Reproductive Endocrinology
Animal
Breeding
Pensacola
Jr College
Endocrinology
w Endocrine
Glands = ductless glands that secrete hormones directly into the bloodstream
w Hormone
= molecule carried by blood to target organ, binds to receptors, regulates an
activity
Hormone Types
w Protein
hormones
Large
Have cell surface receptors
Break down if given orally
w Steroid
hormones
Small
Have internal cell receptors
Absorbed if given orally
Endocrine Control
w Negative
feedback = hormone exerts negative control over earlier steps in chain
w Positive
feedback = hormone exerts positive control over earlier steps in chain
Example of Feedback Theory
Endocrine Reproductive Glands
Endocrine Reproductive Hormones
Female Repro Hormones
w GnRH
made in nerve cell bodies in hypothalamus ΰ
portal vessels ΰ
carried to anterior pituitary
w Stimulates LH and FSH production in ant.
pituitary ΰ
carried to ovaries
Female (contd)
w LH
in ovaries:
Causes ovulation
Stimulates CL formation
Stimulates luteal cells to produce progesterone
w FSH
in ovaries:
Makes follicles grow
Stimulates granulosa cells to produce estrogen, inhibin
Female hormone feedback
w Progesterone
has negative feedback on LH, FSH, GnRH
w Inhibin
has negative feedback on FSH
w Estrogen
small
doses have negative feedback on LH, FSH, GnRH
Large dose positive feedback
Female repro steroids
w Estrogen
= the cycle / preparation hormone
Female development
Cyclical changes in the
reproductive tract, estrus cycle
Mating behavior
Mammary tissue growth (ducts)
Female repro steroids
w Progesterone
= hormone of pregnancy
Inhibits mating behavior
Maintenance of pregnancy
(uterine endometrial growth, stops cycling)
Mammary tissue growth
(glandular)
Male Repro Hormones
w GnRH
made in nerve cell bodies in hypothalamus ΰ
portal vessels ΰ
carried to anterior pituitary
w Stimulates LH and FSH production in ant.
pituitary ΰ
carried to testes
Male (contd)
w LH
in testes:
Receptor sites on leydig cells
Stimulates testosterone
production
w FSH
in testes:
Receptor sites on sertoli cells
Stimulates ABP (binds T) and inhibin production
Stimulates sperm formation
Male hormone feedback
w Testosterone
has negative feedback on LH, FSH, GnRH
w Inhibin
has negative feedback on FSH
Male repro steroid
w Testosterone
Development
and maintenance of all the male ducts, glands, etc.
Spermatogenesis
Seminal fluid production
Male sexual behavior
Prolactin
in Reproduction
w Produced
by anterior pituitary
w Controls
milk production
w Controls
reproduction in many seasonal breeders
Increases LH receptor sites
on CL ΰ
increases progesterone
Thus, low prolactin
delays implantation
Control of Prolactin
w Pineal
gland produces the hormone melatonin at high levels during darkness
w Lots
of melatonin during short daylength (fall/winter)
w Melatonin
inhibits prolactin
w Increasing
daylengths thus allow increased prolactin
Oxytocin
in Reproduction
w Produced
by hypothalamus cell bodies
w Carried
on nerve fibers to posterior pituitary for storage
w Functions:
Contractions of uterus in
birth
Milk ejections in lactation
w Positive
feedback loop from nerve stimulation
Example Hormone Research in Zoos:
w Urinary Steroid Hormone Analysis of
Ovarian Cycles and Pregnancy in Mandrills (Mandrillus sphinx) Indicate That Menses, Copulatory
Behavior, Sexual Swellings and Reproductive Condition Are Associated With
Changing Estrone Conjugates (E1C) and
Pregnanediol-3-Glucuronide (PdG)
w Disneys Animal Kingdom