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

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Sensory input

Motor output

Integration

1.7 Change in the testosterone concentrations of sports fans

These measures occurred after the conclusion of the 1994 World Cup. You may be able to guess that Brazil won the match.

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 x-rays to give a 3-D image of the brain within a particular plane of space.

Magnetic Resonance Imaging (MRI) - using non-ionizing 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, resultingin development of obesity. The mouse on the right was given daily injections

of the leptin protein, the protein that the ob gene encodes.