1. Anterior and Posterior hormones

2. OBJective
Classification of Hormones
Mechanism of action of Hormones
Anterior Pituitary Hormones
Posterior Pituitary Hormones

3. § Introduction
The “master gland”— controls three other endocrine glands
Better to think of the pituitary gland as the relay center—
Its function covers both endocrine target glands and nonendocrine target glands

4. Classification of hormones
1. Hypothalamic hormones
Thyrotropin releasing hormone (TRH) – peptide
Corticotropin releasing hormone (CRH) – peptide
Gonadotropin releasing hormone
(GnRH – Gonadorelin): LH-RH/FSH-RH – peptide
Growth hormone releasing hormone: (GHRH) – peptide
Prolactin releasing hormone (PRH): Unknown
Prolactin release inhibitory hormone (PRIH):
Dopamine (DA)
Growth hormone release inhibitory hormone:
(GHRIH): Somatostatin – peptide

5. 2. Pituitary hormones
a) Anterior Pituitary hormones (-tropins/-trophins)
Growth hormone (GH) − Somatotropin
Prolactin
Adrenocorticotropic hormone (ACTH, Corticotropin)
Thyroid stimulating hormones (TSH, Thyrotropin)
Gonadotropins
- Follicle stimulating hormone (FSH)
- Luteinizing hormone (LH)
b) Posterior Pituitary hormones
Oxytocin
Antidiuretic hormone (ADH, Vasopressin)

6. 2. Thyroid hormones
Thyroxine (T4), Triiodothyronine (T3)
Calcitonin
3. Parathyroid hormone: Parathormone (PTH)
4. Hormones of endocrine pancreas: Insulin, Amylin, Glucagon
5. Adrenal hormones
a) Hormones of Adrenal cortex (Steroids)
- Glucocorticoids (GCS): Hydrocortisone, Cortisone
- Mineralocorticoids: Aldosterone
- Sex steroids: Dehydroepiandrosterone (Testost.)
b) Hormone of Adrenal medulla: Adrenaline
6. Hormone of Gonads
a) Androgens: Testosterone
b) Estrogens: Estradiol
c) Progestins: Progesterone

7. Estrogens, Progesterone, Chorionic gonadotropin
8. Placental hormones
Estrogens, Progesterone,
Chorionic gonadotropin
9. Hormone of Adipocytes:
Leptin – acts on receptors in the
hypothalamus of the brain where
it inhibits appetite.
10. Ghrelin is a peptide hormone
that is produced mainly by
the fundus of the stomach and
epsilon cells of the pancreas.
It stimulates hunger. Ghrelin levels increase
before meals and decrease after meals.

8. Mechanisms of hormone action
1. Action on the cell membrane receptors
a) Through alteration of intracellular cAMP concentration
ACTH, Adrenaline, Calcitonin, Glucagon, FSH, LH, PHT,
some hypothalamic RH, TSH, Vasopressin (via V2-rec.)
Alteration of protein kinase A
Regulation of cell function: Ca2+ acting
as a third messenger in some situations

9. Oxytocin and Vasopressin (via V1-rec.)
b) Through the IP3 and DAG generation
Oxytocin and Vasopressin (via V1-rec.)
Release of intracelullar Ca2+
and protein kinase C activation

10. Phosphorylation cascade
c) Direct transmembrane activation
of tyrosine kinase
GH, Insulin, Prolactin
Phosphorylation cascade
Regulation of various enzymes

12. 2. Action on the intracellular (steroid or thyroid) receptors
a) At cytoplasmic receptors:
Steroid hormones, Calcitriol

13. b) Directly at nuclear receptors: Thyroid hormones (T3, T4)
T3 or T4 penetrates the nucleus
Combines with their receptors
Alters DNA-RNA mediated
protein synthesis

14. § Pituitary Gland (Hypophysis)

15. § Pituitary Gland (Hypophysis)
Suspended from hypothalamus by stalk (infundibulum)
Location and size
housed in sella turcica of sphenoid bone
1.3 cm diameter
Adenohypophysis (________ pituitary)
arises from hypophyseal (Rathke’s) pouch (outgrowth of pharynx);
Neurohypophysis (________ pituitary)
arises from brain;
Magnocellular neurons– supraoptic and paraventricular nuclei; Nerve endings?

