Psych 4644 - Hormones & Behavior Exam 1

Behavioral endocrinology

the study of hormone-behavior interactions;

multidisciplinary;

emerged with Frank Beach publication (1948)

Eunuchs

men castrated before puberty

unlikely to develop sexual behaviors

never develop beards

voice doesn't change

employed by royalty

Castrati

young boys who are castrated to prevent changes in singing pitch

some became famous opera singers due to high voices

First formal experiment in endocrinology

Conducted by A. Berthold in 1849;

Roosters & Capons;

Concluded that the testes produced a blood-born product that affects anatomy and behavior

Hormones

chemicals produced and released in very small amounts by endocrine glands into the bloodstream

pulsatile secretion

hormones are not released constantly but instead are released in spurts

The relationship between hormones and behavior

is bidirectional: hormones affect behavior and behavior feeds back to affect hormones;

environmental factors are also involved

Principal actions of hormones:

1) metabolism

2) growth

3) developmental processes

4) behavior

Hormones produce biological effects by:

traveling to specific receptors and regulating cell events that lead to activation of enzymes, gene expression and protein synthesis

Hormonal communication is:

released into CIRCULATORY SYSTEM

travels LONG DISTANCES (1mm-2m)

can travel ANYWHERE in the body

SLOW, GRADED

mediates LONG-TERM PROCESSES

LITTLE voluntary control

Neural communication is:

neurotransmitters released into SYNAPES

travels SHORT DISTANCES (20-30mm)

can ONLY travel along neural tracts

FAST

mediates FAST CHANGES

SOME voluntary control

Behavior

usually considered output-movement but responses like no movement, excretion of scents and chemicals, changes in skin coloration and many other nonmuscular effector systems can be affected by hormones

Field studies

studies take place in natural habitat

ecologically relevant

genetic, social and environmental variables can influence hormones and behaviors-> CANNOT be controlled

Laboratory studies

simple system approach

studies genetically similar animals in controlled environment

allow researchers to monitor the animal throughout it's life without influence of other factors

Levels of Analysis of examining causes of behavior

HOW?/proximate

mechanism

development

WHY?/ultimate

evolution

adaptive function

Mechanism

underlying physiological mechanisms responsible for a given behavior, most commonly used by behavioral endocrinologists

Development

full range of organism's behavior across the lifetime from conception to death

Adaptive function

involve many generations of animals and dress the ways that specific behaviors change during the course of natural selection, relies on comparing existing species in relatedness

Evolution

role that behaviors plays in the adaptation of animals to their environment and with the selective forces that maintain behavior

Hydraulic model

reflexive-fixed action explanation but

....Hormones DO NOT CAUSE behavior they change the probability that a particular behavior will be displayed

hormones do not act like "faucets" in which behavior spews forth if the hormone spigot is open

components found that hormones could act on to affect behavior:

INPUT (sensory) systems (estrogen - physical appearance)

Intergrators (CNS) (estrogen - changes in neural architecture)

OUTPUT ( effector) systems - estrogen could affect muscles)

hormone and behavior relationship example: Testosterone levels in winning team

are higher than losing team in human studies and in animal studies (mice and monkeys)

Classes of evidence

1) removal of hormone should eliminate behavior

2) replace hormone should reinstate behavior

3) hormone concentrations and behavior in question should be covariant (behavior only observed when hormone levels are high never/rarely when low)

bioassay

tests the effects of a hormone on a living animal

USES:

to detect the presence/absence of a hormone

(rabbit ovary structure changes in presence of HCG (human female pregnancy test)

for quantitative measurement (height of crop sac when prolactin is/is not present; increases when present)

rabbit test

two detect hCG=human chorionic gonadotropin to detect pregnancy if present -> indicate woman was present

pigeon crop sac test

prolactin involved in lactation in humans, crop sac in pigeons prepares milk-> prolactin makes crop sac larger by stimulating epithelial cells

dose-response curve: inject known amounts of prolactin into crop sac, increase dose of prolactin-> higher the crop sac

immunoassays

used to determine whether a hormone is present and to measure hormone concentrations

easier, require less animals and more accurate that bioassays

radioimmunoassay (RIA)

competitive binding

injected into animal to raise antibody

measures radio activity radiated from "hot antigen"

