Ch. 1: The Study of Behavioral Endocrinology

Chemical messengers released from endocrine glands that travel through the blood system to influence the nervous system to regulate the physiology and behavior of an individual; change gene expression or the rate of cellular function; increase probability of behavior occurring

Hormonal Affects
Increases the probability that a specific behavior will occur in the presence of a particular stimulus by affecting individuals’ sensory systems, integrators, and/or effetors

Generally thought of as involving movement but can be nearly any type of output, such as a color change

Four Interacting Levels of Analysis to Explain Behavior
1) Immediate causation 2) development 3) evolution 4) adaptive functioncvx

Behavioral Endocrinology
The study of the interaction between hormones and behavior; very interdisciplinary

For psychology and behavioral endocrinology: “Short but long history”

“Hormones and Behavior”
Book published by Beach in 1948 that was the recognized start of behavioral endocrinology

Male sex organs that produce and secrete a hormone called testosterone that influences sexual behavior, aggression, territoriality, hibernation and migration as well as many other behaviors that differentiate males from females; outside of body

Surgical removal of testes; historically been the most common manipulation of the endocrine system; animals castrated to make better meat; Aristotle recorded the affects on roosters and men

Royalty employed men castrated before puberty to guard women from other men; no big affect on appearance or sexual behavior if it occurs after sexual maturity; before sexual maturity: short state and long arms and sexual behaviors unlikely to develop as well as other puberty markers such as the thickening of vocal chords to deepen voice

Berthold’s Experiment
19th century experiment that is considered the first formal study of endocrinology; conclusively demonstrated that a substance produced by the testes could travel though the bloodstream and eventually effect behavior by demonstrating that a product of the testes was necessary for a cockerel to develop into a normal adult rooster. He placed 6 cockerels in 3 experimental groups of two birds; first group castrated–> capons; 2nd group castration and reimplantation of singular testes–> normal roosters; 3rd group castrated and switched one testis–> normal roosters; testis had attached to intestine grew and developed vascular supply with sperm

Difference between Rooster and Capon
Roosters are larger with plumage, but castrated ones do not nor do they attempt to mate with hens and avoid aggression; capons also do not crow

Conclusions of Berthold’s Experiment
1) Testes are transplantable organs 2) transplanted testes can function and produce sperm 3) because the testes functioned normally after all nerves were severed there are no specific nerves directing testicular function; thus concluded that a secretory blood-borne product of the transplanted testes was responsible for the development of birds; important to note that 3 of the 4 parameters used to establish this were behaviors

Pangenesis Theory of Inheritence
Early idea prior to discovery of chromosomes and gene functions that held that all body parts actively discharge bits and pieces of themselves into the blood system, where they are transported to the ovaries or testes and assembled into miniature offspring; affected Berthold’s concepts: 1) various parts of the body release specific agents in the blood 2) agents travel through blood stream to specific organs

Ernest Starling
coined the term hormone by studying a messenger secreted by the duodenum that stimulated pancreatic secretions in dogs, a process previously considered to be regulated by the nervous system

Organic chemical messengers produced and released by specializing glands called endocrine glands into the bloodstream where they may act on target organs or tissues at some distance from their origin; coordinate the physiology and behavior of an animal by regulating, integrating, and controlling its bodily function; example: chemical that produces gametic maturation also promotes mating habits

Endocrine Glands
Produce and secrete hormones

the chemicals used by the nervous system in coordinating animals’ activities, but at a lesser distance and shorter amount of time than hormones; similar to hormones

Chemical signals produced by cells of the immune system that are similar to hormones and may interact with hormones to affect behavior especially when ill

Endocrine Disrupters
Certain chemicals that can mimic natural hormones because of their structure in specific environments and can affect hormone-behavior pathways as natural hormones

The distinguishing factor that allows a cell to be influenced by a specific hormone; interaction leads to a series of cellular events that eventually lead either to activation of enzymatic pathways or to effects on gene expression and protein synthesis which can activate or deactivate genes causing another cascade of cellular events

Target Cells
Cells with the specific receptors for a hormone; specific numbers of receptors must be available to produce any effects

Individual Differences in Hormone-Based Behavior
Mainly due not only to the levels of hormone in the blood, but also reflect complex influences of hormone concentrations, patterns of hormone release, numbers and locations of hormone receptors and the efficiency of those receptors in triggering signal transduction pathways that ultimately affect gene transcription

