Methods in Human Behavioral Neuroendocrinology

1. Methods in Human Behavioral Neuroendocrinology 1. EXPERIMENTAL STUDIES --> MANIPULATE an independent variable --> MEASURE the dependent variable --> Can discuss a CAUSE-EFFECT relationship

2. Methods in Behavioral Neuroendocrinology 1. EXPERIMENTAL STUDIES 2 major types in behavioral neuroendocrinology A. Behavioral responses to neuroendocrine manipulations B. Neuroendocrine responses to behavioral manipulations

3. Methods in Behavioral Neuroendocrinology 1. EXPERIMENTAL STUDIES A. Behavioral responses to neuroendocrine manipulations In this type of experiment : IV : Manipulated hormone levels DV : Measured behavior Now, how can we MANIPULATE hormone levels?? --> Hormone Removal and Replacement Protocol

4. Methods in Behavioral Neuroendocrinology In order to show that a particular behavior is MODULATED By a given hormone, this behavior has to change in Concomittance with changes in hormone levels Stages : 1. Remove hormone from circulation --> behavior 2. Restore hormone levels (replacement) --> behavior 3. Variations in hormone concentrations should be correlated with changes in frequency and intensity of behavior

5. Methods in Behavioral Neuroendocrinology 1. Hormone removal : 3 general methods A. Surgical : Ablation of endocrine gland secreting hormone e.g. ovarectomy, adrenalectomy etc. Problem : Since many glands produce more than one hormone, ablation will induce confounder effects e.g. adrenalectomy : Decreases in GC, estrogen, progesterone, etc.

6. Methods in Behavioral Neuroendocrinology 1. Hormone removal : 3 general methods B. Pharmacological : Can use drugs to prevent the synthesis of a particular hormone, or to antagonize a hormone at the level of its receptor e.g. metyrapone : inhibitor GC RU486: Antagonist Progesterone

7. Methods in Behavioral Neuroendocrinology 1. Hormone removal : 3 general methods C. Immunological : Can develop antibodies for hormones. These antibodies will inactivate the hormone of interest and prevent it from activating its receptor.

8. Methods in Behavioral Neuroendocrinology 2. Hormone Replacement : 3 general methods A. Gland Replacement : Transplantation of new or ablated gland (Berthold, 1949) E.g. Transplant pituitaries under the kidney. Free from inhitibing factors of hypothalamus, these pituitaries can significantly increase prolactin levels.

9. Methods in Behavioral Neuroendocrinology 2. Hormone Replacement : 3 general methods B. Injection of purified hormones : Take the purified hormones from the ablated gland and inject them to organism. Can take purified hormones from other Ablated glands (cow, pigs, etc). Problem : some hormones are species- specifics so cannot do that E.g. Human Growth Hormone

10. Methods in Behavioral Neuroendocrinology 2. Hormone Replacement : 3 general methods C. Injection of synthetic hormones: If knows the chemical structure of the hormone, can inject its synthetic form In this case = full agonist Some = partial agonist : have some of the original hormone effects but not all of them. Sometimes…it ’s better than nothing!

11. Methods in Behavioral Neuroendocrinology 2. Hormone Replacement : Factors to consider A. Chemical Preparation: Many synthetic compounds that are supposed to do the same thing, have different chemical preparations E.g. Contraceptive pills : many forms with varying degrees of estrogen and progesterone Some chemical preparations, unwanted side-effects. These side-effects can IMPACT on The measured behavior e.g. metyrapone; nausea; behavior

12. Methods in Behavioral Neuroendocrinology 2. Hormone Replacement : Factors to consider B. Dose : The dose to be injected in order to REPLACE hormone levels to the levels they were BEFORE the ablation has to be determined Necessitate a lot of preliminary studies Of DOSE-RESPONSE experiments.

13. Methods in Behavioral Neuroendocrinology 2. Hormone Replacement : Factors to consider C. Vehicle : Depending on the TYPE of hormone we want to inject we will have to use a different vehicle PEPTIDE : Water-Soluble Will dissolve the synthetic proteine in a water solution STEROID : Lipid Soluble Will dissolve the synthetic steroid in corn or peanut oil

14. Methods in Behavioral Neuroendocrinology 2. Hormone Replacement : Factors to consider D. Route of Administration: Some hormones can be given orally, but others have to be injected Injection : subcatenous, intraveinous Intracerebral injections. Injection vs Infusion All these parameters will greately affect The timing of the replacement protocol

15. Methods in Behavioral Neuroendocrinology 2. Hormone Replacement : Factors to consider E. Timing of hormone replacement and behavioral testing: The body will try to keep homeostatis after ablation e.g. down-regulation of receptors So, if replace fast, might not have any effects acutely. Same thing for testing: if test immediately after replacement, might not see a change, due to time-course effect.

