Transcript Intro. to Behavioral Endocrinology, Third Edition

Chapter 1:
Introduction
&
The Study of Behavioral
Neuroendocrinology
Arnold Adolph Berthold
1803 – 1861
Founder of Endocrinology
A physiologist, zoologist, and
farmer who worked in
Germany.
1.3 Berthold’s experiment
This male is a Eunuch…
He was castrated in childhood and
kept as a servant for the Imperial
Court in China.
The idea of castrating male servants is
seen in many older societies that had
male leaders who wanted to ensure
their servants did not become sexually
active with their spouses.
If castration occurs in humans before
puberty, atypical lengthening of arms,
short stature, and lack of sexual
behavior occur.
If Castration occurs in human males
after puberty, usually no change in
appearance or behavior develops.
1.5 Stages of behavioral research
1.6 How hormones may affect behavior
Figure 11.1: The nervous system’s functions, p. 388.
Sensory input
Integration
Motor output
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
1.7 Change in the testosterone concentrations of sports fans
Classes of Evidence For Research Using Hormone-Behavior Interactions
Three conditions must be satisfied by experimental results to establish a causal link
between hormones and behavior:
1. A hormonally dependant behavior should disappear if the hormone is removed or
the actions of the hormone are blocked.
2. If the behavior stops, replacement of the hormone will restart the behavior.
3. Hormone concentrations should be directly related (covariant). This would mean
the higher the hormone concentration, the greater the display of the behavior.
However, problems arise because hormonal signals are long lasting.
Common Techniques Used in the Study of
Endocrinology (Behavioral Endocrinology)
(You will see 14 different techniques.)
Technique #1: Ablation and Replacement
This method is like that employed by Berthold. It is the removal (ablation) of a
suspected hormone source or by replacement via implantation or by injection of
suspected hormonal chemicals
Technique #2: Bioassays
Identifies the chemical processes in a hormone’s actions and involves testing
the hormone on a living animal or cell culture.
Interestingly, the bioassay can often usefully be conducted on alternate species
from which a hormone has been derived.
“The Rabbit Test” is perhaps the most famous example of a bioassay involving
two different species. This was developed in 1929 and was used to detect
human pregnancies until the late 1950s. It tested for the presence of human
chorionic gonadotropin (hCG).
1.8 A bioassay for prolactin
In this case, the cell height
of the crop sac is going to
differentiate dependant upon
the amount of prolactin
injected.
Technique #3: Immunoassays
The most famous form is the radioimmunoassay (RIA) and it is a technique that
was first able to measure hormones PRECISELY. Rosalyn Yalow received the
Nobel Prize in 1977 for her work on this technique.
1.9 Radioimmunoassay
Technique #4: Immunocytochemistry
A technique that it uses antibodies to determine the location of hormones or
hormones receptors. Often these antibodies are attached to a fluorescent
dye for viewing under a fluorescent microscope.
ICC Without Fluorescent Dye
ICC With Fluoroscent Dye
Technique #5 - Autoradiography
Radiolabeled hormones are injected into a tissue or animal and the
sections taken will reveal sites of absorption and radioactivity.
Technique #6 – Blot Tests
A cellular technique that is used to discern if a particular protein (or
nucleic acid is found in a given tissue. The various forms of these
techniques involve electrophoresis of homogenates of tissues from
which proteins are extracted. Electrophoresis will separate these
proteins on the basis of electrical charge.
Technique #7 – “in-Situ” Hybridization
A technique that will allow examination of gene expression in cells,
tissues, or organs are identified for a specific protein.
Technique #8 – Stimulation Followed With Recordings
Direct electrical stimulation of neuronal pools (brain, spinal cord, or
peripheral nerves) can elicit electrical activity in cells and tissues of
neurall relevant sites.
Rat with electrodes implanted in
the brain to allow stimulation of
specific regions of the
hypothalamus (a major
endocrine secreting region).
Technique #9 – Pharmacological Techniques
The use of chemical agents that may alter the action
or function of a hormone. The two major groups are
refered to as:
AGONISTS – hormone mimics
ANTAGONISTS – hormone blockers
These compounds can be administered to an animal
in a variety of ways but the two most common forms
are:
CANNULATION – a form of permanent form of
injection tube is implanted in a target region. Used
typically for multiple administrations of a
pharmacological agent.
SIMPLE INJECTION – using syringes to administer a
single dose of a pharmacological agent
Technique #10 – Anastomosis
An older technique whereby the blood systems of two different
animals is interconnected to study the endocrine systems of the two
animals.
Technique #11 - Microdialysis
Much like kidney dialysis, it is a technique that allows the
administration of very minute quantities of
neurotransmitters, hormones and/or other
pharmacological agents into a conscious animal. But
the experimental benefit is that samples (chemical or
electrical) from the site are also possible.
Technique #12- Brain Imaging
Scanning techiques of various forms that are
used to remotely monitor and test the activity of
body structure function… especially that of the
brain. There are several types of these devices
including:
Positron Emission Tomography (PET) - will show
functioning of brain regions in real time.
Computer Assisted Tomography (CT) – uses xrays to give a 3-D image of the brain within a
particular plane of space.
Magnetic Resonance Imaging (MRI) - using nonionizing radiation energy to see images similar to
CT scans.
1.15 Engineering knockout mice (Part 1)
Technique #13 –
Genetic
Manipulations
1.15 Engineering knockout mice (Part 2)
#14 – Gene Arrays
Often called microarrays. This tool is capable of showing the expression
(activity) of genes within an animal’s genome.
Leptin – both mice have a defective ob gene, resulting
in development of obesity. The mouse on the right was given daily injections
of the leptin protein, the protein that the ob gene encodes.