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Animal Science 434 Reproductive Physiology. Lecture 6 and 7: Endocrinology. What is the function of the endocrine system?. Integration of Body Functions. nervous and endocrine systems are similar nervous system seconds endocrine system minutes and hours. Neuro-endocrine Response. - PowerPoint PPT Presentation
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Integration of Body Functions
• nervous and endocrine systems are similar
• nervous system» seconds
• endocrine system» minutes and hours
Manipulation of the Endocrine System
• Hormones can be used to regulate body functions»growth (anabolic steroids)
» lactation (GH or STH)
»birth control (Estradiol, Progesterone)
»estrous cycle (PGF2)
»superovulation and embryo transplant (FSH,eCG)
»parturition (oxytocin)
Endocrine Gland
• A ductless gland• Secretes substances (hormones) into
blood or lymph that affect cells elsewhere in the body
• The secretion does not involve loss of tissue
Hormone
• Substance produced by endocrine gland
• Acts on cells, tissues or organs at a place other than where produced
• Acts as a catalyst.
Testes(in bull)
Placenta
Uterus
OvaryAdrenalPineal
Hypothalamus
Pituitary
Pancreas
Thyroid
Endocrine Glands
Classification and Properties of Hormone
A. Site of Production
B. Type of action
1. Primary hormone of reproduction
2. Metabolic hormone
C. Chemical Structure
1. General structure– Proteins and polypeptides
– Steroids
– Fatty acids
– Modified amino acid
2. Size
Classification and Properties of Hormone
A. Site of Production
B. Type of action
1. Primary hormone of reproduction
2. Metabolic hormone
C. Chemical Structure
1. General structure– Proteins and polypeptides
– Steroids
– Fatty acids
– Modified amino acid
2. Size
Function of Hypothalamus• appetite
• thirst
• body temperature
• vasomotor activity
• emotion
• use of body nutrient reserves
• activity of intestine
• sleep
• sexual behavior
• Production and release of releasing hormones
Releasing Hormones of the Hypothalamus
A. Structure
• short chain polypeptides (3 - 44 amino acids)
B. General Function• to cause the release of trophic hormones from
the anterior pituitary gland
Releasing Hormones of the Hypothalamus
C.Hormones
•Gonadotropin releasing hormone (GnRH)
»LH, FSH release
•Thyrotrophin releasing hormone (TRH)
»TSH and prolactin release
•Corticotrophin releasing hormone (CRH)
»ACTH release
•Growth hormone releasing hormone (GH-RH)
•Somatostatin (growth hormone inhibiting hormone)
Cells of the Anterior Pituitary
• LH• FSH• Prolactin• STH• TSH• ACTH
HypothalamusHypothalamus
Nerve CellsNerve Cells
Superior hypophyseal
artery
Hypophyseal portal vessels
Capillary plexus
Posterior pituitary
Capillary plexus
Preoptic nuclei
cell
Preoptic nuclei
cell
Anterior Pituitary Hormones
A.Structure1. glycoproteins or proteins
B.Hormones1. gonadotropins
» Follicle stimulating hormone (FSH)
» Luteinizing hormone (LH)
» Prolactin
Anterior Pituitary Hormones
2.Other trophic hormones•Adrenal Corticotropin (ACTH)
• thyroid stimulating hormone (TSH)
•growth hormone (GH or STH)
Structure of LH, FSH and TSH
• Made of 2 amino acid chains
• chains are the same
• chains differ and give specificity
S S
HypothalamusHypothalamus
Nerve CellsNerve Cells
Posterior pituitary• Oxytocin• ADH
Paraventricular nuclei cell
Paraventricular nuclei cell
Supraoptic nuclei cellSupraoptic nuclei cell
Anterior Pituitary
Capillary plexus
Hypothalamus
Nuclei that produce posterior pituitary
hormones
Nuclei that produce posterior pituitary
hormones
Posterior Pituitary HormonesA.Structure
• polypeptides (9 amino acids)
B. Hormone
• Oxytocin - contraction of smooth muscle
Placental Hormones
• Equine Chorionic Gonadotropin (eCG)» Formation of accessory CL and maintains
pregnancy
• Human Chorionic Gonadotropin (HCG)» Maintains primate CL and pregnancy
• Placental Lactogen (PL)» Development of the mammary gland in
the mother
• Steroids - Estrogen and Progesterone
Gonadal Polypeptide Hormones
• Relaxin» Secreted by CL during pregnancy.
» Parturition
• Inhibin» Inhibits FSH release
Gonadal Steroids
A. General» Origin - ovary, testis, adrenal
» Structure
2
3
4
5
10
1
6
7
8
9 14
13
12
11
15
16
17
19
18
20
DC
BA
SteroidSynthesis
HO
OH
O
OH
HO
CH3
C O
O
CH3
C O
HO
Cholesterol Pregnenolone
Estradiol
ProgesteroneTestosterone
27-C27-C
21-C21-C
19-C19-C
18-C18-C
21-C21-C
Gonadal Steroids Cont.A.General Cont.
