hormones and behavior

HORMONES AND BEHAVIOR
BEHA
AVIOR
• What animals do
– Mating
– Feeding
– Communicating
– Escaping predators
– Migration and dispersal
HORM
MONES
• Biological signal molecu
ules
– Secreted into blood
– Carried to target tissues
– Affect diverse processess
•
•
•
•
Growth
Development
Physiology
Behavior
HORMONES and
a BEHAVIOR
• Also known as “behavio
behavio
oral endocrinology”
endocrinology
– Integrative field
• Effects of hormones on behavior
• Effects of behavior on horrmones
• Importance
p
of mechanism
ms in evolution
– Regulation of life history va
ariation
HISTORICA
AL ROOTS
• Castration of domestica
ated animals for at least
2000 years
– Produces capons,
capons steerss,
s geldings,
geldings etc
– Removes primary source
e of testosterone
– Affects quality as food
– Affects behavior
• More manageable
• Less disruptive socially (le
ess interested in sex, fighting)
HISTORICA
AL ROOTS
• Castration of humans
– Castrati and Eunuchs: Prepubertal
P
castration
• Castrati: Castration intend
ded to retain singing voice
• Eunuchs: Castration inten
nded to eliminate sex drive
– Employed as guards for women (including harems)
– Timing of castration impo
ortant
BERTHOLD S EXPERIMENT
BERTHOLD’S
• 1849: A. A. Berthold
performed first formal
gy
endocrinology
experiment
• Demonstrated nonneural contribution by
the testes required for
normall d
development
l
t
of a rooster
BERTHOLD’S EXPERIMENT
CONCLU
USIONS
• Transplanted testes fully functional
• Birds with transplanted testes entirely normal
– Normal
N
l appearance
• Combs, wattles, plumage
e
– Normal behavior
• Normal vocalizing
• Normal aggression
• Normal mating
BERTHOLD’S EXPERIMENT
CONCLU
USIONS
• Hypothesized secretoryy product carried by blood
to target tissues
– Learned later to be testo
osterone
HORM
MONES
• Organic molecules prod
duced and released into
blood by endocrine (duc
ctless) glands and
tissues
• Carried by blood to targ
get tissues
• One
O or more examples
l produced
d
db
by virtually
i t ll allll
tissues
HORM
MONES
• Generally play dual role
es coordinating behavior
and physiology
– Example: Same hormones regulate gamete
maturation and mating behavior
b
• Mature gametes available
e when animals most actively
engaging in reproductive behavior
– (Some exceptions)
HORMO
ONES vs
NEUROTRAN
NSMITTERS
HORMONE S
SPECIFICITY
• Specific hormones only affect certain cells
• Hormones affect differe
ent cells in different ways
– Target
T
t cells
ll possess recceptors
t
f specific
for
ifi h
hormones
– Target cells vary in the transduction machinery they
possess
– Diverse responses to pa
articular hormones possible
TINBERGEN’S “4
“ QUESTIONS”
ABOUT BEHAVIOR
•
•
•
•
How does it develop?
What mechanisms caus
se it?
H
How
did it evolve?
l ?
How does it contribute to
t
survival?
Niko
Tinbergen
LEVELS OF
F ANALYSIS
• PROXIMATE CAUSES
– Developmental mechaniisms
• Genetic determinants of b
behavior
• Environmental determinants of behavior
– Immediate causal mecha
anisms
• Systems for detection of environmental
e
stimuli
• Systems
y
for integrating
g
g an
nd adjusting
j
g responsivenes
p
to
stimuli
• Systems for carrying out responses
r
LEVELS OF
F ANALYSIS
• ULTIMATE CAUSES
– Historical pathways lead
ding to behavioral trait
• Evolutionary stages
stages, from
m origin of trait to present
– Effects of selection on history of trait
• Effects of past and curren
nt usefulness on survival and
reproductive success
– Both natural and sexual se
election important
HORMONE – BEHAVIOR
INTERAC
CTIONS
HORMONE – BEHAVIOR
INTERAC
CTIONS
• Proximate
– Hormones affect develop
pment and expression of
behavior
• Do not cause behavior themselves
• Affect frequency
q
y and inten
nsityy of expression
p
• Organizational / activation
nal effects
HORMONE – BEHAVIOR
INTERAC
CTIONS
• Ultimate
– Mechanistic control of be
ehavior affects fitness
– Mechanisms shared by rrelated taxa
– Affects evolution of both behavior and mechanisms
underlying development and expression of it
Overview of the Endocrine System
m
I. The endocrine system: general considera
ations
Definitions
Classes of hormones
V t b t endocrine
Vertebrate
d
i glands
l d
VI Gonads
VI.