17. Development of the anterior pituitary

18. § Hypothalamic-hypophyseal portal system--1
Hypothalamic hormones travel in portal system from hypothalamus to anterior pituitary
Primary capillaries (plexus)--?
Secondary capillaries (plexus)--?
Hypothalamic hormones regulate hormones secretion by anterior pituitary
Example— Gonadotropin-releasing hormone (GnRH) regulates FSH & LH secretion

19.    

20.   

21. • ●● Neurosecretory neurons Hypothalamus Hypophysiotropic H.:
Systemic
arterial
inflow 1 2
Anterior pituitary
Hypothalamic-hypophyseal
portal system 3 6
System
venous
outflow 4
Posterior pituitary 5 •
Anterior pituitary hormones:

22. § Hypothalamic-hypophyseal portal system--2
Advantages (of this portal system)—
Almost all the blood supplied to the anterior pituitary must first drain through the __________________________
Releasing/inhibiting hormones then can directly deliver to the anterior pituitary in what fashion ? ____________________________
Therefore, only minute amounts of neural secretions are needed to achieve biologically effective concentrations in pituitary blood.

23. Check Point Questions--
Besides hormones, give another way for intercellular communication.
Give an example of a hormone. Why does your example qualify as a hormone? (hint: definition of hormone)
Give an example of a hypothalamic hormone.
What is the target tissue of a hypothalamic hormone secreted into the hypothalamic- hypophyseal portal system?

24. § Hormones secreted by anterior pituitary
FSH (follicle stimulating hormone)
LH (luteinizing hormone)
The above two are called gonadotropins
TSH (thyroid stimulating hormone, thyrotropin)
ACTH (adrenocorticotropic hormone)
GH (growth hormone; somatotropin or somatotropic hormone)
PRL (prolactin)
Tropic (trophic) hormones-- target other endocrine glands to release their own hormones; which ones above?

25. 3 hormonal families of the anterior lobe:
(ALL proteins) 2. 1. 3.

26. § Glycoprotein hormone family– TSH, FSH, LH
TSH– to stimulate the secretion of thyroid hormone
FSH & LH– important for the function of the testes and the ovaries
FSH– growth of ovarian follicles and formation of sperm
LH (in women)– induce ovulation and the formation of the corpus luteum; stimulate the ovarian production of estrogen and progesterone
LH (in men)– stimulates the production of Testosterone; what cells?

27. § Glycoprotein hormone family (continued)
2 peptide subunits– alpha + beta
The three glycoprotein hormones and hCG (Human chorionic gonadotropin; a placental hormone) all share the same alpha subunit. Fig. 2.3
Both subunits need to be present to be functional.
Beta subunits are encoded in separate genes located on different chromosomes.

28. 4 Glycoproteins– all of them share a common alpha subunit

29. § Growth hormone and prolactin
Growth hormone (GH) is required for proper adult stature.
Species specificity: primates for primate GH
Metabolic effects
Prolactin (PRL) is required for milk production in post-partum women.
In men or nonlactating women-- not clear; however, evidence suggests it may has to do with the immune function.
Human pracental lactogen (HPL) = human chorionic somatomammotropin

30. 2 GH & 3 human placental lactogen genes
3 single-stranded peptides are similar in their structures and functions
2 GH & 3 human placental lactogen genes
(lactogen)

31. § Adrenocorticotropin family
ACTH (adrenal corticotropic hormone) regulates hormone secretion by the cortex of the adrenal glands.
The gene produces ACTH is called POMC (pro- opiomelanocortin) in corticotropes and other cells by prohormone convertases.
(Corticotropes) ACTH is the only one has an established physiological role in humans
(melanocytes and keratinocytes)– pigmentation by MSH
(Melanotrope in arcuate neurons)– food intake

32. Pro-opiomelanocortin (POMC), a gene, products
P. convertases 1. 2. 3.
Melanocyte-stimulating hormone (MSH)
Corticotropin-like intermediate lobe peptide (CLIP)

33. Regulation of Anterior Pituitary hormones

34. § Regulation of anterior pituitary function
Primarily by the CNS– All pituitary hormones except PRL would decline in the absence of the hypothalamus
Experiment--Pituitary gland is removed and in vitro . . .
By hormones produced in peripheral target glands—
Example– inhibin secreted from gonads
All anterior pituitary hormones secreted in a diurnal pattern.

