Lecture 18: Neuroendocrinology – Hormones to Brain Flashcards
What does it mean that the neuroendocrine relationships is reciprocal?
nervous system controls release of many different hormones, but many hormones also act on and influence activity of different neurons within the nervous system
ie. glucocorticoid hormones (ie. cortisol) can affect dendritic properties in hippocampus
What can gonadal steroid hormones powerfully modulate?
synaptic transmission and plasticity
How do hormones differ?
in their biochemical properties – including lipid solubility
What are the 3 biochemical classes of hormones?
- steroids
- peptides
- biogenic amines
What are steroids synthesized by?
modifications to cholesterol
What are peptides synthesized as?
gene products 3 to ~100 aa long
How are biogenic amines synthesized?
variable (but often derived from amino acids)
What is the solubility of steroids in lipids?
lipid soluble (diffuse through cell membranes)
What is the solubility of peptides in lipids?
not lipid soluble (must be transported around or across cell membranes)
What is the solubility of biogenic amines in lipids?
variable (depends on the hormone)
What are some examples of steroids?
testosterone, estrogen, cortisol
What are some examples of peptides?
oxytocin, CRH, leptin
What are some examples of biogenic amines?
epinephrine, melatonin, thyroxine
Which hormone classes can have retrograde neuroendocrine effects?
steroid and peptide hormones – both can influence behaviour by exerting actions within the CNS
Where is cortisol/corticosterone (steroid) released from?
What do these hormones affect?
released from adrenal cortex
affects stress, survival responses, memory
What is estrogen/testosterone/progesterone (steroid) derived from?
What do these hormones affect?
derived from gonads
affects reproductive and parental behaviour, aggression, (and memory)
Where is oxytocin/vasopressin (peptide) released from?
What do these hormones affect?
released from posterior pituitary gland
affects anxiety, aggression, social and parental behaviour
Where is leptin/ghrelin/CCK (peptide) released from?
What do these hormones affect?
released from adipocytes or various digestive tract organs
affect hunger, feeding, and satiety
What are the chemical properties of hormones that affect their ability to cross the BBB?
whether they are hydrophobic (lipid soluble) or hydrophilic (non-lipid soluble)
Can hydrophobic (lipid soluble) hormones cross the BBB?
can diffuse through membranes of endothelial cells, and therefore easily enter and interact with CNS – ie. steroids
Can hydrophilic (non-lipid soluble) hormones cross the BBB?
cannot diffuse through cell membranes, and cannot pass tight junctions that seal brain endothelial cells (BBB) – ie. peptides