Hormones Effects on Cells
1) alter the rate of normal cellular function 2) change their morphology or size 3) affect neuronal growth and development and apoptosis

Neural Transmission v Hormonal Communication
Hormonal communication travels further and to more places; neural travels faster and is used for more immediate communication; hormones slower and long term growth, development, reproduction, and metabolism; more control with neural than hormonal communication

Neural Transmission
In response to a neural impulse at a presynaptic terminal, there is an influx of calcium ions that cause vesicles containing neurotransmitters to move toward the presynaptic membrane, fuse with it and cross the synaptic cleft to receptors

Hormonal Communication
Manufactured in the Golgi apparatus of an endocrine cell, move toward membrane in vesicles that then release them to the bloodstream where they eventually bind to specific receptors

Output organs; mainly muscles that display coordinated behavior

Problems of Behavioral Research
1) Abstraction or bias is inevitable 2) Determining what other behaviors may relevant to elucidate the behavior being examined 3) To understand the causes (hormonal or otherwise) of any behavior we must thoroughly describe it and establish what is normal

Goal of Behavioral Scientists
To determine what behaviors are relevant to the question begin asked, to describe those behaviors, and to interpret their functions

The Simple System Approach
To untangle the contributions of various factors to hormone-behavior interactions, behavioral endocrinologists perform experiments in controlled environments with most research involving only a few types of simple behavior because of too much variation in complex and make it easy to replicate and quantify but easy to overlook subtle interactions such as social and environmental clues

Levels of Analysis
After collecting ample description of behavior, a hypothesis is developed and is tested by means of observation and experimentation; generally What causes animal A to emit behavior B?; 4 answers through 4 different levels of analysis: immediate causation, development, evolution, and adaptive function

Immediate Causation
Level of analysis; underlying physiological, or proximate, mechanisms responsible for a given behavior usually mediated by nervous or endocrine systems which influence behavior on a moment to moment basis during the life of an individual. Various environmental and internal stimuli as well as sensory and perceptual responses regulate this and thus experiments usually use physiological methods such as alterations of hormone concentrations or direct manipulations

Level of analysis; behavioral responses and repertoires of animals change throughout their lifetime as a result of the interaction between genes and environmental factors; questions addressing this concern the full range of the organism’s life

Level of analysis; involves many generations of animals and address the ways that specific behaviors change during the course of natural selection. Study the evolutionary bases of behavior to learn why behavior varies between closely related species as well as to understand the specific behavioral changes that occur during the evolution of new species; relies on extant species that are related

Adaptive Function
Level of analysis; synonymous with questions of adaptive significance; concerned with role that behavior plays in the adaptation of animals to their environment and with the selective forces that currently maintain behavior

Proximate Causation
How questions; immediate causation and development level of analysis

Ultimate Causation
Why questions; evolutionary and adaptive levels of analysis

3 Interacting Components of Animals
1) input systems (sensory) 2) integrators (central nervous system 3) output systems or effectors (muscles); hormones could affect one, two, or all three of the systems that can aid in the design of hypotheses and experiments to explore

Anecdotal Evidence
Lighthouse keeper beard story; not compelling evidence; lighthouse story didn’t work because 1) only one experimental subject was used 2) subject was aware and maybe biased 3) other conditions could have accounted for changes

Conditions that Must be Satisfied by the Experimental Results to be Linked
1) A hormonally dependent behavior should disappear when the source of the hormone is removed or the actions of the hormone are blocked. 2) After the behavior stops, restoration of the missing hormonal source or its hormone should reinstate the absent behavior. 3) Finally, hormone concentrations and the behavior in question should be covariant; that is, the behavior should be observed only when hormone concentrations are relatively high and never or rarely observed when hormone concentrations are low (hardest to prove because of long latency of action and because pulsatile manner); only really need first two

Removal or extripation of the suspected source of a hormone to determine the function; Berthold’s experiment example; 1) a gland is suspected to be the source of a hormone affecting a behavior is surgically removed 2) the effects of removal are observed 3) the hormone is replaced by reimplanting the removed gland, by injecting a homogenate or extract from the gland 4) a determination is made whether the observed consequences of procedure have been reversed by the replacement therapy