G
d Male&
M l & Female
F
l
Androgens
II. Hypothalamus/pituitary
Progesterone
Anatomy
y
Estrogens
g
Anterior pituitary hormones
Posterior pituitary hormones
VII. Digestive system
Hypothalamic releasing hormones
Pancreas
Stomach/small intestine
III. Pineal gland
Melatonin
VIII. Mechanisms of hormone action
General considerations
IV. Thyroid gland
Hydrophilic hormones
Thyroid hormone
(Peptides/amines)
Lipophilic Hormones
V Adrenal gland
V.
(Steroid hormones/
Catecholamines
thyroid hormones)
Adrenal steroids
WHAT EXACTLY ARE
A
HORMONES?
• Organic molecules produced an
nd released into blood by
endocrine (ductless) glands and
d tissues
• Carried by blood to target tissue
es
• Specific hormones only affect certain
c
cells and hormones affect
different cells in different ways
– T
Targett cells
ll possess receptors
t
f r specific
for
ifi h
hormones
– Target cells vary in the transductio
on machinery they possess
– Diverse responses to particular ho
ormones possible
• Effects are typically slower and longer lasting than effects of the
nervous system
Nelson Fig. 2-1
Various intercellular signaling strategies
s
As opposed to:
THE NERVOUS SYSTEM AND THE ENDOCRINE SYST
TEM ARE HIGHLY INTEGRATED!
How do hormones influence the nervous system
m?
Neurogenesis (new neurons))
Apoptosis (death of neurons))
Synaptogenesis (new synapsses)
Neuritogenesis (new inputs)
Conduction velocity
Alter membrane potential
Thus, hormones can act as “neuromodulators”
“
How does the nervous system influence endo
ocrine system?
Neurons secrete hormoness (“neurohormones”)
Neurons induce endocrine glands to secrete hormones
Neurons alter target cell se
ensitivity
Classes of ho
ormones
1.Steroid hormones:
Derived from series of enzymatic modificationss of cholesterol
Androgens like testosterone, estrogens like estrradiol, progestins like
progesterone
t
(androgens,
( d
estrogens,
t
and
d proge
estins
ti are sometimes
ti
referred to as “sex steroid hormones”)
Also,, glucocorticoids
g
like cortisol or corticostero
one and
mineralocorticoids like aldosterone, etc.
2. Fatty acid derivatives (prostaglandins)
Classes of hormones, continued
3. Amino acid derivatives
Thyroid hormone (coupling of two iodin
nated tyrosines)
Amines: Epinephrine and Norepineph
hrine, Melatonin
and Dopamine
4. Peptide hormones
Size range: 3 amino acids (thyrotropin releasing hormone)
to about 200 amino acids (e.g. prolactiin, growth hormone)
-produced
d
db
by ttranscription
i ti off a h
hormon
ne gene, translation
t
l ti off
mRNA, proteolytic processing and othe
er enzymatic
modifications to produce mature peptid
de hormone
Major vertebrate endocrine glands
Endocrine glands:
Ductless
Rich blood supply
Secrete chemical messengers (hormon
nes) into bloodstream
Hormones affect only cells that have ap
ppropriate receptors
Nelson Fig. 2-3
Two key components of endocrin
ne system:
The Hypothalamus and Pituitaryy
Hypothalamus organized into “nuclei”
-clusters of neuronal cell bodies
Nelson 2-4
Intermediate pituitary
Hormones of the
posterior pituitary
(both also produced in
discrete brain regions)
1.
