransmitter now, moving on to the second group transported down the axons of the same neurons that synthesize them to the posterior pituitary from where they’re released into the circulation. which acts primarily on the kidney
To regulate water balance in the body; and oxytocin, which all right, so as you can see, hormones produced a crucial role in regulating metabolism, of that, many drugs have been developed order to treat various endocrine disorders. so, now let’s take a closer look at how these drugs work to produce
Their therapeutic effects, to gain better understanding of the mechanism the mechanism by which thyroid hormones are is the functional unit of thyroid gland. intrafollicular colloid and follicular cells, production of thyroid hormones. the recipe for making thyroid hormones calls for two principle
Called thyroglobulin, which is synthesized in the rough endoplasmic reticulum of follicular cell, and then is secreted into the colloid; the second ingredient is an iodide, which is actively pumped into the cell by sodium-iodide symporter, and then is passively transported into the colloid along with thyroglobulin. in
The colloid, with the help of an enzyme called thyroid peroxidase, iodide (i-) is oxidized to iodine (i0) and hormone synthesis begins with the addition of iodine molecules in a process called iodination. and the entire complex re-enters the follicular cell. back inside the cell, proteolytic enzymes thyroid
Molecules, thyroxine known as t4 where they quickly bind to carrier now, free extracellular t4 and t3 enter the target cell through transporter proteins. once has greater biological activity than t4, 2 abbreviated d1 and d2 that catalyze the intracellular levels of the active hormone. as d3) serves to
Inactivate t4 by converting therefore limiting the amount of t4 that can be used to form t3. in the final step, t3 moves to the nucleus and binds to the thyroid hormone with the retinoid x receptor (rxr) to induce transcription of target genes known as thyroid response elements. this leads to synthesis of
Now, the drugs used in treatment of thyroid disorders can be generally divided into two treat the condition in which there is inadequate hypothyroidism. medications used to treat is a synthetic version of t4, liothyronine, which is a synthetic combination of t4 and t3, natural thyroid hormone prepared from
Dried now, moving on to the second group that includes there is overproduction of thyroid hormones, known as hyperthyroidism. medications used to treat hyperthyroidism include propylthiouracil thyroid peroxidase that is required for coupling of iodotyrosines in thyroglobulin propylthiouracil also
Inhibits deiodinase 1 all right, now that we discussed drugs move on to our next pharmacological target that is gonadotropin-releasing hormone receptor (gnrhr). so, the hypothalamic hormone, gnrh, is released and transported to the anterior pituitary receptors expressed by the pituitary gonadotrophs. under various
Physiological conditions, and fsh. in order to modulate the gnrh effects for therapeutic purposes, a number of gnrh analogs or upregulate the secretion of lh and fsh. are more potent and have longer half-life than natural gnrh. they produce an initial results in increased secretion of lh and fsh, followed
By downregulation and inhibition of the pituitary-gonadal axis. in comparison to gnrh agonists, gnrh antagonists such as degarelix, elagolix, ganirelix and cetrorelix promptly suppress pituitary gonadotropin by competitively blocking gnrh-receptor, thereby avoiding the initial stimulatory phase of the agonists. the
Resulting suppression of lh and fsh in turn leads to profound inhibition of estrogen and androgen synthesis, which makes these agents effective on the other hand, the deficiency of both lh and fsh as a result of hypothalamic or pituitary disease can cause infertility or subfertility both in men and women. to address
This problem, variety of pharmaceutical preparations of lh and fsh have been developed to stimulate spermatogenesis in men and to induce follicle development and ovulation in women. these preparations include menotropins, which consist of a purified mixture of lh and fsh; urofollitropin, which is a purified form of
Human fsh; follitropin, which is a form of recombinant human fsh; lutropin, which is a recombinant form of human lh; and choriogonadotropin alfa, which is a recombinant form of human chorionic produced by the placenta during pregnancy that shares structural similarities with lh and thus binds to and activates
The same receptor. all right, moving on to our next pharmacological so, the main action of adrenocorticotropic hormone (acth) on the adrenal cortex is to stimulate the androgen hormones. specifically, inside the cells of the adrenal cortex, stimulation by acth activates cholesterol side-chain cleavage enzyme, the
Precursor of all adrenocortical hormones including mineralocorticoids, glucocorticoids, diseases affecting adrenal gland can be divided into disorders of hormone deficiency and disorders of hormone excess. addison’s disease is the classic example of adrenocortical insufficiency characterized by inadequate secretion of