» Solubility– Bound to a binding protein for transport
B.Type of Steroids» Androgens - Testosterone
» Estrogen - Estradiol
» Progestin - Progesterone
SteroidSynthesis
HO
OH
O
OH
HO
CH3
C O
O
CH3
C O
HO
Cholesterol Pregnenolone
Estradiol
ProgesteroneTestosterone
MitochondriaMitochondria
Smooth ERSmooth ER
Lipid Hormones - ProstaglandinsFatty AcidsProstaglandins
1. Produced by all tissues of body2. Can have a local effect on tissues (same tissue which produced it)3. Rapidly degraded in lungs
Phospholipids- Rate limiting (Phospholipase A2)
- Precursor to Prostaglandins
Aspirin inhibits
Arachidonic Acid
Cyclo-oxygenase
PGE2PGF2
•Vasodilation•Maintain CL•Ovulation•Implantation
•Vasoconstriction•CL regression•Ovulation•Parturition•Sperm transport
Other Hormones
B. Melatonin1. Secreted from the pineal gland.
2. Is a modified amino acid
3. Functions to integrate effects of light on reproductive processes.
Other Hormones
C. Human Menopausal Gonadotropin (hMG)1.Anterior pituitary gland
» Secreted in menopause, FSH-like activity
» Isolated from urine
a. Perganol - superovulation
Classification and Properties of Hormone
A.Site of Production
B.Type of action
1. Primary hormone of reproduction (FSH, LH, estradiol, progesterone)
2. Metabolic hormone (thyroxin, insulin, STH)
Classification and Properties of Hormone
• Chemical Structure»Polypeptides - hypothalamic
»Protein - pituitary, gonad
»Steroids - gonad, adrenal
»Fatty acid - many sources, prostaglandins
»Modified amino acid - pineal
Chemical Structure of Hormones
polypeptide modified amino acid protein sex steroid fatty acid
GnRh melatonin LH Estradiol PGF
TRH FSH Progesterone
CRH Prolactin Testosterone
GHRH ACTH
Somatistatin TSH
Oxytocin GH or STH
Relaxin
Inhibin
2
Chemical Structure of HormonesMolecular size of hormones that regulate reproduction
Hormone Molecular
WeightFSH 30,000 to 37,000LH 26,000 to 32,000Prolactin 23,000 to 25,000HCG 37,700eCG 28,000Relaxin 6,500ACTH 4,500Inhibin >10,000Oxytocin 1,007GnRH 1,200Estradiol 300Testosterone 300Progesterone 300PGF 300
2
Chemical Structure of Hormones Cont.
Polypeptide and protein hormonesare made of peptide bonds
NH3
CH
C
HN
HC
C
NH
CH
COO-
R
O
R
O
R
PeptideBond
These hormones can not be given orally!These hormones can not be given orally!
Chemical Structure of Hormones Cont.
SteroidsCHOLESTEROL
PREGNENOLONE
CORTISOL
ADRENAL OVARY OR TESTES
PROGESTERONE
OH-PROGESTERONE
ANDROSTEINDIONE ESTRONE
TESTOSTERONE ESTRADIOL
17α
PROGESTERONE
CORTISOL
These hormones can be given orally!These hormones can be given orally!
Mechanism of Hormone Action
LH
RECEPTOR
ATP cyclic AMP
Protein Kinase
Nucleus
DNAhistones
phosphorylates
mRNA Protein Synthesis(Enzymes)
CholesterolPregnenolone
Testosterone
CELL MEMBRANE
phosphorylationof enzymes in
steroid synthesis
Protein synthesis thatregulates steroid synthesis
(enzymes)
Mitochondria
Protein Hormones(cAMP second messenger)
Protein Hormones(cAMP second messenger)
Adenylate cyclase
Cholesterol
cAMP Second Messenger Hormones
• Anterior Pituitary Hormones»LH, FSH, Prolactin
»STH, ACTH, TSH
• Placental Hormones»HCG, eCG
Protein Hormones (Ca2+ Second Messenger)Protein Hormones (Ca2+ Second Messenger)
GnRH
Receptor
Receptor
GnRH
Receptor
Receptor
G-proteinG-protein
PLC
Phosphotidyl Inositol
DAG
IP3
Endoplasmic Reticulum
R
Ca2+
Ca2+
PKC
LH
SecretoryGranules
Fusion
Plasma Membrane
Plasma Membrane
Ca2+
Calcium Second Messenger Hormones
• GnRH» triggers release of LH in anterior pituitary
• Oxytocin» triggers contractions of smooth muscle
• PGF2
» triggers apoptosis of cell
» inhibition of progesterone synthesis
Steroid Hormone Action
STEROID(estrogen)
Cytoplasm Diffusion?
Cell Membrane
DNA
Receptor
NucleusmRNA
Protein Synthesis
Change in CellPhysiology
UterineGrowth
Feedback Loops
Hypothalamus
Releasing Hormones
Neuro-secretory Cells
Portal Vein
Anterior Pituitary
Gonadotropins: FSH, LH
Blood Stream
GonadsReceptor on Cell Surface
Cyclic AMP inside cell
Steroid Hormone Production
Blood Stream
-
-
Polypeptides
Proteins
Why only effects on target organs[ ]
{TestosteroneEstradiolProgesterone
Bound to Protein