1. Neuro-endocrine control of reproduction in sheepZeleke MekuriawEIAR-DBARC-ICARDA-ILRI (LIVES)-FAO Training on Reproductionin Sheep and Goat, Debre Berhan, Ethiopia, 13-15 October 2014

2. Outline Introduction Hypothalamic-pituitary-Gonadal axis (HPG) Hypothalamus Production and release of GnRH Function of GnRH The Pituitary gland Functions & regulations of gonadotrophin hormones Gonadal (steroid) Hormones Hormone from Pineal gland Summary of integration of organs & hormones to regulate reproduction 2 3. Introduction The nervous system &endocrine systems workjointly One affects the other (NS -byproducing neurotransmitters;ES-feedback mechanisms) Maintain homeostasis(internal stability) 4. Hypothalamic-pituitary-Gonadal axis (HPG) The reproductive process governed byHPG axis A complex neuro-endocrine system Composed of 3 anatomically &functionally distinct structures Regulate reproduction withcoordination 5. Hypothalamus Part of brain Has close apposition withpituitary gland Produces GnRH(a mastermolecule- neurotransmitter) Controls the function ofpituitary gland 6. Production and release of GnRH The hypothalamic area thatcontrols reproduction isrepresented by scatteredneurons producing GnRH. The dispersed GnRHneurons, collectively calledGnRH pulse generator. GnRH pulse generatorreceives and integratesendogenous cues andexternal stimuli. 7. Function of GnRH Controls gonadal activity byregulating synthesis & release ofpituitary gonadotropins (LH & FSH). Pulsatile GnRH secretion induces anidentical pattern of LH secretion &increases FSH synthesis. Leads to gametogenesis &steroidogenesis 8. Pituitary gland A master gland Located at the base of brain Anterior & posterior lobes Anterior- major source of reproductive hormones Produces FSH & LH (tropic hormones-affect other glands) Function both in male & female Role in gametogenesis & steroidogenesis 9. Functions and regulations of gonadotropin hormones LH: For the synthesis oftestosterone For final maturation of ovum For ovulation of matured egg For the formation andmaintenance of CL Pulsatile (tonic) and surge(burst) FSH: spermatogenesis in male Follicular growth in female 10. Gonadal Hormones -steroid hormones In Female Ovarian Hormones Oestradiol From matured follicle Secondary sexual characteristics sexual desire in female Progesterone From CL Maintenance of pregnancy 11. Gonadal Hormones -steroid hormones Inhibin From dominant follicle Inhibits secretion of FSH Uterine Hormone Prostaglandin Luteolysis (disintegration of CL) 12. Integration among structural and hormonal changes duringthe oestrous cycleEstrusEstrusCL0 2 4 6 8 10 12 14 16 17Day of the Estrous CycleLH surgePGF2LH surgeFolliclesovulationovulationLH pulses LH pulses 13. Gonadal Hormones -steroid hormones In Male Testosterone Produced from ledying cells of testis Action of LH required Role: Libido Secondary sexual characteristics Musculature Androgen binding proteins Produced by sertoli cells Development of accessary organs Inhibin Produced by sertoli cells Inhibits production of FSH 14. Hormone from Pineal gland Pineal gland-Third eye Located in the brain Transducer of photo stimulito hormone Melatonin Produced during dark hours Seasonality of reproduction Both on male & female More potent in female Long duration secretion =stimulatory Short duration = inhibitory 15. Summary of integration of organs & hormones to regulatereproduction15 16. www.lives-ethiopia.orgThe presentation has a Creative Commons licence. You are free to re-use or distribute this work, provided credit isgiven to ILRI.