Antibodies against insulin hormone have been observed
in many conditions. These can be against endogenous or
exogenous insulin. It is found in Type 1 diabetes. These are
developed under insulin therapy. There are two types of
Antibodies against insulin, produced in the body (human
Antibodies against insulin, taken by medication—insulin
injection (bovine, porcine and recombinant human
Both types are present in the body. Detection of both
Glucagon is a small protein produced by alpha cells
within the islets that cause the level of blood glucose
to increase. Its release is controlled by blood levels of
glucose. As levels fall, glucagon release is increased
causing the release of stored glucose and the synthesis of
glucose until levels are increased and glucagon release is
then reduced via negative feedback. Glucagon opposes
the metabolic actions of insulin. This opposition plus the
negative feedback control of glucose levels maintain very
tight control on blood glucose levels.
Testosterone is the principal hormone of the testes and
is synthesized from cholesterol by the Leydig cells. The
secretion of testosterone is under the control of LH from
the pituitary. The LH secretion is decreased by increased
levels of testosterone in the blood via negative feedback.
Testosterone develops and maintains the male secondary
sex characteristics, is anabolic and growth promoting
and participates in the formation of sperm. It also causes
aggressive behavior and increased libido. Body hair is
increased by androgens while scalp hair is decreased.
Like other steroids, testosterone enters cells and binds
to an intracellular receptor and then causes the production
of mRNA coding for proteins that manifest the changes
induced by testosterone. In some target tissues a form of
testosterone, DHT, is produced that has greater stability in
combination with the receptor and, therefore, produces a
longer lasting effect. The DHT is needed for the maturation
development of the internal genitalia and maintenance of
the male libido and sex drive.
Another hormone produced by the testes is the
polypeptide hormone, inhibin, produced by the Sertoli
cells. It inhibits FSH secretion by a direct action on the
¾ Improper growth—eunuchoid features
The ovaries produce the steroid hormones (estrogens and
progesterone) that cause the development of secondary
sexual characteristics and develop and maintain the
reproductive function in the female. Specifically, the
estrogens are secreted by the theca interna cells and the
granulosa cells of the ovarian follicle, the corpus luteum
and the placenta. The LH from the anterior pituitary binds
to receptors on theca interna or granulosa cells to cause the
production of estradiol from cholesterol or a downstream
precursor androstenedione that is passed from the thecal
cells to the granulosa cells. Progesterone is secreted mostly
by the corpus luteum and the placenta, but some are
made by the developing follicle. Negative feedback from
progesterone decreases LH secretion and large doses can
Estradiol is the most potent and major secreted estrogen
although estrone and estriol can be found in circulation as
well. Like other steroid hormones, estrogens enter target
cells, combine with a nuclear receptor and cause the
production of mRNAs that, when translated into proteins,
modify cell function. Estrogens are metabolized by the
liver and secreted in bile where some are reabsorbed back
into the body. Metabolites of estradiol are excreted in the
Estrogens in the bloodstream inhibit the release of FSH
and LH, in some circumstances, via negative feedback. At
other times, as in the preovulatory LH surge, estrogens
increase the release of LH, via positive feedback. Estrogen
also increases the excitability of uterine smooth muscle,
myometrial sensitivity to oxytocin and increases the libido
in women by a direct action on hypothalamic neurons.
Estrogens lower plasma cholesterol, inhibit
atherogenesis (plaque formation in blood vessels), and
are protective against myocardial infarction as suggested
by the lower incidence of heart attacks and atherosclerosis
Pregnant women: Placenta (mainly estriol—E3)
Nonpregnant women: Ovaries (mainly estradiol—E2).
Progesterone has the principal targets of the uterus,
breasts and the brain. It promotes the development of
breast tissue, causes changes in the endometrial lining
during the luteal phase of the cycle, decreases the
excitability of myometrial cells and decreases uterine
¾ Congenital adrenal hyperplasia
The pineal gland can be found deep in the brain at the top
of the third ventricle where it is in close communication
with the cerebrospinal fluid. In the adult, the pineal
gland can often be seen in X-rays of the brain because
of the accumulation of radiopaque calcium phosphate
and carbonate into small granules called pineal sand. The
cells of the pineal gland secrete the hormone Melatonin
in a diurnal cycle (the amount changes throughout a 24
hours period) where the amount remains low during the
daylight hours but increases during the dark hours. This
diurnal variation is controlled by norepinephrine from
sympathetic nervous input that is regulated by the lightdark cycle in the environment.
Although some people use melatonin supplements to
treat insomnia, this effect has not been proven in scientific
trials. There have been reports of increased insomnia and
depression as well as other side effects associated with its
Disturbance in the hormonal system is a major cause of
male and female fertility problems.
The brain plays a key role in regulating the hormones
that affect the development of sperm (spermatogenesis)
in males and regulation of menstrual cycle (ovulation)
in females. The process begins when the hypothalamus
gland, located at the base of the brain. The pituitary
(follicle-stimulating hormone). These stimulate testicular
development and sperm production in males and regulate
the menstrual cycle and release of ovum in females.
The LH and FSH also regulate the production of
steroid hormones responsible for male and female sexual
The Four Factors of Male Fertility
Pretesticular Function (Hormones)
Disturbances in the hormonal system cause about 10% of
Testicular failure represents about 55% of male fertility
To respond to hormone stimulation properly, the
testicles, or testes, must be capable of producing sperm
Tubal obstruction including vasectomy accounts for about
The post-testicular system of ducts must be capable
of storing and delivering sperm. Sperm delivery system
problems include obstruction or interruption of the tubes
as a result of congenital malformation, disease, surgery, or
Ejaculatory Disturbance, Impotence, and
Ejaculatory disturbances, impotence, and sexual problems
may prevent the delivery of sperm.
These disorders represent about 10% of male fertility
Problems associated with male infertility
The Hypothalamus and Pituitary
Approximately every 90 minutes a specialized area in the
located at the base of the brain, to produce LH (luteinizing
hormone) and FSH (follicle-stimulating hormone). The LH
tells the testes to secrete the male hormone testosterone.
Testosterone stimulates the sexual desires and develops
and maintains male secondary sex characteristics such
as hair growth and deep voice. Together, testosterone and
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