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1. ENDOCRINE PHARMACOLOGY
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2. HYPOTHALAMUS AND
PITUITARY HORMONES
Dr Sindwa Kanyimba
Lecturer, Pharmacology

3. The main function of the hypothalamus is to link the nervous
system to the endocrine system via the pituitary gland. The
hypothalamus produces releasing and inhibiting hormones,
which regulate the production of pituitary hormones.
Pituitary gland hormones are involved in regulation of growth,
blood pressure, metabolism, sexual function, thyroid gland
function, some aspects of pregnancy, childbirth, breastfeeding,
water and electrolyte balance and temperature.
Pituitary gland hormones either control the secretion of other
glands or directly act on the target tissues.
INTRODUCTION

4. LEARNING OBJECTIVES
1.
2.
Describe the physiological actions of hypothalamus and
pituitary hormones
Describe the clinical applications of hypothalamus and
pituitary hormones, hormone agonists and hormone
antagonists

5. HYPOTHALAMUS HORMONES
1.
2.
3.
4.
5.
6.
7.
8.
Growth hormone releasing hormone (GHRH)
Growth hormone release-inhibiting hormone (somatostatin)
Thyrotrophin releasing hormone (TRH)
Corticotrophin releasing factor (CRF)
Gonadotrophin-releasing hormone (GnRH, LHRH)
Melanocyte stimulating hormone releasing factor
Prolactin releasing factor (PRF)
Prolactin release inhibiting factor (dopamine)
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6. HYPOTHALAMUS HORMONES
•
•
Growth hormone releasing hormone (GHRH)
Stimulates anterior pituitary to secrete growth hormone
Somatostatin (growth hormone release-inhibiting hormone)
Produced in the hypothalamus, parts of the CNS, pancreas
and GIT
Inhibits the secretion of growth hormone, thyroid
stimulating hormone (TSH), prolactin, insulin, glucagon and
GIT secretions
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7. HYPOTHALAMUS HORMONES …. CONT’D
Thyrotropin releasing hormone (TRH)
Stimulates the release of TSH (thyrotropin) from the anterior
pituitary
Corticotrophin releasing factor (CRF)
Stimulates release of corticotrophin (adrenocorticotrophic
hormone, ACTH) from the anterior pituitary
Melanocyte stimulating hormone releasing factor
Stimulates the release of melanocyte stimulating hormone
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8. HYPOTHALAMUS HORMONES …. CONT’D
•
•
Gonadotrophin-releasing hormone (GnRH, LHRH)
Regulates the secretion of the gonadotrophins (FSH and LH)
Pulsatile administration stimulates gonadotrophin secretion
Continuous administration inhibits gonadotrophin secretion
Prolactin releasing factor (PRF)
Stimulates prolactin release: regulates breast development
and lactation
Prolactin release inhibiting factor (dopamine)
Inhibits prolactin release
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9. USES OF HYPOTHALAMUS HORMONES
Hypothalamic hormone Uses
Sermorelin (GHRH analog) Diagnosis of GH deficiency
Octreotide (somatostatin
analog)
Acromegaly, hormone secreting tumours,
bleeding oesophageal varices
TRH Diagnosis of thyroid disorders
CRF Diagnostic tests in Cushing’s disease, tests
of hypothalamic and pituitary function
Gonadorelin (GnRH) Diagnostic tests of hypogonadism, infertility
Leuprolide (GnRH analog) Prostatic cancer, uterine fibroids,
endometriosis, breast cancer, precocious
puberty
Triptorelin (GnRH analog) Infertility, endometriosis, prostate cancer,
hirsutism 9