Cortisol, for adrenocortical insufficiency involves replacing the missing hormone aldosterone with the synthetic analog such as fludrocortisone, synthetic analogs such as hydrocortisone or prednisone. on the other hand, cushing’s syndrome is the example of excessive cortisol production. involves either
Stopping corticosteroid adrenal tumor is identified, medications such as ketoconazole, mitotane and metyrapone can be used to inhibit enzymes involved in cortisol synthesis. also called somatotropin. so, growth is a very complex process that requires coordinated action of several hormones. growth hormone, although
It has largely indirect effect on growth, the growth process. the pituitary secretes growth hormone in response to the hypothalamus releasing growth-hormone releasing hormone and the stomach releasing ghrelin. the major role of the growth hormone in stimulating body growth is secrete insulin-like growth factor-1
(Igf-1). cartilage cells, resulting in bone growth, as well as formation of new proteins particularly in skeletal muscle cells, resulting in muscle growth. directly bind to its receptors on target cells such as fat cells, causing them to break down triglycerides and suppresses their ability now,
Deficiency in growth hormone can lead to developmental disorders such as growth retardation or dwarfism. to treat these disorders, a synthetic somatotropin can be injected into the body to compensate for insufficient levels of growth hormone. in addition to that, pediatric patients with growth failure and severe igf-1
Deficiency somatotropin, can be treated with a recombinant human igf-1 product called mecasermin. now, the body’s primary mechanism of regulating growth hormone is to release growth hormone-inhibiting hormone also known as somatostatin. somatostatin secreted from the hypothalamus simply inhibits the pituitary
Gland’s secretion of growth hormone. secretion, which can lead to gigantism in forms of somatostatin can be used to reduce such agents are octreotide and lanreotide, which work by binding to somatostatin receptors located on the surface of different cell types now let’s move on to discussing drugs that
Affect prolactin secretion. so, the secretion of prolactin is regulated by dopamine, which is secreted by hypothalamic dopaminergic neurons into the anterior pituitary via portal vessel. dopamine that is released by these neurons causing inhibition of prolactin secretion. include either insufficient prolactin
Levels, excessive prolactin levels, which results in galactorrhea and infertility. two types of drugs can be used to treat these disorders. antagonist such as metoclopramide, which works by blocking d2 receptors from being stimulated, thereby increasing prolactin secretion. the second type includes
Dopamine receptor agonists such as bromocriptine and cabergoline, which stimulate d2 all right, finally before we end, let’s briefly discuss pharmacology of the posterior pituitary hormones that is anti-diuretic hormone also known to the first hormone, when there’s a change in plasma osmolality, volume, or
Redistribution of blood, osmoreceptors located within hypothalamus atria, and caro-tids stimulate the release of vasopressin into the circulation. vasopressin action is mediated primarily by binding to the v2 receptors (v2r) on cells in the distal tubules and collecting ducts of the kidney, which in turn
Stimulates insertion of water-permeable channels called aquaporins into the luminal membrane. osmotic gradient and the urine to become more concentrated. in addition to that, vasopressin can act directly on blood vessels by binding smooth muscle to cause vasoconstriction. now, in terms of therapeutic options,
We have natural vasopressin available in injection form as well as synthetically modified selective v2 receptor agonist called desmopressin (ddavp) that is also available in oral and nasal formulations. vasopressin and desmopressin are treatments of choice for diabetes insipidus, certain bleeding disorders and
Nocturnal involuntary urination. associated with increased vasopressin levels which work mainly by blocking v2 receptors thereby effectively correcting hyponatremia now, moving onto our last hormone that is oxytocin. so, oxytocin has been best known for its roles in female reproduction. for instance, in the
Late stage of pregnancy, stretching of tissues in the uterus and cervix causes local stretch receptors to send nerve impulses to the hypothalamus, which in turn causes the pituitary to secrete oxytocin into the circulation. oxytocin then travels to the uterus and causes the muscles in uterine walls to contract,
Thereby bringing the baby downwards, stretching the cervix even more, and repeating the cycle until birth occurs. after the birth, oxytocin release is stimulated by the suckling of an infant at the breast, which again, triggers the synthesis and release of the oxytocin into the circulation. this time, oxytocin travels
To the breast where it stimulates receptors in the cells of the that results in forcing milk down the duct. oxytocin can be administered to induce labor and with that i wanted to thank you for watching, and as always stay tuned for more.
Transcribed from video
Pharmacology – DRUGS FOR PITUITARY AND THYROID DISORDERS (MADE EASY) By Speed Pharmacology
