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

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 System

Males

Also known as Leydig cells

HPG axis & Reproductive System

Males 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 growth

FOLLICULAR PHASE

Corpus luteum degeneration

LUTEAL PHASE

FSH

LH

Ho

rmo

ne

leve

ls

Days0 7 14 21 28

Figure 48-14

OvulationFollicle growth

FOLLICULAR PHASE

Corpus 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 growth

FOLLICULAR PHASE

Corpus luteum degeneration

LUTEAL PHASE

Estradiol

Progesterone

Menstruation

FSH

LH

Ho

rmo

ne

le

ve

lsH

orm

on

e l

ev

els

Th

ick

ne

ss

of

ute

rin

e l

inin

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)