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May 5, 2014 – Chemical signals and hormones V Announcements: - Final is NOT CUMULATIVE* - In lecture review session (Wed. May 7) - TA led review session.

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Presentation on theme: "May 5, 2014 – Chemical signals and hormones V Announcements: - Final is NOT CUMULATIVE* - In lecture review session (Wed. May 7) - TA led review session."— Presentation transcript:

1 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.Pre-lecture quiz 2.Review of sex hormones in males (spermatogenesis) 3.Sex hormones in females (menstrual cycles and pregnancy) 4.Hormone-mediated physiological tradeoffs * I will ask about recurrent themes (e.g. tradeoffs, negative feedback, etc.)

2 True or False: All mammals are viviparous A.) True B.) False

3 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)

4 Hormone-mediated Tradeoffs Interactions between stress, reproduction and immune function

5 HPG axis

6 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

7 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

8 HPG axis & Reproductive System Males Also known as Leydig cells

9

10 HPG axis & Reproductive System Males Females

11 Figure Follicle cells Oocytes 1. Formation of primary oocytes within follicles 5. Degeneration of corpus luteum 3. Maturation of follicle Secondary oocyte to oviduct 4. Ovulation 2. Follicle growth

12 Figure Ovulation Pituitary hormone cycle Ovarian cycle Follicle growth FOLLICULAR PHASE Corpus luteum degeneration LUTEAL PHASE FSH LH Hormone levels Days

13 Figure Ovulation Follicle growth FOLLICULAR PHASE Corpus luteum degeneration LUTEAL PHASE Estradiol Progesterone Low Estradiol inhibits LH release Positive feedback on LH Negative feedback on LH, FSH

14 Figure Menstrual (uterine) cycle Ovulation Pituitary hormone cycle Ovarian hormone cycle Ovarian cycle Follicle growth FOLLICULAR PHASE Corpus luteum degeneration LUTEAL PHASE Estradiol Progesterone Menstruation FSH LH Hormone levels Thickness of uterine lining Days

15 Tons of Variation among Females. Kathryn Clancy UI - Anthropology

16 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

17 Steps of Hormonal Control of Ovarian Cycle 1. GnRh released from hypothalamus. Stimulates release of FSH/LH in ant. Pit. 2. FSH (and to a lesser extent LH) stimulates growth of follicle cells. 3. Follicle cells release E. 4. Low levels of E have negative feedback on GnRH, LH, FSH.. But follicle cells keep growing. 5. 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.

18 Hormone-mediated Tradeoffs: Interactions between stress, reproduction and immune function

19 Testosterone treated Control Territory sizeLargerSmaller Singing frequencyHigherLower # of aggressive interactionsHigherLower Number of matingsHigherLower Number of offspringHigherLower Offspring qualityLowerHigher SurvivalLowerHigher Video 1

20 Montane Urban Breeding seasonShorterLonger AggressivenessHigherLower Male parental investmentLowerHigher TestosteroneHigherLower CortisolHigherLower Stress responseHigherLower Video 2

21 Testosterone treated Control Measured: 1.) Corticosterone (= Bird cortisol) 2.) Innate Immune function (PHA injection and swelling) 3.) Adaptive Immune function (antibody production) Casto JM, V Nolan Jr., ED Ketterson Steroid hormones and immune function: experimental studies in wild and captive Dark-eyed Juncos. American Naturalist 157:

22 Increased testosterone is associated with elevated levels of stress hormones & a reduction in immune function

23 Testosterone treated Control Loss of winter fat storesSoonerLater CortisolHigherLower Stress ResponseHigherLower Innate immune responseLowerHigher Antibody productionLowerHigher SurvivalLowerHigher

24 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?

25 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.

26 Testosterone treated Control Territory sizeLargerSmaller Singing frequencyHigherLower # of aggressive interactionsHigherLower Number of matingsHigherLower Number of offspringHigherLower Offspring qualityLowerHigher SurvivalLowerHigher Video 1

27 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)


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