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Lecture 4

Lecture 4 - Female Sexual Behavior

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Emis Akbari

PSY395H5 – Hormones and Behavior Lecture 3 – October 4, 2013 Female Sexual Behavior Introduction th  Relatively little known until Century o Lack of interest o Social biases? o Too complex?  Cyclic; ovariectomy difficult  First fact known – removal of ovaries stops mating  How do ovaries influence female sex behavior?  Need to know what ovaries do, when they do it o Remove ovaries and look at microscopically Estrous Cycle  Unlike males, most females not always ready to mate  In many rodents, this cycle occurs every few days
  In many larger animals, this cycle occurs seasonally  Vaginal Cytology Assay (1917)
 o Cell types found in vaginal lining vary according to ovarian function
  Gently swab vagina  Smear on glass slide  Stain cells
  Look at under microscope  In rats, cell types cycle every 4-5 days o Estrus – cornified (crunchy) epithelial cells o Diestrus – mostly leukocytes (white blood cells) o Proestrus – round, nucleated epithelial cells Menstrual Cycle  In primates, called menstrual cycle o “Moon”
 o Not called estrus cycle, because mating (estrus)  Not confined to a particular phase
 o Surge of GnRH, surge of estradiol, ovulation o Menstruation when Estrogen + Progesterone lowest o Endometrial (outermost) layer of uterus shed o Blood vessels near surface now exposed and leak What Comes From the Ovary For Mating?  Estrogen does not induce mating in all females
 o About 40% of rats/mice do not mate with estrogen alone o PROGESTERONE  Prepares uterus for pregnancy (pro-gestational)  Synergizes with estradiol to promote mating Incentives for Female Sexual Behavior?  Procreation  Security PSY395H5 – Hormones and Behavior Lecture 3 – October 4, 2013  Feels good Components of Female Mating Behaviors  (1) Attractivity
 o “Stimulus value” (incentive) of the female to a given male o Test by recording how long a male spends with a female o Enhanced by hormones associated with ovulation  Estradiol – so a particular female can be more or less attractive to a male  What does estradiol change to increase attractivity? o Visual cues – in primates, peri-genital skin swellings o Chemosensory cues – urinary and vaginal secretions  Detected by main or accessory olfactory systems o Behavioral cues seen from far distance
 o How about changes that occur as a result of lack of estrogen?  Weight gain
  Hair growth  Disappearance of waist  With these changes – does the motivation to seek out sexual behavior change? Role of Testesterone....  Proceptive behaviors
 o Attract male and maintain his interest o Primates – presentations of genitalia to male o Rats  Hopping away, waiting, moving back to male (hop-dart) •ear-wiggling (video)  (2) Proceptivity o Extent to which female initiates copulation o Underlying motivational state  Bar-press faster to get male  Related to circulating estradiol o Females investigate male’s genitalia o Overt proceptive behaviors  (3) Receptivity o State of females’ responsiveness to sexual contact by male o The consummatory phase of copulation
 o Reactions that are necessary and sufficient for fertile copulation  Lordosis (mating posture) o Arch back
 o Primary posture of sexual receptivity in rodents allows penetration of penis (intromission)  Receptivity in rats
 o Measured by ratio of lordosis responses/mounts by male o Lordosis Quotient (LQ) o Example: For 40 mounts, a female exhibited lordosis 20 times. Her lordosis quotient it o 20 / 40 = 0.5  Receptivity in most animals depends on circulating estradiol o OVEXed females not receptive
 PSY395H5 – Hormones and Behavior Lecture 3 – October 4, 2013 o Many are receptive if given estradiol injection Description of Female Mating Behavior  Primates (chimps, marmosets):
 o Highly stereotyped – what does this mean? o Vulva pointed back and outward
 o Male bends over her back, hands on shoulders, intromits o After multiple intromissions/thrusts, ejaculation, dismount o Mutual or solitary examining and grooming of genitals  Primates (gorilla, humans, bonobos): o Not highly stereotyped o Multiple positions