10. OTHER DRUGS THAT AFFECT HYPOTHALAMUS
HORMONES
•
•
GnRH antagonists
Examples
Ganirelix, abarelix and cetrorelix (competitive antagonists of
GnRH receptors thus inhibit secretion of gonadotrophins from
the pituitary)
Uses
Infertility (ganirelix and cetrorelix are used during in-vitro
fertilization to suppress the LH surge and ovulation until the
follicles are mature)
Prostate cancer (abarelix is used to inhibit LH secretion
thus reduces testosterone synthesis)
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11. OTHER DRUGS THAT AFFECT HYPOTHALAMUS
HORMONES …. CONT’D
•
•
•
Dopamine receptor agonists
Examples: bromocriptine, cabergoline
Inhibit prolactin release
Uses: (1) To suppress lactation and breast engorgement
after delivery (e.g. after delivery of a still-born) and following
abortion (2) Inhibit prolactin secretion in conditions
associated with excess prolactin secretion (e.g. prolactin
secreting tumours, amenorrhoea, galactorrhoea)
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12. PITUITARY HORMONES
1.
2.
3.
4.
5.
6.
1.
2.
Anterior pituitary hormones
Growth hormone (GH)
Adrenocorticotrophic hormone (corticotrophin, ACTH)
Thyroid-stimulating hormone (thyrotrophin, TSH)
Gonadotrophins (follicle stimulating hormone [FSH] and
luteinizing hormone [LH])
Melanocyte stimulating hormone (MSH)
Prolactin
Posterior pituitary hormones
Vasopression
Oxytocin
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13. GROWTH HORMONE (GH, SOMATROPIN)
•
•
•
•
Stimulates the growth of all organs except brain and
eye
Increases the uptake of amino acids by tissues, protein
synthesis and positive nitrogen balance
Causes lipolysis and reduced glucose uptake by
skeletal muscles
Brings about linear growth
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14. GROWTH HORMONE …. CONT’D
•
•
•
These anabolic actions are mediated by somatomedins
(insulin-like growth factors) produced in the liver
The secretion of growth hormone is regulated by GHRH and
somatostatin
Growth hormone deficiency in children results in dwarfism
while excess production results in gigantism in children, and
acromegaly in adults
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15. GONADOTROPHINS
•
•
The gonadotrophins are follicle stimulating hormone (FSH)
and luteinising hormone (LH)
Gonadotrophins regulate gonadal function
In females
LH increases oestrogen production in the ovary and is
required for progesterone production by the corpus luteum
after ovulation
FSH stimulates follicular development and maturation
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16. GONADOTROPHINS …. CONT’D
•
•
In males
LH induces testosterone production by the interstitial cells
of the testes (thus also referred to as interstitial cell
stimulating hormone)
FSH stimulates spermatogenesis and the synthesis of
androgen binding protein
For therapeutic purposes, human menopausal gonadotropins
(menotropins), human chorionic gonadotropin (hCG) and FSH
(produced by DNA recombinant technology) are used
Menotropins contain a mixture of LH and FSH, while hCG is
nearly identical in activity to LH
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17. ANTERIOR PITUITARY HORMONES …. CONT’D
•
•
Corticotrophin (adrenocorticotrophic hormone, ACTH)
Controls the synthesis and release of glucocorticoids,
mineralo-corticoids and androgens from the adrenal cortex
Thyroid stimulating hormone (thyrotrophin, TSH)
Stimulates the production and secretion of thyroid hormones
and thus regulates thyroid function
Melanocyte stimulating hormone (MSH)
Promotes melanin synthesis causing darkening of skin
Regulates feeding
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18. ANTERIOR PITUITARY HORMONES …. CONT’D
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•
•
Prolactin
Promotes the growth and development of breast during
pregnancy
Stimulates milk production
Deficiency results in lactation failure and excess prolactin
results in galactorrhea, amenorrhoea and infertility
(prolactin inhibits release of the gonadotrophins)
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19. USES OF ANTERIOR PITUITARY HORMONES AND
HORMONE ANTAGONISTS
Hormone Uses
GH GH deficiency, stimulation of growth in
Turner’s syndrome, chronic renal failure,
burns, cachexia, AIDS wasting, diagnosis
of GH deficiency
Pegvisomant (GH
antagonist)
Acromegaly
ACTH Diagnosis of adrenocortical insufficiency
TSH Diagnosis of thyroid deficiency
Menotropins, FSH
and hCG
FSH-LH deficiency, undescended testes,
amenorrhoea, infertility
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20. ANTI-DIURETIC HORMONE (ADH, VASOPRESSIN)
•
•
•
Synthesized in the hypothalamus
Stored and released from the posterior pituitary
Actions are mediated by three types of specific receptors: (1)
V1A - located in vascular smooth muscle, GIT smooth
muscle, myometrium and kidney (2) VIB - located in CNS and
adrenal medulla (3) V2 - located in renal tubules
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21. ADH: ACTIONS
•
•
•
•
Kidney: enhances reabsorption of water (due to increased
water permeability in the renal tubule through formation of
water channels [aquaporins] in the renal tubule). This action
is through V2 receptors.
Vasoconstriction with increased blood pressure at high
doses – via V1A receptors
Stimulates the hepatic synthesis and release of coagulation
factor VIII and von Willebrand factor - via V1A receptors
Increased peristalsis and myometrial contraction - via V1A
receptors
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22. ADH
•
•
•
Clinical Uses
Diabetes insipidus of pituitary origin (desmopressin a longer acting
analogue of vasopressin is used)
Bleeding esophageal varices (vasopressin constricts mesenteric
blood vessels). Vasopressin analogues are used: desmopressin,
terlipressin and lypressin (the analogues are more selective for
mesenteric vasculature).
Haemophilia and von Willebrand’s disease (desmopressin)
Adverse Effects
Myocardial ischaemia, fluid retention, headache, nausea, abdominal
cramps
Contraindications
Cardiovascular disease
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23. OXYTOCIN
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•
•
•
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Oxytocin is synthesized in the hypothalamus and secreted by the
posterior pituitary
Actions
Elicits milk ejection from the breast
Stimulates contractions of uterine smooth muscle (directly and
through inducing synthesis of prostaglandins)
Oxytocin has been associated with parental, mating and social
behavior
Clinical Uses
Induction and maintenance of labour
To control post-partum haemorrhage
To stimulate milk ejection from the breast
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24. OXYTOCIN …. CONT’D
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•
•
•
Adverse effects
Hypertension and fluid overload (ADH activity)
Uterine rupture
Contra-indications
Should not be used after uterine surgery or if signs of fetal
distress are present
Cardiovascular disease
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25. END
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