The result of an ablation in the brain complementary approach to ablation that is instead an observation

a test of the effects of the hormone on a living animal; doesn’t need to use the same species of where the hormone came from to the affect; injecting rat blood into a pigeon to see the amount of crop sac milk produced and thus measuring the amount of prolactin present in the blood by looking at the dose-response curve previously recorded by injecting purified prolactin and measuring the milk; rabbit test for gonadtropin causing corpeal luteal; contamination is a big concern for a bioassay so less used now because more technology

Behavioral Bioassays
Prolactin causes newts to seek out water; the more prolactin the faster they seek water; require rigorous standardization of test conditions for accuracy and reliability

Radioimmunoassays (RIA)
More precise than bioassays; based on the principle of competitive binding of an antibody to its antigen; an antibody possesses a given number of binding sites for its antigen; antigen can be labeled with a radioactive; first inject hormone of interest into an animal to raise antibody which is then collected from the animal’s blood and purified; standard curve is created by reaction tubes that all contain the same amount of radiolabeled hormone and different amounts of cold purified hormone of known concentration; radiolabeled hormone and cold hormone compete for binding sites on an antibody so the more cold hormone there is the less hot hormone will bind to an antibody; done with samples and then compared to curve

Enzymoimmunoassay (EIA or Enzyme-Linked Immunosorbent Assay (ELISA)
Works on the principle of competitive binding of an antibody to an antigen; major difference from an RIA is that this procedure does not require radioactive tags; instead tagged with an enzyme that changes the optical density of a substrate molecule; meant to provide quantitative data of how much there is; standard curve created with wells that have a specified amount of hormone and create a gradient read by a spectrometer; sample added and then interpolated to standard curve

Immunocytochemistry (ICC)
Technique, similar to an immunohistochemistry but with cells instead of tissues,that uses antibodies to determine the location of a hormone in the body; antibodies linked to a marker molecule such as florescent dye and are introduced to a dissected tissue of an animal floating in a solution where they bind with hormones or neurotransmitters of interest; sometimes need to label it by taking a secondary antibody that targets the primary antibody that is conjugated with a tag such as a fluorescent marker that lights under microscope and light and that will show through

Since hormone receptors are selectively concentrated in particular target tissues, such as estrogen receptors in the uterus, this technique can determine hormonal uptake and indicate receptor location; animal is injected with a radiolabeled hormone, or in vitro; suspected target tissue is then into several very thin sections; some sections are dyed to show various cellular structures; other area is in contact with photographic film or emulsion for some period of time and the emission of radiation from the radiolabeled hormone develops on image on the film that is then compared to the stain section to determine areas of concentration compared with cell structure; good for nervous tissue

Blot Tests
Technique that determines whether or not a particular protein or nucleic acid is present in a specific tissue; the tissue of interest is homogenized and the cells are lysed with detergent; the resulting homogenate is run on a gel that is subjected to electrophoresis; transferred to a membrane that is then incubated with a labeled substance that can act as a tracer for the protein or nucleic acid such as a radiolabeled complement or an antibody or enzyme; if radioactive, film is used to locate and measure; enzyme of chromogenic chemicals; DNA ones called Southern blotting; RNA Northern; proteins Western

The application of an electric current through a matrix or gel that results in a gradient of molecules separating out along the current on the basis of size molecules (smaller molecules move farther than larger molecules during a set period of time) which is then transferred to a membrane

Autoradiography Using In Sity Hybridization
Tool to examine gene expressions; identifies cells or tissues in which mRNA molecules encoding a specific protein, such as a hormone or neurotransmitter, are being produced; tissue is fixed, sliced very thin, mounted on slides, and either dipped into emulsion or placed over film and developed with photographic chemicals; typically also counterstained to identify cellular structures; radiolabeled cDNA probe is introduced into the tissue and hybnidize with the mRNA if it exists and appear as dark spots; can show whether a particular substance is produced in a specific tissue and not just if it is there and recently quantifications; more sensitive than blot too

Electrical Stimulation
Turns on specific neurons or brain centers to discover the effects of various endocrine treatments on the central nervous system; electrode is precisely positioned in the brain and a weak electric current is used to stimulate neurons; studies the release and inhibiting hormones of the hypothalamus

