Chapter 11 Hormones and Sex What’s Wrong with the Mamawawa <ul><li>This multimedia product and its contents are protected ...
Developmental and Activational Effects of Sex Hormones <ul><li>Developmental – “organizational” - influencing the developm...
Glands <ul><li>Exocrine – Release chemicals into ducts which carry them to their targets.  </li></ul><ul><ul><li>Sweat gla...
 
Gonads <ul><li>Male testes produce sperm cells </li></ul><ul><li>Female ovaries produce ova </li></ul><ul><ul><li>Sperm an...
Sex Hormones – Released by Gonads <ul><li>Androgens - e.g., testosterone  </li></ul><ul><li>Estrogens - e.g., estradiol  <...
Hormones <ul><li>Steroids </li></ul><ul><ul><li>Synthesized from cholesterol (fat) </li></ul></ul><ul><ul><li>Fat-soluble ...
Hormones of the Pituitary <ul><li>“Master gland” </li></ul><ul><li>Tropic hormones influence the release of hormones by ot...
 
 
Cyclic Vs Steady Gonadal Hormone Levels <ul><li>Female hormones go through a 28-day cycle, the menstrual cycle </li></ul><...
Control of the Pituitary by the Hypothalamus <ul><li>Posterior – neural input from hypothalamus </li></ul><ul><ul><li>Vaso...
Hypothalamic Releasing Hormones <ul><li>Releasing and inhibiting hormones control production and release of the anterior p...
Regulation of Hormone Levels <ul><li>Neural  </li></ul><ul><ul><li>All endocrine glands (except the anterior pituitary) re...
 
Sexual Development <ul><li>We are dimorphic – exist in 2 forms </li></ul><ul><li>Initially there is a primordial gonad </l...
 
Sexual Development <ul><li>6-weeks post-conception:  </li></ul><ul><ul><li>H-Y antigen > testes  </li></ul></ul><ul><ul><l...
Sexual Development <ul><li>6-weeks: gonads develop </li></ul><ul><li>3 rd  prenatal month: differentiation of ducts </li><...
 
A terminology note <ul><li>Ovariectomy – removal of ovaries </li></ul><ul><li>Orchidectomy – removal of testes </li></ul><...
Sexual Development <ul><li>External reproductive structures – genitalia – develop from one bipotential precursor </li></ul...
 
Sex Differences in the Mammalian Brain <ul><li>Pfeiffer (1936) – gonadectomized and implanted gonads in neonatal rats </li...
Aromatization and Sex Differences in the Brain <ul><li>What masculinizes the brain? </li></ul><ul><li>Sex steroids are all...
Evidence that Estradiol (E) Masculinizes the Neonatal Brain <ul><li>Neonatal injections of E masculinize </li></ul><ul><li...
Alpha fetoprotein <ul><li>In blood during perinatal period - protects the female brain from E </li></ul><ul><li>Binds to c...
Sex Differences in the Brain: What Do They Mean? <ul><li>Many differences, but their significance is not known </li></ul><...
Perinatal Hormones and Behavioral Development <ul><li>Masculinize – promoting male behavior, mounting, etc. </li></ul><ul>...
Puberty <ul><li>Fertility achieved, secondary sex characteristics develop </li></ul><ul><ul><li>Features that distinguish ...
 
