L1 Intro to Endocrine Pharmacology Flashcards
3 classes of hormones
- Peptide/protein hormones
- Steroid hormones
- Amino acid-based hormones
Briefly describe how the endocrine system works
- uses chemical messengers (hormones) to coordinate many aspects of physiology
- releases hormones into bloodstream where they’re transported to every cell in the body
- hormones will only affect cells that have receptors specific to that hormone
- hormones can affect many different cells and tissues at once
Can a cell contain receptors for many different hormones?
Yes
4 types of hormone receptors
- Ligand-gated ion channels (ionotropic receptors)
- G-protein coupled receptors (GPCRs)
- Kinase-linked receptors
- Nuclear receptors
Why do both kinase-linked receptors and nuclear receptors take longer to initiate a response after hormone binding?
Because they are dependent upon transcription and protein synthesis
Which hormone receptors are most commonly involved in hormone/receptor binding?
Kinase-linked receptors
Where can hormone receptors be located?
cell membrane, cytosol, nucleus
Peptide/protein hormones are secreted by?
- anterior and posterior pituitary gland
- pancreas
- parathyroid gland
Synthesis of peptide/protein hormones
- synthesised on rough ER, first as large proteins (preprohormones) which are cleaved to form prohormones in ER
- prohormones transferred to Golgi apparatus for packaging in secretory vesicles, then cleaved to form active hormones
- stored in secretory vesicle until needed
Why can’t peptide/protein hormones get across the cell membrane to bind nuclear receptors?
because they are water soluble
Steroid hormones are secreted by?
- adrenal cortex
- ovaries
- testes
- placenta
Most steroid hormones are synthesised from?
cholesterol
Structure of steroid hormones
consist of 3 cyclohexyl rings and one cyclopentyl ring combined in a single structure
Are steroid hormones stored?
No, they are synthesised as needed
Steroid hormones are __ soluble.
lipid
Steroid hormones circulate in the blood mainly bound to __.
plasma proteins
(only ~10% exist free in plasma)
What do protein-bound steroid hormones act as?
Act as a store to replenish free hormones (since they cannot readily cross lipid membranes)
Amino hormones are secreted by?
- thyroid
- adrenal medullae
Amino hormones are derived from __.
tyrosine
Amino acids are formed by?
the action of enzymes in the cytoplasmic compartment of glandular cells
Where are thyroid hormones stored?
in macromolecules of the protein thyroglobulin
Where are adrenal medullary amino hormones stored?
in secretory vesicles until needed
Hormone receptors mediate cellular changes after binding via regulation of…
- ion channels
- regulatory proteins
- enzymes
- gene activation
Melatonin released from pineal gland binds to which type of receptor?
GPCR
CRH released from hypothalamus binds to which type of receptor?
GPCR
GH released from pituitary gland binds to which type of receptor?
Kinase-linked receptor
ACTH released from pituitary gland binds to which type of receptor?
GPCR
Triiodothyronine released from thyroid gland binds to which type of receptor?
Nuclear receptor
PTH released from parathyroid gland binds to which type of receptor?
GPCR
Corticoids and adrenaline released from adrenal gland bind which type of receptors?
Nuclear receptor and GPCR, respectively
The pancreas secretes insulin and glucagon. To which receptor types do these hormones bind?
Kinase-linked receptor and GPCR, respectively
To which receptor type do oestrogen, progesterone and testosterone bind?
nuclear receptor
3 mechanisms of endocrine disease
- Hormone deficiency
- insufficient stimulation from pituitary
- hypofunction of gland itself
- increased clearance of hormones - Hormone excess
- excessive stimulation from pituitary
- hyperplasia or neoplasia of the gland
- ectopic hormone production (cancers) - Hormone resistance
Example of a drug that blocks adrenaline?
beta blocker e.g. atenolol
Example of a hormone (and neurotransmitter) that binds a ligand-gated ion channel?
Serotonin (5HT3 receptor)
