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Ryan Klimczak Discussion 7 April 16th, 2007 Lectures 27,28,29-32. Hypophysiotopic hormones ( A hormone secreted by the hypothalamus that stimulates or inhibits the adenohypophysis portion of the pituitary gland)
April 16th, 2007
(A hormone secreted by the hypothalamus that stimulates or inhibits the adenohypophysis portion of the pituitary gland)
CRH - corticotropic releasing hormone - released from the hypothalamus. It interacts with the pituitary to produce adrenocorticotropin hormone. Involved in the stress response.
GHRH - growth hormone releasing hormone - The hormone released from the hypothalamus that causes the release of growth hormone from the pituitary gland
GHIH - growth hormone inhibitory hormone - (somatostatin) - inhibits the release of GH and TSH, suppresses the release of gastrointestinal and pancreatic hormones and also suppressed the exocrine secretory function of the pancrease
PRH - prolactin releasing hormone - A polypeptidehormone that originates in the hypothalamus and stimulates the secretion of prolactin in the pituitary gland.
GnRH - gonadotropin releasing hormone - A hormone made by the hypothalamus (part of the brain). GnRH causes the pituitary gland to make luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones are involved in reproduction
TRH - thyrotopin-releasing hormone - hormone released by the hypothalamus that controls the release of thyroid-stimulating hormone from the anterior pituitary
ACTH - adrenocorticotropin hormone - Hormone produced by the pituitary gland, which stimulates the adrenal glands to produce cortisone
LH - lutenizing hormone - A pituitary hormone that stimulates the gonads. In the man LH is necessary for spermatogenesis (Sertoli cell function) and for the production of testosterone (Leydig cell function). In the woman LH is necessary for the production of estrogen. When oestrogen reaches a critical peak, the pituitary releases a surge of LH (the LH spike), which releases the egg from the follicle. [Gonadotropin]
FSH - follicle stimulating hormone - hormone secreted by the pituitary gland in the brain that stimulates the growth and maturation of eggs in females and sperm in males, and sex hormone production in both males and females. [Gonadotropin]
Vasopressin: hormone secreted by the posterior pituitary gland and also by nerve endings in the hypothalamus; affects blood pressure by stimulating capillary muscles and reduces urine flow by affecting reabsorption of water by kidney tubules
Oxytocin: involved in reproductive behaviour in both men and women, and apparently triggers "caring" behavior. It is also the hormone which allows contractions of the womb during pregnancy and labour
PL - prolactin - hormone produced by the pituitary gland that stimulates breast development and milk production.
TSH - thyroid stimulating hormone - Ahormone secreted by the anterior pituitary gland, that controls the production and release of the thyroid hormones (T4 and T3)
GH - growth hormone - A peptide hormone, made in the anterior pituitary, that stimulates tissue and skeletal growth
MSH - melanocyte stimulating hormone - stimulates the production and release of melanin (melanogenesis) by melanocytes in skin and hair. MSH is also produced by a subpopulation of neurons in the arcuate nucleus of the hypothalamus. MSH released into the brain by these neurons has effects on appetite and sexual arousal.
Cortisol - One of the primary catabolic hormones in the body. It is typically secreted in response to physical trauma or prolonged stress. Its functions include controlling inflammation, increasing muscular catabolism and glycolysis, suppressing immune response, and maintaining normal vascular circulation and renal function, among others.
Epinephrine (Adrenaline) - A hormone produced by the adrenal glands that also acts as a neurotransmitter for nerve cells. As part of the fight-or-flight response, epinephrine signals the heart to pump harder, increases blood pressure and has other effects on the cardiovascular system. It helps the liver release glucose (sugar) and limits the release of insulin.
Norepinephrine (Noradrenaline) - A neurotransmitter and a hormone. It is released by the sympathetic nervous system onto the heart, blood vessels, and other organs, and by the adrenal gland into the bloodstream as part of the fight-or-flight response. Norepinephrine in the brain is used as a neurotransmitter in normal brain processes.
DHEA - (dehydroepiandrosterone) steroid precursor produced by the adrenal gland and converted to testosterone or the estrogens by the body's tissues. Adequate DHEA levels give the body the building blocks necessary to produce these hormones.
Thyroxine: The thyroid hormones, thyroxine (T4) and triiodothyronine (T3), are tyrosine-based hormones produced by the thyroid gland. They act on the body to increase the basal metabolic rate, affect protein synthesis and increase the body's sensitivity to catecholamines (such as adrenaline). An important component in the synthesis is iodine.
Testosterone - the male sex hormone, secreted by the testes but also synthesised in small quantities in the adrenal glands. Testosterone is necessary in the foetus for the development of male genitalia, and increased levels of testosterone at puberty result in the further growth of genitalia and the development of male secondary sex characteristics such as facial hair.
DHT - Dihydrotestosterone - The enzyme 5 alpha reductase converts testosterone into its more potent form DHT. considered to be an aging-bio-marker. Among its affects are the appearance of body-hair, the loss of scalp hair and the onset of prostate gland problems.
Estrogen - The female sex hormone produced by the ovary. Estrogens are responsible for the development of secondary sexual characteristics and cyclic changes in the viginal epithelium and endothelium of the uterus.
