Hormones

2025-10-09

Rick Gilmore

Department of Psychology

Prelude

– Songs (2018)

Monoamine Song

Monoamines, do-do do do-do
Monoamines, do do do-do
Monoamines, do do do do-do do do-do do do-do do do do do-do do

Monoamine Song

Monoamines, do-pa-mine is one
Monoamines, nor-epi, too
Monoamines, sero-tonin e-pinephrine, dop-a-mine, nor-epinephrine, melatonin, whoo!

Monoamine Song

Monoamines, mod-u-late neurons
Monoamines, throughout the brain
Monoamines, keep people happy, brains snappy, not sleepy, not sappy, do-do do-do do-do do

Today’s topics

Wrap-up on neurochemistry
Hormones

Warm-up

Motor neurons in the PNS release this neurotransmitter onto skeletal muscles:

A. Glutamate
B. GABA
C. Dopamine
D. Acetylcholine (ACh)

Motor neurons in the PNS release this neurotransmitter onto skeletal muscles:

~~A. Glutamate~~
~~B. GABA~~
~~C. Dopamine~~
D. Acetylcholine (ACh)

What neurotransmitter is released widely across the CNS, at as many as 1/2 of all synapses?

A. Acetylcholine
B. Serotonin (5-HT)
C. Glutamate
D. Glycine

What neurotransmitter is released widely across the CNS, at as many as 1/2 of all synapses?

~~A. Acetylcholine~~
~~B. Serotonin (5-HT)~~
C. Glutamate
~~D. Glycine~~

Where in the brain are nuclei whose axons release dopamine (DA), norepinephrine (NE), and serotonin. (5-HT) found?

A. Cerebral cortex
B. Midbrain and hindbrain
C. Thalamus
D. Hypothalamus

Where in the brain are nuclei whose axons release dopamine (DA), norepinephrine (NE), and serotonin (5-HT) found?

~~A. Cerebral cortex~~
B. Midbrain and hindbrain
~~C. Thalamus~~
~~D. Hypothalamus~~

Norepinephrine (NE) projections from Locus Coeruleus

Neurochemistry wrap-up

Key points about monoamines

Monoamine neurotransmitters–DA, NE, 5-HT–modulate activity of other neurons
Monoamines are released from specific locations
- DA & NE from midbrain, 5-HT from hind brain
Monoamines project widely throughout the CNS

Key points about monoamines

Monoamines are inactivated chemically and via transporters
Many drugs that treat psychiatric illness affect monoamines
Most monoamines activate metabotropic receptors

Histamine

In forebrain, released by hypothalamus, projects to whole brain
- Metabotropic receptors
- Role in arousal/sleep regulation
- Anti-histamines can induce sleep
In body, part of immune response

Other NTs

Gases
- Nitric Oxide (NO), carbon monoxide (CO)
Neuropeptides
- Substance P and endorphins (endogenous morphine-like compounds) have role in pain
- Orexin/hypocretin, project from lateral hypothalamus across brain, regulate appetite, arousal

Other NTs

Neuropeptides (continued)
- Cholecystokinin (CCK) stimulates digestion
- Oxytocin and vasopressin released by posterior hypothalamus onto posterior pituitary, regulate social behavior

Why are there so many neurotransmitters?

Non-chemical communication between neurons

Gap junctions
Electrical coupling
Connect cytoplasm directly

Non-chemical communication between neurons

Fast, but fixed, hard to modulate
Examples: retina, cardiac muscle

Ways to think about synaptic communication

Specificity: point-to-point vs. broadcast
Timing of action: Direct (immediate, short-term) vs. (delayed, prolonged)
Are non-NT substances agonists or antagonists?

Agonists vs. Antagonists

Agonists
- bind to receptor
- mimic action of endogenous chemical
Antagonists
- bind to receptor
- block/impede action of endogenous chemical

Valium is a GABA-A receptor agonist. This means:

A. It decreases inhibition
B. It activates a metabotropic Cl- channel
C. It facilitates/increases Cl- flow
D. It blocks an ionotropic channel

Valium is a GABA-A receptor agonist. This means:

~~A. It decreases inhibition~~
~~B. It activates a metabotropic Cl- channel~~
C. It facilitates/increases Cl- flow
~~D. It blocks an ionotropic channel~~

Hormones

Hormones are…

Chemicals secreted into blood
Act on specific target tissues via receptors
Produce specific effects

Can a substance be a hormone AND a neurotransmitter?