35. § Feedback regulation of anterior pituitary hormone secretion

40. http://www. elp. manchester. ac. uk/pub_projects/2000/mnby6kas/ACTH

42. Hormones of Posterior Pituitary

43. Objectives Of Posterior Pituitary Homrones
Posterior Pituitary Hormones
ADH
Water regulation
Oxytocin
Milk secretion
Parturition
Disorders
Summary

44. The neurohypophysis develops from the differentiation of neural ectoderm into the pars nervosa, the infundibular stem, and the median eminence. The infundibular stem is surrounded by the pars tuberalis.

50. Regulation of anterior pituitary function

62. FIGURE 2.10

71. Disorders of Anterior & Posterior Pituitary

72. Pituitary adenoma
Lacotrophic – secrete
prolactin (galactorrhea,
infertility, impotence)
Somatotrophic – secrete GH
(acromegaly)
Corticotrophic – secrete
ACTH (Cushing’s disease)
Gonadotrophic – secrete
LH & FSH (no symptoms)
Thyrotrophic – secrete TSH
(occasionaly hyperthyroidism)
Transsphenoidal resection
of pituitary tumour mass
via the endonasal approach

77. Summary of Posterior Pituitary hormones

79. PRACTICE QUESTIONS

80. Q1. Which of the following hormones act through the IP3 and DAG generation mechanism?LH
Oxytocin
TSH

81. Key: C: Oxytocin
GH, Insulin, Prolactin act directly through transmembrane activation of tyrosine kinase activity
FSH, LH, TSH act through alteration of intracellular cAMP concentration
Oxytocin and Vasopressin (via V1-rec.) release of intracelullar Ca2+ and protein kinase C activation
TSH through alteration of intracellular cAMP

82. Q2: Which of the following hormones stimulate the contraction of uterine myometrium and breast tissue in females?
ADH
Growth hormone
Oxytocin
Prolactin

83. Key: C: Oxytocin
ADH is also called arginine vasopressin. It's a hormone made by the hypothalamus in the brain and stored in the posterior pituitary gland
Growth hormone (GH), also called somatotropin or human growth hormone, peptide hormone secreted by the anterior lobe of the pituitary gland. 
The two main actions of oxytocin in the body are contraction of the womb (uterus) during childbirth and lactation.
Prolactin is mainly used to help women produce milk after childbirth. It's important for both male and female reproductive health

84. Q3: The supraoptic nucleus of the hypothalamus is believed to control secretion of which of the following hormones?
Antidiuretic hormone (arginine vasopressin)
Adrenocorticotropic hormone
Growth hormone
TSH

85. Key: A
It is thought that the secretion of antidiuretic hormone (ADH)-also called arginine vasopressin (AVP)-and oxytocin by the neurohypophysis is regulated in the hypothalamic supraoptic and paraventricular nuclei, respectively.
ACTH is controlled by POMC from hypothalamus
Growth hormone is controlled by GHRH from the hypothalamus
TSH is controlled by TRH from the hypothalamus

86. 4. Which of the following hormones stimulate the synthesis of milk protein?
Luteinizing hormone
Prolactin
Thyroid stimulating hormone
Growth hormone
Key: d: Prolactin
Prolactin (PRL), also known as luteotropic hormone or luteotropin, is a protein that is best known for its role in enabling mammals, usually females, to produce milk.
Key: d: Prolactin

87. Key: d: Prolactin
LH triggers ovulation and development of the corpus luteum. In males, LH stimulates Leydig cell production of testosterone.
Prolactin (PRL), is a protein that is best known for its role in enabling mammals, usually females, to produce milk.
TSH is a pituitary hormone that stimulates the thyroid gland to produce thyroxine (T4), and then triiodothyronine (T3)
Growth hormone is a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals

88. 5. The release of which one of the following hormones is inhibited by thyroxine?
ACTH GH LH
TSH
Key: c: TSH
Key: c: TSH

89. Key: c : TSH
ACTH is secreted from the anterior pituitary in response to corticotropin-releasing hormone from the hypothalamus
Growth hormone (GH): GH is essential in early years to maintaining a healthy body composition and for growth in children. IGF-1 is regulated Growth hormone in human body
Luteinizing hormone (LH): LH works with FSH to ensure normal functioning of the ovaries and testes
TSH in turn is under feedback control by the thyroid hormones T4 and T3.