 o Also, sex activity not limited to particular time  Unrelated to estradiol?? Is Female Sexual Behavior in Humans Independent of Ovarian Hormones?  Studies of heterosexual, monogamous, married couples  Based on self-reports of copulation
  Excess hormones (E, P, or T) do not increase copulation o Women on “pill” or not  Erotic thoughts, autostimulation increase at ovulation  In lesbian couples, increases in activity around ovulation o Eliminates influence of male (pheromones etc)  Androgens play a role
 o From adrenals and a little from ovaries
 o T levels correlate with sexual desire and thoughts o Androgens restore sexual desire in OVEXed women Role of Female in Mating  Before 1970s, females seen as passive recipients of male attention  In reality, female have very active role •often initiate copulation
 •sex drive equals or exceeds males’ •high selectivity for mates  •relates to evolutionary pressures  If test in natural settings, females control pace of mating •test rodents in groups
 •female receive intromission, run away, come back  •not usually back to the same male, either  If females allowed to pace mating, it looks very different •stimulation she receives differs
 •intervals between intromissions longer (3 vs 1 min) •female initiated contact results in intromission  •(90% vs 3%) Other Social Influences on Female Cycles  Whitten Effect PSY395H5 – Hormones and Behavior Lecture 3 – October 4, 2013 o Females in males cages, 25% should mate that night o Few mate on first two days, most mate on third day o Why females come into estrus after three days?  Urine from males produces this effect  Effects lost if males castrated  Bruce Effect o Pregnant female mice exposed to novel males
 (not the mate) terminate their pregnancy in 3-6 days o If same strain, 25% pregnancies terminate
 o If different strain, 80% pregnancies terminate o Requires just 12 hours of exposure to novel male o She then goes into estrus and mates again  Bruce Effect o Advantage? To female if f sire gone
 o Maybe he had bad genes o Novel male may kill pups o Female cuts her losses  Vandenbergh Effect 1 o Females exposed to adult males - puberty sooner o Puberty ~20 days earlier in mice
 •puberty ~5-10 days earlier in rats
  Male urine alone can produce this o Male must be gonadally intact o Increases DA in females’ hypothalamus o May act by increasing LH  Vandenbergh Effect 2 o Females living with other females- puberty later o Reach puberty sooner if living alone o Pheromone-based
 o Estrogen-dependent o May act by suppressing GnRH  What about human cycles?
 o 1970s – 7-8 months cohabitation produces o Synchrony of menstrual cycle
 o Maybe the most perpetuated ARTIFACT in behavioral endocrinology  Studies flawed
  Self-reports inaccurate •improper statistics
 •can’t be replicated
 •only occurs in some women  Who are extra-sensitive  Regardless, are there pheromones in humans?? o Maybe... o Two possible pheromones in women
 o Absorbent pads worn at different stages of cycle o Pads wiped under noses of other women  Women could not detect odors in pads
 o If donor pad from follicular phase, cycle shortened o If donor pad from ovulatory phase, cycle lengthen Neural Structures Mediating Female Sexual Behaviors PSY395H5 – Hormones and Behavior Lecture 3 – October 4, 2013  Best understood for lordosis:  1) Hypothalamus
  Ventromedial Nucleus (VMN) o lesions reduce lordosis
 o cutting fibers leaving VMN also reduce it o these fibers go down to midbrain  2) Midbrain
 o Central Gray (Periaqueductal Gray) o lesions reduce lordosis
 o CG receives hormone info from VMN o CG receives sensory info from spinal cord  3) Medulla
 o reticular formation controls spinal motorneurons o for movement of back, tail, limbs  4) Spinal Cord o receives somatosensory information o sends up to brain o also gets information from brain, sends to motorneurons
 o so, primary receiver of sensory information and primary mediator of motor information  Hormonal influences on these structures:
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