Puberty <ul><li>Relative levels of androgens and estrogens determine whether male or female features develop </li></ul><ul...
Anne S. <ul><li>Knowing how normal development occurs, you should be able to understand what could cause abnormal sexual d...
Anne S. <ul><li>Anne is chromosomally male, XY </li></ul><ul><li>Internalized testes, but no ovaries </li></ul><ul><li>Hor...
Adrenogenital Syndrome <ul><li>Androgenic insensitivity leads an XY individual to look female (Anne S.) </li></ul><ul><li>...
John/Joan <ul><li>A surgeon’s error led one of a pair of male twins to be raised as a girl </li></ul><ul><ul><li>Artificia...
Male Reproduction-Related Behavior and Testosterone (T) <ul><li>Effects of orchidectomy  Bremer (1959)   </li></ul><ul><ul...
Female Reproduction-Related Behavior and Gonadal Hormones <ul><li>Rats and guinea pigs – surges of estrogen and progestero...
Human Female Sexuality and Androgens <ul><li>T increases the proceptivity of ovariectomized and adrenalectomized female rh...
Anabolic Steroids <ul><li>Anabolic – growth-promoting </li></ul><ul><li>No firm scientific evidence that muscularity and s...
Neural Mechanisms of Sexual Behavior <ul><li>Sexually dimorphic nucleus (SDN) </li></ul><ul><ul><li>medial preoptic area o...
Medial Preoptic Area of the Hypothalamus <ul><li>Contains the SDN </li></ul><ul><li>Destruction abolishes sexual behavior ...
Ventromedial Nucleus of the Hypothalamus <ul><li>Contains circuits critical for female rat sexual behavior </li></ul><ul><...
Sexual Orientation <ul><li>Heterosexual – sexually attracted to members of the other sex </li></ul><ul><li>Homosexual – se...
Sexual Orientation <ul><li>Genetic basis established </li></ul><ul><li>No differences in hormone levels </li></ul><ul><li>...
Sexual Body Type, Orientation, and Identity <ul><li>All 3 are independent entities </li></ul><ul><li>Consider Anne S. – ch...
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Pinel basics ch11