Argin
nine vasopressin (AVP)
Cys-Tyrr-Phe-Gln-Asn-Cys-Pro-Arg-Gly-NH2
or Arginine vasotocin (AVT):nonmammals
C Tyr-Ile-Gln-Asn-Cys-Pro-Arg-Gly-NH2
Cys-Ty
Il Gl A C P A Gl NH2
Physiolog
gical roles: fluid balance and blood
p
pressure
Behaviora
al roles too (pair bonding)
2. Oxytocin or related peptides
gical roles:
Physiolog
S
Smooth
th muscle
m
l contraction
t ti mammary gland,
l d
u
uterus,
male reproductive tracts
Behaviora
al roles too (pair bonding)
Cys-Tyrr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2
To general circulation
Nelson 2-6
Hormone
es of the anterior pituitary
(all peptid
de hormones)
Gonadotrropins:
(in median
eminence)
Luteinizing hormone (LH)
Testosterone synthesis
Induce ovulation
Follicle stimulating hormone (FSH)
Gamete maturation
Estrogen synthesis
Thyroid stimulating
s
hormone (TSH)
Thyroid gland growth
Thyroid hormone synthesis
All are glyycoproteins and share a common alpha subunit
but have different beta subunits that confer specificity
To general circulation
Nelson 2-6
Hormones of the anterior pituitary, continued:
Pro-opiomelanocortin (POMC) gives rise to:
1. Adreno
ocorticotropic hormone (ACTH)
--Glucocorticoid synthesis by
adrenal cortex
-Behavioral
effects too
(learning/memory and food
uptake)
Anterior pit.
ntermediate
pit.
{
ACTH
ACTH
S
{ MSH
CLIP
LPH
LPH
END
LPH
Simplified from Nelson 2-22
2 22
Note: ACTH and endorphin produced in
discrete brain regions as well
END
2. LPH, CLIP: ??
3. Melanocyte stimulating hormone
(MSH): coat, skin color (not in
Humans)
Endorphin (END):
Endogenous opioids, pain modulator
Hormones of the anterior pituitary, continued:
Growth hormone (GH)
Somatic cell growth/ bone growtth via
insulin-like growth factor secretio
on
Metabolic effects (glucose, amin
no acids)
Prolactin (PRL)
Lactation (mammals)
Crop milk production (some bird
ds)
Nutritious secretions (some fish))
Inc bation patch edema (birds)
Incubation
Freshwater adaptation (migratin
ng fish)
Behavioral effects too
Parental care in multip
ple vertebrate species
p
Water drive (salamanders)
Hypothalamic releasing orr inhibiting hormones
(All peptide hormones except dopamine-ma
dopamine ma
ade directly from
tyrosine)
Gonadotropin
p releasing
g horm
mone (GnRH)
(
)
-induces gonadotropin secretion (LH and FSH)
Gonadotropin inhibiting horm
mone (GnIH)
-the opposite (and oth
her things)
Thyrotropin releasing hormo
one (TRH)
-induces TSH secretio
on
Corticotropin releasing horm
mone (CRH)
-induces
i d
ACTH secre
etion
ti
Somatostatin-inhibits GH sec
cretion
Growth hormone releasing hormone (GHRH)
-induces
induces GH sec
cretion
Prolactin inhibiting hormone (PIH): Most likely dopamine
-inhibits PRL sec
cretion
The pineal gland
Secretes melatonin in absence of light
Inhibits reproductive axis in seasonally breeding mammals
Influences sleep/wake cycle
(from tryptophan)
Nelson 2-10
Th th
The
thyroid
id gland
l d
80%
Follicle
TSH
(from
Anterior
te o
Pit.)
