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Lecture 13

AN SC 431W Lecture 13: Lecture 13, 14, 15

3 Pages

Animal Science
Course Code
AN SC 431W
Ott Troy

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PUBERTY REVIEW 1. Kisspeptin- neuron likely responsible for responding to numerous metabolic signals (glucose, leptin, fatty acid) and directly activating GnRH neurons 2. Leptin in the blood is a reflection of the amount of body fat/adipose tissue 3. The primary limiting factor controlling the onset of puberty is the inability of the hypothalamus to secrete sufficient quantities of GnRH to cause release of gonadotropins a. Puberty: neurons produce GnRH, taking in a lot of stimuli to determine how to respond/how much GnRH to produce 4. Chronological age is NOT the most important driver for onset of puberty in females a. Must achieve certain body condition and “fatness” 5. Males can mate and ejaculate BEFORE viable sperm are produced 6. From a practical standpoint, age at which a female can support pregnancy without deleterious effects best defines the onset of puberty in females 7. Ability of gonads and/or anterior pituitary to respond to GnRH does NOT control/limit the onset of puberty a. Gonads and pituitary are already ready to do, no need to develop. The hypothalamus secretion of GnRH in sufficient quantities is limiting factor of puberty 8. GnRH is the neuropeptide hormone that drives the onset of puberty 9. Only females exhibit surge release of GnRH a. Both males and females exhibit pulsatory release 10. Defeminization of brain occurs in male due to action of testosterone crossing the blood- brain barrier and being converted to estrogen a. Inhibits formation of surge center PUBERTY KEY POINTS 11. Factors affecting the onset of puberty a. Social cues b. Genetics c. Nutrition level d. Photoperiod (in females) 12. Know average ages of puberty for animals and different breeds 13. Defeminization of the brain in males 14. Surge vs. Tonic centers of brain a. Differences in GnRH release 15. Definition of puberty 16. Pulsatile pattern of hormone secretion 17. Positive/negative feedback and changes around time of puberty REVIEW 1. Gonads are already matured and functioning at birth, don’t need to go through puberty a. If you gave gonads/pituitary GnRH, they would be able to respond and secrete FSH/LH b. Follicles would be able to grow with FSH, and testosterone would be made with LH b.i. Limitation: before puberty, hypothalamus is not developed enough to secrete sufficient quantities of GnRH to elicit these FSH/LH secretions from pituitary 2. Female: at puberty, Tonic center gradually declines sensitivity to negative feedbacktakes more estrogen to inhibit GnRH production. Therefore, estrogen able to cause GnRH release, creating more FSH to initiate more follicle growth a. Pulses more frequentmore follicle gr
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