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Pinel basics ch11

  1. 1. Chapter 11 Hormones and Sex What’s Wrong with the Mamawawa <ul><li>This multimedia product and its contents are protected under copyright law. The following are prohibited by law: </li></ul><ul><li>any public performance or display, including transmission of any image over a network; </li></ul><ul><li>preparation of any derivative work, including the extraction, in whole or in part, of any images; </li></ul><ul><li>any rental, lease, or lending of the program. </li></ul>
  2. 2. Developmental and Activational Effects of Sex Hormones <ul><li>Developmental – “organizational” - influencing the development of anatomical, physiological and behavioral characteristics that differentiate the sexes </li></ul><ul><li>Activational – activating reproduction-related behavior in mature individuals </li></ul>
  3. 3. Glands <ul><li>Exocrine – Release chemicals into ducts which carry them to their targets. </li></ul><ul><ul><li>Sweat glands, for example </li></ul></ul><ul><li>Endocrine – Ductless. Release hormones directly into the circulatory system </li></ul><ul><ul><li>Primary function is hormone release </li></ul></ul>
  4. 5. Gonads <ul><li>Male testes produce sperm cells </li></ul><ul><li>Female ovaries produce ova </li></ul><ul><ul><li>Sperm and ova each have 23 chromosomes </li></ul></ul><ul><li>Fertilization </li></ul><ul><ul><li>Sperm cell + ovum = zygote </li></ul></ul><ul><ul><li>23 pairs of chromosomes </li></ul></ul><ul><li>X and Y – sex chromosomes </li></ul><ul><ul><li>XX = female, XY = male </li></ul></ul>
  5. 6. Sex Hormones – Released by Gonads <ul><li>Androgens - e.g., testosterone </li></ul><ul><li>Estrogens - e.g., estradiol </li></ul><ul><li>Adult testes tend to release more androgens and ovaries tend to release more estrogens </li></ul><ul><li>Progestins – also present in both sexes </li></ul><ul><ul><li>progesterone prepares uterus and breasts for pregnancy </li></ul></ul><ul><li>Adrenal cortex – also releases sex hormones </li></ul>
  6. 7. Hormones <ul><li>Steroids </li></ul><ul><ul><li>Synthesized from cholesterol (fat) </li></ul></ul><ul><ul><li>Fat-soluble – able to enter cells and bind to receptors in cytoplasm or nucleus </li></ul></ul><ul><li>Amino acid derivatives </li></ul><ul><ul><li>Epinephrine, for example (adrenal medulla) </li></ul></ul><ul><li>Peptides and proteins </li></ul><ul><ul><li>Short and long chains of amino acids </li></ul></ul>
  7. 8. Hormones of the Pituitary <ul><li>“Master gland” </li></ul><ul><li>Tropic hormones influence the release of hormones by other glands </li></ul><ul><li>Posterior pituitary – hormones synthesized in the hypothalamus </li></ul><ul><li>Anterior pituitary – tropic hormones </li></ul>
  8. 11. Cyclic Vs Steady Gonadal Hormone Levels <ul><li>Female hormones go through a 28-day cycle, the menstrual cycle </li></ul><ul><li>Male hormone levels constant </li></ul><ul><li>Anterior pituitary activity is controlled by the hypothalamus </li></ul><ul><li>The hypothalamus determines whether or not hormone levels cycle </li></ul>
  9. 12. Control of the Pituitary by the Hypothalamus <ul><li>Posterior – neural input from hypothalamus </li></ul><ul><ul><li>Vasopressin – antidiuretic hormone </li></ul></ul><ul><ul><li>Oxytocin – labor and lactation </li></ul></ul><ul><ul><li>Synthesized in hypothalamic paraventricular and supraoptic nuclei </li></ul></ul><ul><ul><li>These nuclei have terminals in the posterior pituitary </li></ul></ul><ul><li>Anterior pituitary – hypothalamopituitary portal system carries hormones from the hypothalamus to the anterior pituitary </li></ul>
  10. 13. Hypothalamic Releasing Hormones <ul><li>Releasing and inhibiting hormones control production and release of the anterior pituitary </li></ul><ul><li>All releasing and tropic hormones are peptides </li></ul>Gonadotropins (FSH and LH) – stimulate gonads Gonadotropin-releasing hormone Thyrotopin – stimulates thyroid Thyrotropin-releasing hormone Anterior pituitary Hypothalamus
  11. 14. Regulation of Hormone Levels <ul><li>Neural </li></ul><ul><ul><li>All endocrine glands (except the anterior pituitary) receive neural signals </li></ul></ul><ul><ul><li>From cerebral or autonomic neurons </li></ul></ul><ul><li>Hormonal </li></ul><ul><ul><li>Tropic hormones, negative feedback </li></ul></ul>
  12. 16. Sexual Development <ul><li>We are dimorphic – exist in 2 forms </li></ul><ul><li>Initially there is a primordial gonad </li></ul><ul><ul><li>Cortex – potential to be ovary </li></ul></ul><ul><ul><li>Medulla – potential to be a testis </li></ul></ul><ul><li>If XY, Y triggers the synthesis of H-Y antigen and promotes development of the medulla </li></ul><ul><li>No H-Y antigen, cortex develops into ovary </li></ul>