Target tissues
20%
Nelson 2-7
The adrenal glands
Sympathetic
input
Nelson 2-9
Aldosterone
(
(Angiotensin
II+)
Cortisol
OR
(ACTH+)
Corticosterone
OR
AND
Adrenal androgens
(ACTH )
(ACTH+)
Epinephrine
Norepinephrine
(from tyrosine)
Sex steroid biosyn
nthesis in the gonads
Progesterone
Pregnenolone
Androgens
5 reductase
Dihydrotestosterone (DHT)
Aromatase
Estrogens
http://www.physci.ucla.edu/research/schlinger/kiranDHEA.httml
11- ketotestosterone (11-KT)
(Important androgen in many fish)
Nonaromatizable to estrogens
M l gonads:
Male
d ttestes
t
FSH
LH
Peripheral tissues,
Testosterone
brain
Nelson Fig. 2-11
Female gonad: ovaries
LH
FSH
Nelson Fig. 2-12
Testosterone
FSH
Estradiol
LH
Estradiol
Progesterone
Peripheral tissues,
brain
Other endocrine glands/tissue
es of note
Parathyroid glands: Parathyroid hormone (calc
cium balance)
Pancreas: Insulin (decrease blood gluc
cose)
Glucagon (increase blood glucose)
Skin: Vitamin D (calcium balance)
Stomach/Duodenum: Secretin (neutrallize acid from stomach)
Cholecystokinin (induce pancreatic
enzy
ymes, bile secretion)
Gastrin (Stoma
ach secretions)
M lti l oth
Multiple
ther peptides
tid iimplicated
li t d
nutriient digestion/absorption and
in fee
eding behaviors
White adipose tissue: Leptin (decrease
e feeding)
Feedback loops often control hormone synthesis
Nelson Fig. 2-36
HOW DO HORMON
NES WORK?
Part I: Hydrophilic (Water so
oluble) Hormones use
membrane receptors: Amin
nes peptide hormones
nes,
Activate 2nd messenger cascades
Gets signal across membrane
Amplifies hormonal signal
Cross-regulation with other signals
s
Can change cell function without new
w protein synthesis
Cell shape, movement, ion ch
hannel activity,
secretion, enzyme ac
ctivity
Can also change cell function via new
w protein synthesis
A very common membrane recepto
or type: G-protein coupled receptor
Peptides
p
Etc.
Cell membrane
Bockaert and Pin, 1999
G protein coupled receptors: cAMP as second messenger
Adenylate
A
cyclase
 subunit of G protein
exchanges GDP for GTP,
activates adenylate cyclase
MODIFIED from Nelson 2-16
Also ion channels,,
transcription factors, etc.
G protein coupled receptors: Calcium as se
econd messenger
Protein
kinase C
Phospholipase C
is activated by GTP bound
G protein  subunit
Substrate
phosphorylation
Additional
kinase activation
MODIFIED from Nelson 2-17
Diversity of effects from same hormone: AVP
A
as an example
V2R
V1aR
V1bR (or V3)
AVP
AVP
Gs
Gq
Gq
Activate Adenylate
cyclase cAMP
Activate Phospho
olipase
C IP3 and Ca2+
Activate Phospholipase
C IP3 and Ca2+
Water reabsorption
i kid
in
kidney
Vascular smooth
m scle contractio
muscle
on
Modulate ACTH release
Behavioral effectss
((Pair bonding)
g)
Part II: Lipophilic, or fat soluble, hormones (steroid hormones and thyroid hormones)
primarily use intracellular receptors, also kn
nown as nuclear receptors
GENERALLY slower acting, and have longer lastin
ng effects than
hydrophilic
y p
hormones
i.e. Cortisol (a lipophilic steroid hormone)- chronicc stress response leads
to elevated blood glucose levels from increased gluconeogenesis, and
increase blood amino acid levels from muscle and connective tissue
protein breakdown (to combat starvation)
Contrast with a hydrophilic hormone:
Epinephrine (bioamine, works via G protein-couple
ed membrane receptor)
-acute stress response leads to reinforcement of sympathetic
s
output
(elevated heart rate
rate, blood pressure) as well as rap
pid elevation of
blood glucose levels
Intracellular (nuclearr) receptor function
?
?
Cytopllasm
Ribosomes
No hormone
R
Nucleus
R
Target gene
Intracellular (nuclearr) receptor function
?
e.g. Estradiol
?
Cytoplasm
2nd messengers etc.
AAA
New mRNA
N
Nucleus
New protein
Best known
th
pathway
R
R
Target gene
Receptor Spec
cificity examples
Ligands
g
((in order of p
potency)
y)
Nuclear receptor
p
17  estradiol=Diethylstilbestrol (DES)
>estrone
Estrogen receptor (ER)
DHT=11- ketotestosterone
>testosterone>>DHEA
Androgen receptor (AR)
Progesterone
Progesterone receptor
(PR)
Glucocorticoid receptor
(GR)
Mineralocorticoid receptor
(MR)
Thyroid hormone receptor
(TR)
Cortisol=corticosterone>>cortisone
Aldosterone
Triiodothyronine>Thyroxine