A. No
B. Yes

Can a substance be a hormone AND a neurotransmitter?

~~A. No~~
B. Yes

If the substances:
- are released by neurons
- bind to neurons, and
- bind to other cells in the body.

Substances that are both hormones and neurotransmitters

Melatonin
Epinephrine/adrenaline
Oxytocin
Vasopressin

Physiological responses and behaviors under hormonal influence

Ingestive (eating/ drinking)
- Fluid levels
- Na, K, Ca levels
- Digestion
- Blood glucose levels

Physiological responses and behaviors under hormonal influence

Reproduction
- Sexual Maturation
- Mating
- Birth
- Care giving

Physiological responses and behaviors under hormonal influence

Responses to threat/challenge
- Metabolism
- Heart rate, blood pressure
- Digestion
- Arousal

Commonalities

Biological imperatives
Events restricted in space and time

Differences: Neural vs. hormonal communication

Point to point vs.“broadcast”
- Wider broadcast than neuromodulators
- Everywhere in body via bloodstream
Fast vs. slow-acting

Differences: Neural vs. hormonal communication

Short-acting vs. long-acting
Digital (yes-no) vs. analog (graded)
Voluntary control vs. involuntary

Similarities: Neural vs. hormonal communication

Chemical messengers stored for later release
Release follows stimulation
Action depends on specific receptors
2nd messenger (metabotropic receptors) systems common

Biology

Rest of body
- Thyroid
- Adrenal (ad=adjacent, renal=kidney) gland
  - Adrenal cortex
  - Adrenal medulla
- Gonads (testes/ovaries)

Biology

CNS
- Hypothalamus
- Pituitary
  - Anterior
  - Posterior
- Pineal gland

Two release systems

From hypothalamus/pituitary into bloodstream
- Direct
- Indirect

Direct release

Hypothalamus ->
Posterior pituitary
- Oxytocin
- Arginine Vasopressin (AVP, vasopressin), also known as anti-diurectic hormone (ADH)

Indirect release

Hypothalamus -> releasing hormones
Anterior pituitary -> tropic hormones

Indirect release

Blood stream ->
End organs

Case studies in neural & hormonal communication

Responses to threat or challenge

Neural response
- Sympathatic NS activation of heart, lungs, etc.
- Sympathetic Adrenal Medullary (SAM) axis (also system or response)
  - Releases NE and Epi into bloodstream

Responses to threat or challenge

Endocrine response
- Hypothalamic Pituitary Adrenal (HPA) axis
Hypothalamus
- Releases Corticotropin Releasing Hormone (CRH)
Anterior pituitary
- Releases Adrenocorticotropic hormone (ACTH)

Responses to threat or challenge

Adrenal cortex
- Responds to ACTH from anterior pituitary
- Releases Glucocorticoids (e.g., cortisol)

Responses to threat or challenge

Glucocorticoids (e.g., cortisol)
- increase blood glucose production
- reduce inflammation
- suppress immune system
- prolonged exposure unhealthy

Cortisol affects brain, too

Via receptors for CRF, cortisol

Reproductive behavior

https://mom.com/baby/15-resources-breastfeeding-moms

Reproductive behavior

Milk letdown reflex
Sensory inputs from infant (sight, smell, sound, touch)
Hypothalamus releases oxytocin into posterior pituitary
Oxytocin activates milk ducts in breast tissue

Oxytocin has multiple roles

Sexual arousal
Released in bursts during orgasm
Stimulates uterine, vaginal contraction
Links to social interaction, bonding: Weisman & Feldman (2013)
Alters face processing in autism: Domes et al. (2013)

Effects of “knocking-out” oxytocin receptors?

Ledford (2023)

Folk psychology memes

Oversimplify
Neurotransmitters and hormones have multiple physiological effects
Nervous system and rest of body connected, interact
Simplification sometimes useful, but can also mislead

Wrap-up

Main points

Hormones are chemicals secreted into the blood
Hormones bind to specialized receptors in the body and the nervous system
Hormones influence biologically critical behaviors and physiology
Hypothalamus controls hormone release via pituitary
Release is indirect (via anterior pituitary) or direct (via posterior pituitary)

Next time

Quiz 2
Evolution of the nervous system

Resources

About

This talk was produced using Quarto, using the RStudio Integrated Development Environment (IDE), version 2025.5.1.513.

