Lecture 11 Slides

Lecture 11 Slides - Pre-Midterm Review Session Weds Oct 3 2007 at 6PM Hasbrouck 126 Come prepared with specific questions based on the lectures and

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Pre-Midterm Review Session • Weds, Oct 3, 2007 at 6PM • Hasbrouck 126 • Come prepared with specific questions based on the lectures and readings
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Summary from Lecture 10 Summary from Lecture 10 Sperm counts and testosterone levels have been dropping in American men for decades Environmental disruptors may be responsible Hayes’ work has been attacked but shows that atrazine and its derivatives cause gonadal dysgenesis and hermaphroditism at ecologically relevant doses Sexual differentiation is a multistage process: Chromosomal determination: expression of SRY gene causes indifferent gonad to become a testis – Testis determines whether male or female internal ducts will develop – Testicular androgens determine whether genital tubercle will develop into male or female genitalia – Testicular androgens act on the brain to influence dimorphic brain structure and potential for sexual behavior in adulthood Can endocrine disruptors - such as atrazine, PCB’s, etc. - mimic or block these processes?
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Lecture 11 Lecture 11 Determination of sex and sexual preference: can environmental disruptors change the brain as well as the gonads? Politics and Ethics of the use of animals for food, fiber and research
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Can endocrine disruptors interfere with sexual differentiation of the brain?
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Exposure to Environmental Disruptors can affect cognitive sex differences Gioisa et al. 2007 • Pregnant mice drank the following compounds between day 11 of gestation and day 8 postpartum: – Bisphenol A (released by polycarbonate plastics, used in food packaging and tooth sealants; given at 10ug/kg/day - 20% of EPA approved dose) – Methoxychlor (commonly used insecticide, given at 20u/k/day - less than half EPA tolerated dose) – Corn oil vehicle (control group) • Offspring tested for exploratory, maze and open field behavior as juveniles and adults
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NATIONAL TOXICOLOGY PROGRAM CENTER FOR THE EVALUATION OF RISKS TO HUMAN REPRODUCTION EXPERT PANEL EVALUATION OF BISPHENOL A AUGUST 6-8, 2007 • In utero exposure causes neural and behavioral effects when pregnant women and fetuses are exposed • Infants and children risk acceleration in puberty (note that BPA is found in cans of infant formula). • Reproductive effects are considered negligible in general population.
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Error bars Indicate variability (standard error of the mean) Symbols Above shaded bars indicate statistically significant differences
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Sex differences in non-sexual behaviors of juveniles and adults are eliminated by exposure to low doses of bisphenol A and Methoxychlor during fetal life and/or in the mother’s milk
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The developing nervous system is also a The developing nervous system is also a target of target of gonadal gonadal hormones hormones
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Female, perinatal T Female, perinatal DES DES=diethyl stilbesterol, a synthetic estrogen The brain is sexually differentiated by hormones at an early age
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This note was uploaded on 05/18/2008 for the course BIO 105 taught by Professor Adler,irschick,podos during the Fall '08 term at UMass (Amherst).

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Lecture 11 Slides - Pre-Midterm Review Session Weds Oct 3 2007 at 6PM Hasbrouck 126 Come prepared with specific questions based on the lectures and

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