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 quiz2. 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.)
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 TradeoffsInteractions 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 SystemMales
Also known as Leydig cells
HPG axis & Reproductive SystemMales Females
Figure 48-12
FolliclecellsOocytes
1. Formation of primaryoocytes within follicles
5. Degeneration ofcorpus luteum
3. Maturation offollicle
Secondary oocyteto oviduct
4. Ovulation
2. Follicle growth
Figure 48-13-2
Ovulation
Pituitaryhormonecycle
Ovariancycle
Follicle growthFOLLICULAR PHASE
Corpus luteum degenerationLUTEAL PHASE
FSH
LH
Hor
mon
e le
vels
Days0 7 14 21 28
Figure 48-14
OvulationFollicle growth
FOLLICULAR PHASECorpus luteum degeneration
LUTEAL PHASE
Estradiol
Progesterone
Low Estradiol inhibits LH release
Positive feedbackon LH
Negative feedbackon LH,FSH
Figure 48-13
Menstrual(uterine)cycle
Ovulation
Pituitaryhormonecycle
Ovarianhormonecycle
Ovariancycle
Follicle growthFOLLICULAR PHASE
Corpus luteum degenerationLUTEAL PHASE
EstradiolProgesterone
Menstruation
FSH
LH
Hor
mon
e le
vels
Hor
mon
e le
vels
Thic
knes
s of
uter
ine
linin
g
Days0 7 14 21 28
Tons of Variation among Females.Kathryn ClancyUI - [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. 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 LH6. Hormone surge in LH, FSH, and E. Follicle bursts ovulation7. 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 FSH10. 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
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 1
Montane Urban
Breeding season Shorter Longer
Aggressiveness Higher Lower
Male parental investment Lower Higher
Testosterone Higher Lower
Cortisol Higher Lower
Stress response Higher Lower
Video 2
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. 2001. Steroid hormones and immune function: experimental studies in wild and captive Dark-eyed Juncos. American Naturalist 157:408-420.
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.
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 1
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)