Progesterone: A female hormone secreted by the corpus luteum after ovulation during the second half of the menstrual cycle (luteal phase). It prepares the lining of the uterus (endometrium) for implantation of a fertilized egg and allows for complete shedding of the endometrium at the time of menstruation. In the event of pregnancy, the progesterone level remains stable beginning a week or so after conception.
Inhibin: Peptide that is an inhibitor of FSH synthesis and secretion and participates in the regulation of the menstrual cycle.
Metabolic rate, body composition, dietary regimen, physical exercise, exposure to stress (environmental and psychosocial)
Relations with other endocrines and body systems
Secretory cells and their rates of secretion
Transport of the hormones to target cells
Number and affinity of hormone receptors
Intracellular postreceptor molecular events
Occurrence of disease and use of medications
No significant changes in healthy, non-stressed, elderly
The few changes that occur are rapidly compensated for (e.g. decreased secretion of GCs from the adrenal cortex)
less rapid metabolism in the liver & less urine excretion
Therefore the circulating levels remain constant
Also, normal ACTH & cortisol responses to CRH administration
Some alterations of the circadian rhythm
From Greek: homeo “the same” stasis “state”
Indicates that for optimal function of the organism, a steady state (or equilibrium) must be achieved
This “constancy” of the internal environment allows survival despite continuing changes in the external environment (stress)
A constant environment obtained through a series of dynamic adjustments
This continual need for adjustment is implicated in the term “allostasis”
(From Greek allo “different” stasis “state”)
Emphasizes the dynamism of adaptive responses to stress
This adaptation to stress is often achieved with a price -- a declining ability to adapt and/or an increased pathology and disease
*Prof. T. Seeman, Geriatrics, UCLA (UCB alumna)
Resistance/ adaptation to stress
Several lines of investigations have shown that manipulation of the genome will result in changes of the phenome. These changes involve alteration of the endocrine signaling with a shift
Suppressing signaling from hormones such as: insulin, growth hormone, insulin-like growth hormone and others
constructing mutants with lack of the hormone or the hormone receptors
can prolong the lifespan
as much as six times the lifespan in C. Elegans,delaying the aging process
“I cannot, and should not, be cured of my stress but merely taught to enjoy it” Hans Selye, l950
Responses to stress are indispensable to our survival as they allow us to maintain the internal equilibrium necessary for optimal function
Responses to stress are multifactorial (depend on interactions of several systems)
If response to stress is severe & prolonged it may represent a major risk for the “diseases of adaptation”
(e.g. cardiovascular, cognitive, emotional, metabolic diseases)
& shorten the lifespan
LONGEVITY is associated
With stimulation (up-regulation)
Of genes involved in response to stress including those of HSP
HSPs act as chaperones and
promote greater tolerance/resistance
to stress (thermic and others)
Hence, increased longevity and hormesis may depend on
Increased HSPs and their actions as chaperones
Major actions of insulin
Glucose transport into
muscle & adipose cells
overall body growth (general effect)
intracellular transport of amino acids & lipids & protein and triglyceride synthesis
glycogen synthesis in liver and muscle cells
gluconeogenesis (in liver)
uptake (in muscle)
Endogenous production of glucose
Storage of glucose
(in liver as glycogen), fat & amino
Acids arriving in the blood form
Utilization of glucose
(muscle & adipose cells)
Glucose from blood vessel
Insulin primarily targets muscle cells / adipocytes
glucose uptake Hyperglycemia
protein catabolism plasma amino acid
Weight loss, growth inhibition
Negative nitrogen balance
lipolysys free fatty acids
Vascular changes Microangiopathies
Primary sex organ suspended outside of the body in
Secondary male sex organs include:
which carry sperm to the urethra
SEMINAL VESISCLES, PROSTATE, & BULBOURETHRAL GLANDS
which secrete seminal fluid
PENIS with URETHRA
through which flow both urine and semen
The hypothalamus releases GnRH into the circulatory system and, through blood, directly into the pituitary.
GnRH triggers the release of the pituitary LH and FSH that stimulate the testes to testosterone secretion and sperm production.
organ, contains three types of cells, all
necessary for reproduction:
the GERM CELLS or GAMETES,
involved in fertilization.
the INTERSTITIAL CELLS of LEYDIG
that secrete testosterone, the major androgen
the SERTOLI CELLSwith secretory and reproductive functions
Sensitivity of androgen secretion to LH
Sensitivity of negative feedback between GnRH and LH
Overall health status
Size of the prostate
State of disease
**PSA controversary pp. 353, 354**
Change to pulsatile pattern: hDuration, iFrequency
“Monotropic FSH h
1st Noticed prior to any change in cycle length
Ovarian Steroidal Hormones
Estrone levels h early in the cycle in older ovulatory women
Possible due to LH/FSH alterations
Eventually, H-P-G axis is unable to generate LH surge needed for ovulationHormonal Changes From Aging
Change in microtubule and chromosome placement at the second metaphase of meiosis
May be linked to increased aneuploidy seen in offspring of older women
Declining Follicular Reserve
2 Million Primordial Follicles during fetal development
Declines to 1 million at birth and 250,000 by puberty
Primordial Follicles develop to primary and secondary follicles independent of hormone status
In the absence of LH/FSH, follicles undergo atresia
Once follicles are depleted, ovarian hormone production declinesOvarian Structural Changes