Lecture 3 Flashcards
What question does in situ hybridization answer?
Where is the hormone being produced and in what quantity
What are the steps from the leptin case study?
- Clone gene, make purified Leptin
- Run a replacement study (ob/ob vs ob/ob +leptin)
- Produce antibodies to leptin; develop an assay (RIA, ELISA) to measure leptin concentrations in other species
- Immunocytochemical localization techniques: leptin is present in white and brown adipose tissue
- Determine where leptin acts in the brain
- Take tissue with leptin, search for leptin receptor. Clone receptor, use in situ hybridization to localize mRNA for leptin receptor (hypothalamus)
- Use gene replacement therapy to swap out ob gene for w/t gene. In mice, obesity and sterility were reversed
- Run genetic screen in humans
- Clinical translation studies: leptin replacement studies in humans are equivocal
How do you determine where leptin acts in the brain?
Label leptin with a radioactive tag and inject it into mice
Autoradiography showed binding sites of leptin (choroid plexus)
What is intracrine mediation?
Intracrine substances regulate intracellular events
What is autocrine mediation?
Autocrine substances feed back to influence the same cells that secreted them
What is paracrine mediation?
Paracrine cells secrete chemicals that affect adjacent cells
What is endocrine mediation?
Endocrine cells secrete chemicals into the bloodstream where they may travel to distant target cells
What is ectocrine mediation?
Ectocrine substances, such as pheromones are released into the environment by individuals to communicate with them
What are the 5 systems of chemical mediation and communication?
Intracrine mediation Autocrine mediation Paracrine mediation Endocrine mediation Ectocrine mediation
Chemical messenger
Any substance that is produced by a cell that affects the function of another cell
Cytokine
A chemical messenger that evokes proliferation of other cells, especially in the immune system
Hormone
A chemical messenger that is released into the bloodstream or tissue fluid system that affects the function of target cells some distance from the source
Neurohormone
A hormone produced by neurons
Neuromodulator
A hormone that changes (modulates) the response of a neuron o some other factors
Neuropeptide
A peptide hormone produced by a neuron
Neurosteroid
A steroid hormone produced by a neuron
Neurotransmitter
A chemical messenger that acts across the neural synapse
What is between the hypothalamus and pituitary? (2)
Median eminence and infundibulum stalk
Where is the hypothalamus located and where does it communicate?
The base of the brain and communicates with the pituitary via blood and neurons (axons)
What do the hypothalamus and pituitary do?
Serve to regulate many peripheral endocrine glands
PVN
Paraventricular nucleus
Where do hypothalamic axons project?
To the portal system which carries releasing factors to the anterior pituitary
What does the anterior pituitary do in response to the releasing factors?
Release their own tropic hormones into general circulation
What does the hypothalamus produce?
Releasing factors
What does the anterior pituitary produce?
Tropic hormones
What do peripheral glands release?
Hormones that have metabolic effects
What do peripheral hormones tend to provide?
Negative feedback to both the hypothalamus and anterior pituitary
What are the peripheral glands affected by the anterior pituitary?
Adrenals
Gonads
Thyroids
What are the tissues affected by peripheral hormones?
Muscles
Skin
Bones
Etc
What do hypothalamic axons do in terms of the posterior pituitary?
Hypothalamic neurons project axons to the posterior pituitary and those axon terminals release hormones into blood
What two things does the posterior pituitary receive from the hypothalamus?
Vasopressin (AVP and ADH) and oxytocin
What are the 5 hormones the hypothalamus releases to the anterior pituitary?
GnRH CRH TRH PRH GHRH
What does the HPG axis regulate? What are the hormones?
Regulates sexual development and behavior
GnRH
LH & FSH
Sex hormones
What does the HPA axis regulate? What are the hormones?
Regulates the stress response
CRH
ACTH
Glucocorticoids
What does the HP axis for thyroid regulate? What hormones?
Helps regulate energy metabolism
TH
TSH
T3 & T4
What does vasopressin do?
Regulates:
Water and sodium balance
Blood pressure, etc
Also activated in a stress response
What is oxytocin?
Hormone related to social behavior
Bonding, trust, relationships