"cold antigen" is normal

enzymoimmunoassay (EIA)

doesn't require a radioactive tag, antibody is tagged with chromogenic compound that changes color when it binds to antigen (hormone)

give yes or no answer

ex. home pregnancy test

enzyme linked immunosorbent assay (ELISA)

quantitive, wells coated with antibodies, add samples containing antigen to wells (unlabeled hormone) and antigen label with chromatin which will compete for binding sites on antibody

more color=less unlabeled hormone

less color= more unlabeled hormone

ablation and replacement

1) source of hormone is surgically removed

2) effects of are observed

3) hormone is replaced by re-implantation or injecting purified hormone

4) observe whether the effects of ablation are reversed

brain lesion

1) part of the area is destroyed by:

electrolytic (electrical current) applied

neurotoxic (chemical) injected

2) effects of lesion are observed

electrical stimulation

turns on specific brain region

i.e. if mPOA is electrically stimulated male sexual behavior is facilitated (exhilarates ejaculation in male rates)

electrophysiological recording

monitors electrical activity of neurons

can reveal what parts of the brain are involved in a particular behavior and can uncover how neural activity is affected by hormones

western blot

technique to determine whether or not a hormone/hormone receptor is present in the brain and where

make a brain smoothie

cannot localize protein to a specific cell type or nuclei

antagonists

BLOCK

INHIBIT hormone production or release

agonists

MIMIC

STIMULATE hormone production or release

immunocytochemistry

used to determine the location of a hormone or a hormone-receptor

staining of brain with dye

thin slices of tissue expose to a solution of antibody to linked to a fluorescent dye or chromogen

autoradiography

used to determine hormonal uptake and indicate receptor location

in situ hybridization

identifies brain regions/cells in which mRNA encoding a specific protein are being produced

cDNA is used to radiolabel brain tissue if mRNA is present cDNA will form a tight association/hybridize with it

once developed, the radio labeled cDNA and the mRNA will appear dark spots

qPCR

can also be used to measure mRNA but in ground up tissue

tract tracing

ways to uncover these more complex neural circuitry

anterograde

retrograde

anterograde tracing

source/soma-> termination/synapse

tracer injected to region of interest-> absorbed in cell-> transported down axons->target

using immunohistochemistry

can visualize axonal projections

retrograde tracing

synapse-> soma

tracer injections are made at fiber terminal and transported to cell bodies to examine cells projecting to those locations

immediate early genes

proteins of IEGs are detected by immunocytochemistry

IEGs = first genes that are turned on

helps identify neuronal circuits involved in hormone-behavior interactions

"knockout mouse"

removal of gene that encodes for spedific protein

lacks gene throughout life

inducible knockouts

"knock in mouse"

gene replacement by mutated version of same gene

transgenic

introduction of genes into the mouse genome

antisense oligonucleotides

blocks translation of a specific mRNA

provides temporal and spatial specificity

viral-mediated gene delivery

gene of interest over-expressed to see how hormones, brain and behaviors changes as a result, replace

optogenetics

tool for manipulating neural activity

use different wavelengths of light, delivered via fiber optic cable, to activate or inhibit neurons that have been genetically modified to express light-sensitive ion channels

histology

used to visualize cells and their structures

chemical stains applied to brain tissue

used to address how hormones or behavior alter the number of cells in certain brain areas or the structure of those cells

nissl stain

stains cell bodies of neurons

used to measure cell body size and number of cells in particular region

golgi stain

used to examine how hormones or behavior changes the morphology of neurons (dendrite length, branching of dendrites, dendritic spines)

darly stains full neuron

computerized tomography (CT)

xrays from all different angles which a computer then combines to create a composite picture showing anatomical details within a slice through a person's brain

magnetic resonance imaging (MRI)

uses magnetic field and radio waves to create structural images of the brain

positron emission tomography (PET)

involves injecting a radioactive substance (e.g. glucose) into the bloodstream, which is then taken up by parts of the brain according to how active they are

functional magnetic resonance imaging (fMRI)

detects increases in oxygen level during neural activity

gene wide association

used to find genetic variations associated with a particular condition

endocrine system

consists of endocrine glands which have cells that release chemical messages (i.e. hormones) into the blood stream

rich blood supply

hormone receptors - lock

hormones - key

paracrine signaling

secrete products that affect adjacent cells

ex neurons

autocrine signaling

secrete products that feedback to influence the same cells that originally produced them

ex. steroid hormones

endocrine signaling

signaling cell secrete product that go through bloodstream to target cell

endocrine glands

are ductless

secrete hormones directly into the blood

does include secretions of tissues that are not entirely glandular in nature (e.g. pancreas and brain)

exocrine glands

have ducts/tubes into which their secretions are released

ex. salivary, sweat, mammary glands

general features of endocrine system

endocrine glands have a rich blood supply to speed up transport of hormones

hormones can travel in the blood to virtually every cell in the body and can interact with any cell that has appropriate receptors

what determines a hormonal response

hormone concentrations

patterns of hormone release

numbers and locations of hormone receptors

efficiency of those receptors in triggering intracellular events

pineal gland

called the epiphysis

located within the brain between telencephalon and diencephalon

secretory cells are call prinealocytes

produce and secrete MELATONIN

over course of evolution function of pineal cells has shifted from photoreception to neurosecretion