Single-Unit Recording
Technique that monitors the electrical activity of single neurons by placing very small electrodes in or near an individual neurons to record changes in their activity during and after immediately exposing them to hormones; can help uncover the direct effects of various endocrine products on neural activity; usually with multiple

Mimics for medical purposes of hormones and neurotransmitters that have been identified that inform us about the functioning of the endocrine and neuroendocrine systems; stimulate endrocine system by affecting hormone release

Blockers for medical purposes of hormones and neurotransmitters that have been identified that inform us about the functioning of the endocrine and neuroendocrine systems; inhibit endocrine system by affecting hormone release

Technique where hollow electrodes or fine tubes are inserted into specific areas of the brain and used to introduce substances; can help identify the area that the chemical acts on the brain; can be put into the circulatory system as well

Technique where the blood systems of two animals are connected via cannulation tubing to see if the endocrine condition of one animal can cause a behavioral change in the other

Technique based on the principle of dialysis in which a semipermeable membrane that allows passage of water and small molecules divides two fluid compartments; allows assessment of responses to neurotransmitters, drugs, and hormones in a conscious animal; done by implanting a cannula in the brain region of interest using stereotatic surgery; the end of one compartment is continuously perfused with a liquid and molecules are exchanged signaling molecules can be monitored via the second compartment; can be done in awake moving animals; analyzed with HPLC to detect such substances

Positron Emission Tomography (PET)
Important technique for scanning to determine regional brain activation; detailed measurements of real-time functioning; give patient small amount of radioactively tagged molecules tat mimics glucose or radioactive gas that emits positrons and is taken up at high rates in the most active neurons; when a positron collides with an electron the collision produces two gamma rays that leave the body in opposite directions detected by the PET scanner; then picture

Computerized Tomography (CT)
Scanner that shoots fine beams of X-ray into the brain from several directions; emitted information is fed into a computer that constructs a composite picture of the anatomical brain of the person

Magnetic Resonance Imaging (MRI)
Very similar to CT, but uses non-ionizing radiation formed by the excitation of protons by radio-frequency energy in the presence of large magnetic fields; assesses irregularities

Functional MRI (fMRI)
Uses a very spatial and temporal resolution to detect changes in brain activity during specific tasks or conditions; detects the change of blood flow since activation of neurons requires more glucose and oxygen and thus more blood

Transgenic Manipulation
Common genetic manipulation in behavioral endocrinology that is an insertion of genetic instructions encoding a hormone or the receptor for a hormone

Knockout Manipulation
Common genetic manipulation in behavioral endocrinology that is the removal of genetic instructions encoding a hormone or the receptor for a hormone; do this by scrambling the order of the nucleotides that make up the gene; first identify gene, target, and mark precisely; next, a mutated form of the gene must be created; harvest mouse embryonic stem cells and culture them; introduce the mutated gene by microinjections; small number of the altered genes will be incorporated into the DNA of the stem cells through recombination and then inserted into normal mouse embryo and surrogate mothers

An animal that comes from an embryo with mutated cells; some of the cells will be normal descendants and some will have the mutant gene; incorporated into germ line and then some of the offspring will be heterozygous for the trait then bred with other heterozygous until homozygous offspring

Gene Silencing with RNA interference (RNAi)
Endogenous gene regulatory mechanism that inhibits gene expression by impeding either transcription of specific genes or translation of the gene product into a protein; short interfering RNA (siRNA) are key to the process; specific RNAi pathway proteins are chaperoned by the siRNA to the targeted mRNA where they break down the molecular target into increasingly small pieces that no longer can encode protein; related type of RNA is transcribed into the genome itself and is called microRNA (miRNA)

Short Interfering RNA (siRNA)
A class of double stranded RNA molecule 20-25 nucleotides long; specific RNAi pathway proteins are chaperoned by the siRNA to the targeted mRNA where they break down the molecular target into increasingly small pieces that no longer can encode protein; related type of RNA is transcribed into the genome itself and is called microRNA (miRNA); can be harnessed for medical research

The process of adding DNA into cells with the goal of affecting protein expression of the transgene of interest; accomplished via viruses or plasmids (bacterial) mechanisms; use viruses to deliver viral vectors (especially retroviruses); used green florescent protein a lot to label and track cells ; less reliable than gene knockout; can also use physico-chemical techniques to provoke

Get access to
knowledge base

MOney Back
No Hidden
Knowledge base
Become a Member