The source files are in R and R Markdown, then rendered to HTML using the revealJS framework. The HTML slides are hosted in a GitHub repo and served by GitHub pages: https://psu-psychology.github.io/psych-260-2025-fall/

References

Deussing, J. M., & Chen, A. (2018). The Corticotropin-Releasing Factor family: Physiology of the stress response. Physiological Reviews, 98(4), 2225–2286. https://doi.org/10.1152/physrev.00042.2017

Domes, G., Heinrichs, M., Kumbier, E., Grossmann, A., Hauenstein, K., & Herpertz, S. C. (2013). Effects of intranasal oxytocin on the neural basis of face processing in autism spectrum disorder. Biological Psychiatry, 74(3), 164–171. https://doi.org/http://dx.doi.org/10.1016/j.biopsych.2013.02.007

Haas, H., & Panula, P. (2003). The role of histamine and the tuberomamillary nucleus in the nervous system. Nature Reviews. Neuroscience, 4(2), 121–130. https://doi.org/10.1038/nrn1034

Ledford, H. (2023, January 27). CRISPR voles can’t detect “love hormone” oxytocin — but still mate for life. https://doi.org/10.1038/d41586-023-00197-9

Sikich, L., Kolevzon, A., King, B. H., McDougle, C. J., Sanders, K. B., Kim, S.-J., … Veenstra-VanderWeele, J. (2021). Intranasal oxytocin in children and adolescents with autism spectrum disorder. The New England Journal of Medicine, 385, 1462–1473. https://doi.org/10.1056/NEJMoa2103583

Songs, M. (2018). Muppet songs: Mahna mahna (muppet show - 1976). Youtube. Retrieved from https://www.youtube.com/watch?v=TbZ_hTEOKZc

Weisman, O., & Feldman, R. (2013). Oxytocin effects on the human brain: Findings, questions, and future directions. Biological Psychiatry, 74(3), 158–159. https://doi.org/http://dx.doi.org/10.1016/j.biopsych.2013.05.026

Hormones

Prelude

Monoamine Song

Monoamine Song

Monoamine Song

Today’s topics

Warm-up

Motor neurons in the PNS release this neurotransmitter onto skeletal muscles:

Motor neurons in the PNS release this neurotransmitter onto skeletal muscles:

What neurotransmitter is released widely across the CNS, at as many as 1/2 of all synapses?

What neurotransmitter is released widely across the CNS, at as many as 1/2 of all synapses?

Where in the brain are nuclei whose axons release dopamine (DA), norepinephrine (NE), and serotonin. (5-HT) found?

Where in the brain are nuclei whose axons release dopamine (DA), norepinephrine (NE), and serotonin (5-HT) found?

Neurochemistry wrap-up

Key points about monoamines

Key points about monoamines

Histamine

Other NTs

Other NTs

Why are there so many neurotransmitters?

Non-chemical communication between neurons

Non-chemical communication between neurons

Ways to think about synaptic communication

Agonists vs. Antagonists

Valium is a GABA-A receptor agonist. This means:

Valium is a GABA-A receptor agonist. This means:

Hormones

Hormones are…

Can a substance be a hormone AND a neurotransmitter?

Can a substance be a hormone AND a neurotransmitter?

Substances that are both hormones and neurotransmitters

Physiological responses and behaviors under hormonal influence

Physiological responses and behaviors under hormonal influence

Physiological responses and behaviors under hormonal influence

Commonalities

Differences: Neural vs. hormonal communication

Differences: Neural vs. hormonal communication

Similarities: Neural vs. hormonal communication

Biology

Biology

Two release systems

Direct release

Indirect release

Indirect release

Case studies in neural & hormonal communication

Responses to threat or challenge

Responses to threat or challenge

Responses to threat or challenge

Responses to threat or challenge

Responses to threat or challenge

Cortisol affects brain, too

Reproductive behavior

Reproductive behavior

Oxytocin has multiple roles

But, can oxytocin treat social impairments in autism?

Effects of “knocking-out” oxytocin receptors?

Folk psychology memes

Folk psychology memes

Folk psychology memes

Folk psychology memes

Wrap-up

Main points

Next time

Resources

About

References