Summary Neuroscience
Lecture 8: Neuroendocrine
Learning objectives
• You can explain how hydrophilic and hydrophobic hormones work.
• You can explain the HPA and SAM and thyroid neuroendocrine systems, and you can name
the brain areas and organs involved.
• You can explain what hormones mediate mating behaviour and you can explain the effects
of gonadal steroids on the brain.
The endocrine and nervous system
The central nervous system and the endocrine system have similar goals. The nervous
system collects information from your body on how things are going and sends out
information to change the physiology of the body. Hormones also monitor the homeostasis
in your body and try to regulate different functions of your body really in a system-wide
function. It again all depends on the target cell receptor.
Both systems specialise in long-distance communication of cells
,Hormones & Neuropeptides
Signalling molecules that bind to selective receptors.
Type of hormones:
- Water-soluble (hydrophilic) e.g., oxytocin (functions as neuropeptide and hormone)
• Amines: modified amino acids
• (Neuro)Peptides: short peptides
• Eicosanoids: derivatives of arachidonic acid
- Lipid-soluble (hydrophobic)
• Steroid hormones: derivatives of cholesterol
• Thyroid hormone: tyrosine conjugated with iodine (T3, T4)
Hydrophilic vs hydrophobic hormones: transport
• hydrophilic hormones are stored in vesicles, like neurotransmitters. They are secreted into
the bloodstream for transport to the target cell. (Resemble the dense core vesicles, also use
SNARE and sometimes respond to calcium)
• hydrophobic hormones are synthesized upon demand and released through diffusion, like
endocannabinoids. For long-range transport in the blood, their hydrophobic moieties are
shielded by a carrier protein. Association and dissociation (on/off) cause proper function.
The action of hydrophilic and hydrophobic hormones
,Q: what type of hormone would affect the CNS more and why? → Both hormones are very
important for the nervous system but the hydrophobic hormones have the most impact on
the nervous system. The reason is that the hydrophobic ones can cross the blood-brain
barrier relatively easily. (blood-brain barrier is to make sure hydrophilic compounds can’t
just enter the brain via astrocytes)
Can enter the brain:
Steroid hormones are derivatives of cholesterol e.g., progesterone, testoterol and estradiol
Another example is cortisol secreted by the adrenal gland. These hydrophobic hormones can
cross the blood-brain-barrier. This is often not the case for hydrophilic hormones.
The blood-brain barrier is a filter between the bloodstream and the central nervous system.
Steroid hormones affect brain function
, The endocrine system contains many feedback loops-→ help to maintain homeostasis
The pituitary is not always seen in anatomy preparation because when you make these
preparations the pituitary often stays behind because it is on the outside against the
meringues which keep it stuck against the skull.
Lecture 8: Neuroendocrine
Learning objectives
• You can explain how hydrophilic and hydrophobic hormones work.
• You can explain the HPA and SAM and thyroid neuroendocrine systems, and you can name
the brain areas and organs involved.
• You can explain what hormones mediate mating behaviour and you can explain the effects
of gonadal steroids on the brain.
The endocrine and nervous system
The central nervous system and the endocrine system have similar goals. The nervous
system collects information from your body on how things are going and sends out
information to change the physiology of the body. Hormones also monitor the homeostasis
in your body and try to regulate different functions of your body really in a system-wide
function. It again all depends on the target cell receptor.
Both systems specialise in long-distance communication of cells
,Hormones & Neuropeptides
Signalling molecules that bind to selective receptors.
Type of hormones:
- Water-soluble (hydrophilic) e.g., oxytocin (functions as neuropeptide and hormone)
• Amines: modified amino acids
• (Neuro)Peptides: short peptides
• Eicosanoids: derivatives of arachidonic acid
- Lipid-soluble (hydrophobic)
• Steroid hormones: derivatives of cholesterol
• Thyroid hormone: tyrosine conjugated with iodine (T3, T4)
Hydrophilic vs hydrophobic hormones: transport
• hydrophilic hormones are stored in vesicles, like neurotransmitters. They are secreted into
the bloodstream for transport to the target cell. (Resemble the dense core vesicles, also use
SNARE and sometimes respond to calcium)
• hydrophobic hormones are synthesized upon demand and released through diffusion, like
endocannabinoids. For long-range transport in the blood, their hydrophobic moieties are
shielded by a carrier protein. Association and dissociation (on/off) cause proper function.
The action of hydrophilic and hydrophobic hormones
,Q: what type of hormone would affect the CNS more and why? → Both hormones are very
important for the nervous system but the hydrophobic hormones have the most impact on
the nervous system. The reason is that the hydrophobic ones can cross the blood-brain
barrier relatively easily. (blood-brain barrier is to make sure hydrophilic compounds can’t
just enter the brain via astrocytes)
Can enter the brain:
Steroid hormones are derivatives of cholesterol e.g., progesterone, testoterol and estradiol
Another example is cortisol secreted by the adrenal gland. These hydrophobic hormones can
cross the blood-brain-barrier. This is often not the case for hydrophilic hormones.
The blood-brain barrier is a filter between the bloodstream and the central nervous system.
Steroid hormones affect brain function
, The endocrine system contains many feedback loops-→ help to maintain homeostasis
The pituitary is not always seen in anatomy preparation because when you make these
preparations the pituitary often stays behind because it is on the outside against the
meringues which keep it stuck against the skull.