hypothalamus

located below thalamus

made up of groups neuronal cell bodies (nuclei)

in median eminence, specialized neurons called neurosecretory cells secrete neurohormone (from a neuron) into the pituitary

receives and integrates neural info from higher brain areas

not shielded by BBB like other brain regions

gonadotropin releasng hormone (GnRH)

hypothamalic releasing hormone - GnRH

reproductive hormones

corticotropin releasing hormone (CRH)

hypothamalic releasing hormone - CRH

stimulates pituitary gland, to secrete ACTH

thyrotropin releasing hormone (TRH)

hypothamalic releasing hormone -TRH

acts on thyroid gland stimulating it to produce thyroid hormones which regulates metabolism

somatocrinin (GHRH)

hypothamalic releasing hormone

body growth

somatostatin (GH inhibiting hormone)

hypothamalic inhibiting hormone - GH

dopamine (DA)

hypothamalic inhibiting hormone

prolactin inhibitory hormone (PIH)

melanotropin inhibitory hormone (MIH)

neurohormone

hormones released by neurons

pituitary gland

called the hypophsis

connected to base of hypothalamus by infundibulum

master gland, highly regulated

posterior and anterior

anterior pituitary (AP)

neurohormones from the hypothalamus reach the AP via the portal blood system

causes release of tropic hormones that stimulate various physiological processes either by acting directly on target cells or by causing other endocrine glands to release hormones

posterior pituitary (PP)

hormones are secreted directly from neurons into the blood

oxytocin

vasopressin

oxytocin (PP)

hormone responsible for social, reproductive and parental behaviors, uterine constractions during childbirth, milk let down

vasopressin (PP)

antidiuretic hormone (ADH) or arginine vasopressin (AVP)

targets kidneys and arteries

water balence, blood pressure

gonadotropins

luteinizing hormone (LH) - AP

follicle stimulating hormone (FSH) - AP

hypothalamus releases GnRH-> pituitary released LH and FSH-> targets ovaries/testes

stimulate hormone production in the gonads as well as the development and maturation of gametes (sperm & eggs)

thyroid stimulating hormone (TSH)

thyrotopes

hypothalamus release TRH-> pituitary releases TSH-> stimulates thyroid

prolactin (Prl)

hypothalamus releases TRH-> pituitary releases prolactin-> acts on mammary glands to promote lactation and many other functions

growth hormone (GH)

hypothalamus releases GHRH-> pituitary releases GH-> stimulates (or inhabits) growth directly or via production of growth related substances

GHIH inhibits GH release

too much GH: acromegaly in adults; gigantism in children

GH deficiency in children can result in short stature

adrenocorticotropic hormone (ACTH)

hypothalamus releases CRH-> pituitary releases ACTH-> stimulates the release of glucocorticoids from adrenals

thyroid gland

H-shaped structure that partially surrounds upper trachea

consists of many sphere-shaped follicles that produce, store and secrete thyroid hormones

unique because it can STORE a large amount of hormone

triiodothyronine (T3) & thyroxine (T4)

thyroid hormones released in response to TSH from the AP

derived from the amino acid tyrosine

require iodine for their production

thyroid hormones functions

alter growth

influence reproduction

affect metabolism

disorders of the thyroid

goiter

cretinism

hyperthyroidism

hypothyroidism

goiter

lack of iodine

cretinism

stunted body growth, facial malformation, reduced brain size and intellectual disability

hyperthyroidism

overactive thyroid, weightloss, fast heartbeat, sweating, anxiety

grave's disease

hypothyroidism

underachieve thyroid, weight gain, fatigue, depression, increased sensitivity to cold, puffy face, irregular menstrual cycles

Hashimoto's thyroidosis

parathyroid gland

behind thyroid

produces parathyroid hormone (PTH)

involved in calcium regulation

pancreas

underneath liver and in curve of small intestine

both an endocrine and exocrine gland

secretes digestive juices into the intestines

endocrine tissues are embedded in exocrine tissues called islets of langerhans

insulin, glucagon, somatostatin

insulin (b cells)

pancreatic hormone

lowers blood sugar by promoting the liver to store glycogen

glucagon (a cells)

pancreatic hormone

increases blood sugar by stimulating the breakdown of glycogen in the liver

somatostatin (s cells)

pancreatic hormone

inhibits release of insulin and glucagon locally within pancreas

gastrointestinal (GI) tract

endocrine tissues of the GI tract are scattered through the gut, NOT located in a single glandular organ

GI hormones regulate cells and organs in which they are produced

gastrin

secretin

cholecystokinin (CCK)