  13. 18. Sexual Development <ul><li>6-weeks post-conception: </li></ul><ul><ul><li>H-Y antigen > testes </li></ul></ul><ul><ul><li>No H-Y antigen > ovaries </li></ul></ul><ul><li>Both sexes begin with 2 sets of reproductive ducts </li></ul><ul><ul><li>Wolffian system – male – seminal vesicles, vas deferens </li></ul></ul><ul><ul><li>Mullerian system – female – uterus, vagina, fallopian tubes </li></ul></ul><ul><li>Differentiation occurs in the 3 rd prenatal month </li></ul>
  14. 19. Sexual Development <ul><li>6-weeks: gonads develop </li></ul><ul><li>3 rd prenatal month: differentiation of ducts </li></ul><ul><ul><li>Testes produce testosterone and Mullerian-inhibiting substance </li></ul></ul><ul><ul><ul><li>Wolffian system develops, Mullerian degenerates, testes descend </li></ul></ul></ul><ul><ul><li>No testes – no testicular hormones </li></ul></ul><ul><ul><ul><li>Mullerian system develops, Wolffian degenerates </li></ul></ul></ul>
  15. 21. A terminology note <ul><li>Ovariectomy – removal of ovaries </li></ul><ul><li>Orchidectomy – removal of testes </li></ul><ul><li>Gonadectomy or castration – removal of gonads, either ovaries or testes </li></ul><ul><li>Such procedures are often used to study the effects of sex hormones </li></ul>
  16. 22. Sexual Development <ul><li>External reproductive structures – genitalia – develop from one bipotential precursor </li></ul><ul><li>Differentiation occurs in 2 nd month </li></ul><ul><li>Testosterone > male </li></ul><ul><li>No testosterone > female </li></ul>
  17. 24. Sex Differences in the Mammalian Brain <ul><li>Pfeiffer (1936) – gonadectomized and implanted gonads in neonatal rats </li></ul><ul><ul><li>Gonadectomy > cyclic hormone release </li></ul></ul><ul><ul><li>Transplant of testes or ovaries > steady </li></ul></ul><ul><ul><ul><li>Perinatal hormones lead to male pattern </li></ul></ul></ul><ul><li>Why do both ovaries and testes lead to male pattern? </li></ul>
  18. 25. Aromatization and Sex Differences in the Brain <ul><li>What masculinizes the brain? </li></ul><ul><li>Sex steroids are all derived from cholesterol and are readily converted from one to the other </li></ul><ul><ul><li>Aromatize testosterone > estradiol </li></ul></ul><ul><li>Evidence suggests that estradiol masculinizes the brain </li></ul>
  19. 26. Evidence that Estradiol (E) Masculinizes the Neonatal Brain <ul><li>Neonatal injections of E masculinize </li></ul><ul><li>Dihydrotestosterone can’t be converted to E – doesn’t masculinize </li></ul><ul><li>Block aromatization or E receptors – interferes with masculinizing effects of testosterone </li></ul><ul><li>Why doesn’t E masculinize female brains? </li></ul>
  20. 27. Alpha fetoprotein <ul><li>In blood during perinatal period - protects the female brain from E </li></ul><ul><li>Binds to circulating E, so none gets to the brain </li></ul><ul><li>How does E get into male brain? </li></ul><ul><li>In males, testosterone enters the brain and then is converted to E </li></ul>
  21. 28. Sex Differences in the Brain: What Do They Mean? <ul><li>Many differences, but their significance is not known </li></ul><ul><li>Links between structural differences and functional differences have not been established </li></ul>
  22. 29. Perinatal Hormones and Behavioral Development <ul><li>Masculinize – promoting male behavior, mounting, etc. </li></ul><ul><li>Defeminize – preventing female behavior, lordosis </li></ul><ul><li>Perinatal T masculinizes and defeminizes </li></ul><ul><li>Neonatal castration of male rats – feminizes and demasculinizes </li></ul>
  23. 30. Puberty <ul><li>Fertility achieved, secondary sex characteristics develop </li></ul><ul><ul><li>Features that distinguish sexually mature men and women </li></ul></ul><ul><li>Increase in release of anterior pituitary hormones </li></ul><ul><ul><li>Growth hormone – acts on bone and muscle </li></ul></ul><ul><ul><li>Gonadoptrophic hormone </li></ul></ul><ul><ul><li>Adrenocorticotrophic hormone </li></ul></ul>
  24. 32. Puberty <ul><li>Relative levels of androgens and estrogens determine whether male or female features develop </li></ul><ul><li>Androstenedione – androgen necessary for the growth of axillary and pubic hair in both sexes </li></ul>
  25. 33. Anne S. <ul><li>Knowing how normal development occurs, you should be able to understand what could cause abnormal sexual development </li></ul><ul><li>Why might a woman not cycle and have no pubic or axillary hair? </li></ul><ul><ul><li>What determines whether male or female hormone patterns develop? </li></ul></ul><ul><ul><li>What causes the growth of pubic and axillary hair? </li></ul></ul>
  26. 34. Anne S. <ul><li>Anne is chromosomally male, XY </li></ul><ul><li>Internalized testes, but no ovaries </li></ul><ul><li>Hormone levels are those of a man </li></ul><ul><li>What happened? </li></ul><ul><li>Androgenic insensitivity syndrome </li></ul><ul><ul><li>Normal male androgen levels, but no response to them </li></ul></ul><ul><ul><li>She does respond to estrogens, so she effectively has more estrogens than androgens – leading to the development of female secondary sex characteristics </li></ul></ul>
