Animal Science 434 Reproductive Physiology Lecture 6 and

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 » minutes and hours • endocrine system

Neuro-endocrine Response

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 (PGF 2 ) » superovulation and embryo transplant (FSH, e. CG) » 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

Exocrine Gland • A gland with ducts that are used for secretion

Hormone • Substance produced by endocrine gland • Acts on cells, tissues or organs at a place • other than where produced Acts as a catalyst.

Endocrine Glands Hypothalamus Pineal Adrenal Ovary Uterus Pituitary Placenta Testes (in bull) Thyroid Pancreas

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

Location of the Hypothalamus and Pituitary Gland

Hypothalamus

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. B. • • Structure short chain polypeptides (3 - 44 amino acids) General Function to cause the release of trophic hormones from the anterior pituitary gland

Releasing Hormones of the Hypothalamus C. Hormones • Gonadotropin releasing hormone (Gn. RH) » 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)

Hypothalamus

Hypothalamus Preoptic nuclei cell Nerve Cells Superior hypophyseal artery Capillary plexus Hypophyseal portal vessels Cells of the Anterior Pituitary • • • LH FSH Prolactin STH TSH ACTH Posterior pituitary Capillary plexus

Anterior Pituitary Hormones A. Structure 1. glycoproteins or proteins B. Hormones 1. gonadotropins » Follicle stimulating hormone » Luteinizing hormone (LH) » Prolactin (FSH)

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 a S • • S b chains are the same b chains differ and give specificity

Supraoptic nuclei cell Nerve Cells Hypothalamus Paraventricular nuclei cell Capillary plexus Anterior Pituitary Posterior pituitary • Oxytocin • ADH

Hypothalamus Nuclei that produce posterior pituitary hormones

Posterior Pituitary Hormones A. Structure • polypeptides (9 amino acids) B. Hormone • Oxytocin - contraction of smooth muscle

Placental Hormones • Equine » Chorionic Gonadotropin (e. CG) Formation of accessory CL and maintains pregnancy • Human Chorionic Gonadotropin (HCG) » Maintains primate CL and pregnancy » Development of the mammary gland in the mother • Placental • Steroids Lactogen (PL) - 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

Steroid Cholesterol 27 -C Synthesis Pregnenolone 21 -C OH Estradiol 18 -C HO 19 -C 21 -C Progesterone Testosterone

Gonadal Steroids Cont. A. General Cont. » Solubility – Bound to a binding protein for transport B. Type of Steroids » » » Androgens - Testosterone Estrogen - Estradiol Progestin - Progesterone

Steroid Cholesterol Synthesis Pregnenolone Mitochondria OH Estradiol HO Smooth ER Progesterone Testosterone

Other Hormones A. Prostaglandins 1. PGF 2

Lipid Hormones - Prostaglandins Fatty Acids Prostaglandins Phospholipids 1. Produced by all tissues - Rate limiting (Phospholipase A 2) of body 2. Can have a local effect on tissues (same tissue Arachidonic Acid - Precursor to Prostaglandins which produced it) Cyclo-oxygenase 3. Rapidly degraded in lungs Aspirin inhibits • Vasodilation • Maintain CL • Ovulation • Implantation PGE 2 PGF 2 • Vasoconstriction • CL regression • Ovulation • Parturition • Sperm transport

Other Hormones B. Melatonin 1. 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 (h. MG) 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 Gn. Rh melatonin TRH CRH GHRH Somatistatin Oxytocin protein sex steroid fatty acid LH Estradiol PGF 2 FSH Progesterone Prolactin Testosterone ACTH TSH GH or STH Relaxin Inhibin

Chemical Structure of Hormones Molecular size of hormones that regulate reproduction Hormone FSH LH Prolactin HCG e. CG Inhibin Relaxin ACTH Oxytocin Gn. RH Estradiol Testosterone Progesterone PGF 2 Molecular Weight 30, 000 to 37, 000 26, 000 to 32, 000 23, 000 to 25, 000 37, 700 28, 000 >10, 000 6, 500 4, 500 1, 007 1, 200 300 300

Chemical Structure of Hormones Cont. Polypeptide and protein hormones are made of peptide bonds These hormones can not be given orally!

Chemical Structure of Hormones Cont. Steroids PROGESTERONE CORTISOL These hormones can be given orally!

Mechanism of Hormone Action

Mechanism of Hormone Action

Receptor Structure

Mechanism of Hormone Action Protein Hormones (c. AMP second messenger) G Adenylate cyclase phosphorylation of enzymes in steroid synthesis Mitochondria Cholesterol Protein synthesis that regulates steroid synthesis (enzymes)

c. AMP Second Messenger Hormones • Anterior Pituitary Hormones • Placental Hormones » LH, FSH, Prolactin » STH, ACTH, TSH » HCG, e. CG

Protein Hormones (Ca 2+ Second Messenger) Gn. RH Ca Receptor Gn. RH G-protein Plasma Membrane Phosphotidyl Inositol DAG PLC IP 3 Ca R Ca PKC 2+ 2+ Endoplasmic Reticulum Secretory Granules Fusion Plasma Membrane LH 2+

Calcium Second Messenger Hormones • • • Gn. RH » triggers release of LH in anterior pituitary Oxytocin » triggers contractions of smooth muscle PGF 2 » triggers apoptosis of cell » inhibition of progesterone synthesis

Steroid Hormone Action Uterine Growth

Hypothalamus Feedback Loops Neuro-secretory Cells Releasing Hormones Polypeptides Portal Vein - Anterior Pituitary Gonadotropins: FSH, LH Proteins Blood Stream Gonads Receptor on Cell Surface only effects on [ Why ] target organs Cyclic AMP inside cell Steroid Hormone Production { Testosterone Estradiol Progesterone Blood Stream Bound to Protein