Transcript Lecture_40
May 5, 2014 – Chemical signals and hormones V Announcements: - Final is NOT CUMULATIVE* - In lecture review session (Wed. May 7) - TA led review session (10am – 12pm, Wed. May 14, 151 Everett Lab 1. 2. 3. 4. Pre-lecture quiz Review of sex hormones in males (spermatogenesis) Sex hormones in females (menstrual cycles and pregnancy) Hormone-mediated physiological tradeoffs * I will ask about recurrent themes (e.g. tradeoffs, negative feedback, etc.) True or False: All mammals are viviparous • A.) True • B.) False Upon fertilization and implantation, the degeneration of the corpus luteum is slowed by which hormone in human females? • A.) LH • B.) Estradiol • C.) Progesterone • D.) human chorionic gonadotropin hormone (hCG) Hormone-mediated Tradeoffs Interactions between stress, reproduction and immune function HPG axis Gonads • Male testes produce sperm cells • Female ovaries produce ova • Fertilization – Sperm cell + ovum = zygote • Sex chromosomes – Humans: XX = female, XY = male – Birds: ZW = female, ZZ = male – Many vertebrates lack sex chromosomes entirely Sex Hormones – Released by Gonads • Androgens - e.g., testosterone (“male” hormones) • Estrogens - e.g., estradiol (“female” hormones) • Adult testes release more androgens and ovaries more estrogens • Progestins – also present in both sexes – progesterone prepares uterus and breasts for pregnancy • Adrenal cortex – also releases sex steroids HPG axis & Reproductive System Males Also known as Leydig cells HPG axis & Reproductive System Males Females Figure 48-12 5. Degeneration of corpus luteum Secondary oocyte to oviduct 4. Ovulation Oocytes Follicle cells 3. Maturation of follicle 1. Formation of primary oocytes within follicles 2. Follicle growth Figure 48-13-2 FOLLICULAR PHASE Follicle growth LUTEAL PHASE Ovulation Corpus luteum degeneration Pituitary hormone cycle Hormone levels Ovarian cycle LH FSH 0 7 14 Days 21 28 Figure 48-14 FOLLICULAR PHASE LUTEAL PHASE Ovulation Follicle growth Corpus luteum degeneration Progesterone Estradiol Low Estradiol inhibits LH release Positive feedback on LH Negative feedback on LH, FSH Figure 48-13 FOLLICULAR PHASE Follicle growth LUTEAL PHASE Ovulation Corpus luteum degeneration Pituitary hormone cycle Progesterone Estradiol Hormone levels Ovarian hormone cycle Hormone levels Ovarian cycle LH Menstrual (uterine) cycle Thickness of uterine lining FSH Menstruation 0 7 14 Days 21 28 Tons of Variation among Females. Kathryn Clancy UI - Anthropology [email protected] Pregnancy & hormonal arrest of the menstrual cycle • Human Chorionic gonadotropin Hormone (hCG) – Secreted by the developing embryo – Slows corpus luteum degeneration – Causes the ovary to continue secreting progesterone, arresting the menstral cycle • At later stages of the pregnancy, the placenta also secretes high levels of progesterone Steps of Hormonal Control of Ovarian Cycle 1. 2. 3. 4. 5. GnRh released from hypothalamus. Stimulates release of FSH/LH in ant. Pit. FSH (and to a lesser extent LH) stimulates growth of follicle cells. Follicle cells release E. Low levels of E have negative feedback on GnRH, LH, FSH . . But follicle cells keep growing. Follicle cells get big release lots of E -- positive feedback E has a positive effects on GnRH and LH 6. Hormone surge in LH, FSH, and E. Follicle bursts ovulation 7. burst follicle turns into corpus luteum. It secretes lots of progesterone and some estrogen. 8. increased progesterone causes thickening of endometrium. 9. P and E have a negative feedback on GnRH, LH, and FSH 10. corpus luteum degrades over time (provided no fertilized embryo) 11. P and E drop and the endometrium lining degrades (menstruation) 12. If fertilization, embryo secretes chorionic gonadotropic which maintains corpus luteum (acts like LH) and maintains high levels of P. The endometrium is maintained. The placenta develops and secretes high levels of P. Hormone-mediated Tradeoffs: Interactions between stress, reproduction and immune function Video 1 Testosterone treated Control Territory size Larger Smaller Singing frequency Higher Lower # of aggressive interactions Higher Lower Number of matings Higher Lower Number of offspring Higher Lower Offspring quality Lower Higher Survival Lower Higher Video 2 Montane Urban Breeding season Shorter Longer Aggressiveness Higher Lower Male parental investment Lower Higher Testosterone Higher Lower Cortisol Higher Lower Stress response Higher Lower Casto JM, V Nolan Jr., ED Ketterson. 2001. Steroid hormones and immune function: experimental studies in wild and captive Dark-eyed Juncos. American Naturalist 157:408-420. Testosterone treated Measured: Control 1.) Corticosterone (= Bird cortisol) 2.) Innate Immune function (PHA injection and swelling) 3.) Adaptive Immune function (antibody production) Increased testosterone is associated with elevated levels of stress hormones & a reduction in immune function Testosterone treated Control Loss of winter fat stores Sooner Later Cortisol Higher Lower Stress Response Higher Lower Innate immune response Lower Higher Antibody production Lower Higher Survival Lower Higher In adult humans, females typically exhibit a more pronounced antibody response to vaccination. Why might this be? Why might it be beneficial to vaccinate boys when they are young? 1.) Females exhibited greater antibody and cytokine production following flu vaccination 2.) Antibody production was negatively associated with testosterone levels in males. 3.) Reduced immune response in males was associated with changes in the regulation of genes involved lipid metabolism and biosynthesis. Video 1 Testosterone treated Control Territory size Larger Smaller Singing frequency Higher Lower # of aggressive interactions Higher Lower Number of matings Higher Lower Number of offspring Higher Lower Offspring quality Lower Higher Survival Lower Higher Effects of cortisol on immune function Cortisol negatively impacts: - T-cell proliferation and signaling - Leucocyte proliferation and the inflammatory response. - Development of immune system structures (i.e. thymus)