16. Hormone Replacement Protocol in Humans : Example The MR/GR Balance Theory deKloet et al., 1999 Memory Performance MR Activation GR Activation facilitation inhibition Dose of administered glucocorticoids

17. Modulatory Actions of Glucocorticoids and Memory Function in Humans COGNITION COGNITION Placebo Placebo Baseline Day Circulating Cortisol Levels Experimental Day Metyrapone Hydrocortisone

18. Experimental Day Memory Testing Metyrapone 750mg p.o. Metyrapone 750mg p.o. Memory Testing Hydrocortisone Infusion (0.06mg/kg/h) Catheter Lunch Snack Snack BS BS BS BS BS BS BS BS 1115 1145 1205 1040 1045 1200 0920 0950 0955 1030 0600 0630 0730 0800 0805 0830 0915 0900 Placebo Day Counterbalanced Within and Across Participants Memory Testing Memory Testing Placebo p.o. Placebo p.o. Placebo Infusion Catheter Lunch Snack Snack BS BS BS BS BS BS BS BS 1115 1145 1205 1040 1045 1200 0920 0950 0955 1030 0600 0630 0730 0800 0805 0830 0915 0900

20. Methods in Behavioral Neuroendocrinology 1. EXPERIMENTAL STUDIES 2 major types in behavioral neuroendocrinology A. Behavioral responses to neuroendocrine manipulations B. Neuroendocrine responses to behavioral manipulations

21. Methods in Behavioral Neuroendocrinology Methods in Behavioral Neuroendocrinology 1. EXPERIMENTAL STUDIES B. Neuroendocrine responses to behavioral manipulations In this type of experiment : IV : Manipulated Behavior DV : Measured Hormone levels Now, how can we MANIPULATE behavior?? --> By changing behaviors, social interactions etc. so, many technics….

22. Methods in Behavioral Neuroendocrinology A. Responses to ENVIRONMENTAL variations Since hormone secretion is tightly linked to the environment in which an organism lives, if modify this environment, should modify hormone levels. E.g. Different types of stressors noise, immobilization, restraint leads to different stress responses.

23. Methods in Behavioral Neuroendocrinology B. Neuroendocrine responses to Social Interactions Hormone levels can be changed in response to social interactions e.g. sexual interactions; testosterone e.g. dominant/subordinate interaction and stress hormones e.g. Children in day care vs home and stress hormone levels So, by putting the subject in different social Interactions, we might change hormone levels.

24. Methods in Behavioral Neuroendocrinology C. Neuroendocrine Reflexes: Some stimuli can trigger the release of hormones in a reflex fashion. E.g. Pheromones : prime reproductive system E.g. Vaginal Stimulation in rodent and release or prolactin and oxytocin E.g. Babies and milk secretion in mothers Can use these reflexes to induce hormonal changes

25. Methods in Behavioral Neuroendocrinology D. Neuroendocrine Responses to cognitive stimuli The way external stimuli are interpreted can trigger hormone secretion E.g. Examination Stress : Depends on the level of mastery felt by individual E.g. Depression : Negative appraisal of environment, increased cortisol secretion

26. Methods in Behavioral Neuroendocrinology E. Conditioned hormone release If a hormone has been released in a previous situation in which something aversive or negative happened, then encountering this situation again (without the negative event) will automatically induce release of the same hormone E.g. Corticosteroid release in a taste aversion task E.g. Corticosteroid release in a panic attack on a bridge.

27. Methods in Behavioral Neuroendocrinology Possible confounding variables in neuroendocrine studies A. Species Differences : Not all species (animal studies) respond the same to situations. So cannot generalize from one species to the other E.g. Different strains of rats; different responsivity to stress Creation of a rat stress model. E.g. Knowing this, scientists can create genetically different inbred strains of mice differing on a particular characteristic

28. Methods in Behavioral Neuroendocrinology Possible confounding variables in neuroendocrine studies B. Individual Differences : It is an error to think that all animals (and humans) will respond the same in response to stimulation. Important individual differences that might be DUE to hormonal variations E.g. variations in behavior and hormone in mice depending on uterine position (between 2 males, or between 2 females)...

29. Methods in Behavioral Neuroendocrinology Possible confounding variables in neuroendocrine studies C. Experiential Factors : Depending on the past experience of an individual, he/she might not respond the same to a stimulus, compared to another individual. E.g. Reared in isolation vs family Important differences in stress reactivity E.g. Dominant vs Subordinate males Important differences in testosterone

30. Methods in Behavioral Neuroendocrinology Possible confounding variables in neuroendocrine studies D. Environmental factors : Changes in the environment might impact on hormone secretion. If this is not controlled in advance, might induce confounding factors. E.g. Circadian rhythm : Stress studies E.g. Seasonal variation : mood E.g. Menstrual Cycle : mood & stress

31. Methods in Behavioral Neuroendocrinology Possible confounding variables in neuroendocrine studies E. Stimulus situation: All the characteristics related to a particular test situation might impact on hormone levels, and thus act as a confounder if not controlled for a priori. E.g. # rats per cage E.g. Gender of experimenter (pheromone) E.g. Handling before experiment E.g. Lab setting and stress reactivity E.g. Lab light and melatonin study

32. Methods in Behavioral Neuroendocrinology Possible confounding variables in neuroendocrine studies F. The present state of the subject Given that hormone levels are known to change with an individual ’s state of mind, the state of the subject has to be taken into consideration in order to avoid confound effects. E.g. PMS and stress reactivity E.g. Depression and memory E.g. Drugs and pharmacological studies

33. The Scientific Method: Are you sure?