  27. 35. Adrenogenital Syndrome <ul><li>Androgenic insensitivity leads an XY individual to look female (Anne S.) </li></ul><ul><li>Andrenogenital Syndrome is caused by congenital adrenal hyperplasia </li></ul><ul><ul><li>Too little cortisol leads to compensatory excessive release of adrenal androgens </li></ul></ul><ul><ul><li>No problem for males </li></ul></ul><ul><ul><li>May masculinize female genitalia and behavior – surgical and hormonal treatments needed at puberty </li></ul></ul>
  28. 36. John/Joan <ul><li>A surgeon’s error led one of a pair of male twins to be raised as a girl </li></ul><ul><ul><li>Artificial vagina created </li></ul></ul><ul><ul><li>Estrogen administered at puberty </li></ul></ul><ul><li>John/Joan never felt or acted like a girl – indicates that the key to one’s gender is in the brain </li></ul><ul><li>John/Joan chose to become John later in life, but never recovered from the ordeal </li></ul><ul><li>John took his life in May of 2004 </li></ul>
  29. 37. Male Reproduction-Related Behavior and Testosterone (T) <ul><li>Effects of orchidectomy Bremer (1959) </li></ul><ul><ul><li>Reduced sexual interest and behavior </li></ul></ul><ul><ul><li>Rate and degree of loss varies </li></ul></ul><ul><ul><li>Still have adrenal T </li></ul></ul><ul><li>Level of male sexuality is NOT correlated with T levels </li></ul><ul><li>Increasing male T levels does NOT increase sex drive </li></ul>
  30. 38. Female Reproduction-Related Behavior and Gonadal Hormones <ul><li>Rats and guinea pigs – surges of estrogen and progesterone initiate estrus, a period of fertility and receptivity </li></ul><ul><li>Women – sexual motivation and behavior not tied to cycle </li></ul><ul><li>Sex drive may be under androgenic control </li></ul>
  31. 39. Human Female Sexuality and Androgens <ul><li>T increases the proceptivity of ovariectomized and adrenalectomized female rhesus monkeys </li></ul><ul><li>Correlations seen between sexual motivation and T </li></ul><ul><li>T found to rekindle sexual motivation in ovariectomized and adrenalectomized women </li></ul>
  32. 40. Anabolic Steroids <ul><li>Anabolic – growth-promoting </li></ul><ul><li>No firm scientific evidence that muscularity and strength are increased </li></ul><ul><li>Sex-related side effects </li></ul><ul><li>High circulating hormones cause a reduction of natural release </li></ul><ul><ul><li>Men - testicular atrophy, sterility, gynecomastia (breast growth in men) </li></ul></ul><ul><ul><li>Women – amenorrhea (cessation of menstruation), sterility, hirsutism (excessive growth of body hair) </li></ul></ul>
  33. 41. Neural Mechanisms of Sexual Behavior <ul><li>Sexually dimorphic nucleus (SDN) </li></ul><ul><ul><li>medial preoptic area of rat hypothalamus </li></ul></ul><ul><ul><li>larger in males, due to estradiol shortly after birth </li></ul></ul><ul><ul><li>size of male SDN correlated with T levels and aspects of sexual activity </li></ul></ul><ul><li>Nuclei in preoptic, suprachiasmatic, and anterior regions of the hypothalamus are larger in men than in women </li></ul>
  34. 42. Medial Preoptic Area of the Hypothalamus <ul><li>Contains the SDN </li></ul><ul><li>Destruction abolishes sexual behavior of all mammalian males studied, but does not affect female sexual behaviors females </li></ul><ul><li>Stimulation elicits copulatory behaviors </li></ul>
  35. 43. Ventromedial Nucleus of the Hypothalamus <ul><li>Contains circuits critical for female rat sexual behavior </li></ul><ul><li>Lesion eliminates lordosis </li></ul><ul><li>Microinjections of E and progesterone induce estrus </li></ul><ul><li>Lesions of periaqueductal gray (PAG) or the tracts to it eliminate lordosis </li></ul>
  36. 44. Sexual Orientation <ul><li>Heterosexual – sexually attracted to members of the other sex </li></ul><ul><li>Homosexual – sexually attracted to members of the same sex </li></ul><ul><li>Bisexual – sexually attracted to members of both sexes </li></ul>
  37. 45. Sexual Orientation <ul><li>Genetic basis established </li></ul><ul><li>No differences in hormone levels </li></ul><ul><li>Animal research suggests altered hormone levels during development may play a role, but there is no direct human evidence of this </li></ul>
  38. 46. Sexual Body Type, Orientation, and Identity <ul><li>All 3 are independent entities </li></ul><ul><li>Consider Anne S. – chromosomally a man, but a woman in every other way </li></ul><ul><li>Consider John/Joan – a man’s brain in a woman’s body </li></ul><ul><li>How would you define male and female? </li></ul>

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