Revision- Neurotransmitter, agonist/ antagonist/ excitatory/ inhibitory Flashcards
combination of studies for neurotransmitter
Meyer et al. and Andersen et al.
Agonist and antagonist
Agonist: a chemical that binds to the receptor site of the neuron and increases the neurotransmitter action. Prozac is an agonist drug that increases serotonin at synapses.
Agonist may:
1) Enhance a neuron’s ability to synthesize, store or release neurotransmitters.
2) Mimic the action of the transmitter by binding with and stimulating postsynaptic receptor sites
4) Makes it more difficult to be deactivated, such as by inhibiting reuptake.
Antagonist: a chemical that binds to the receptor site of the neuron and decreases the neurotransmitter action at the postsynaptic neuron.
Antagonist may:
1) reduce a neuron’s ability to synthesize, store or release neurotransmitters
2) bind their receptors and block the normal action of the transmitters.
excitatory and inhibitory
Excitatory: these types of neurotransmitters increase the likelihood that the neuron will fire an action potential. It is also when a drug attaches to a receptor site for a neuron and activates the neuron as if the neurotransmitter was sending a message.
Inhibitory: when a neurotransmitter decreases the likelihood that the neuron will fire an action potential. It may also be when a drug attaches to a receptor site for a neurotransmitter and blocks the transmission across the synapse.
difference between agonist and excitatory
An excitatory neurotransmitter will have its excitatory effect increased by an agonist but decreased by an antagonist.
difference between antagonist and inhibitory
An irreversible antagonist binds covalently and cannot be displaced by either competing ligands or washing. Inhibitors are drugs that can bind to a protein, such as an enzyme and decrease its activity.
Study for both antagonist and agonist
Kraehenmann et al.
Study for both antagonist/agonist and excitatory/inhibitory
Kraehenmann et al.
Kraehenmann et al study
Dreamlike effects of LDS on waking imagery in humans depend on serotonin 2A receptor activation.
Aim: to test the hypothesis that LDS produces dreamlike walking imagery, and that this imagery depends on 5-HT2A receptor activation and is related to subjective drug effects.
Procedure: pps performed an audio-recorded guided mental imagery task 7 hours after drug administration during thee drug condition: placebo, LSD (100 mcg orally) and LSD together with the 5-HT2A receptor antagonist ketanserin (40 mg orally). Cognitive bizarreness of guided mental imagery reports was quantified as a standardized formal measure of dream mentation. State of consciousness was evaluated using Altered State of Consciousness (5D-ASC) questionnaire.
Results: LSD, compare with placebo, significantly increased cognitive bizarrness. The LSD-induced increase in cognitive bizarreness was positively correlated with the LSD induced loss of self-boundaries and cognitive control. Both LSD-induced increases in cognitive bizarreness and change in state of consciousness were fully blocked by ketanserin (5-HT2A receptor antagonist).
Meyer et al study
Meyer et al (2006) Elevated Monoamine Oxidase-A levels in the brain.
aim: to investigate whether MAO-A levels (an enzyme that breaks down the neurotransmitters in the synapse) are elevated during untreated depression.
pps: 17 healthy and 17 depressed with major depressive disorder. depressed pps had been medication-free for at least 5 months.
procedure: PET to measure amount of MAO-A. pps is injected with a harmless dose of radioactive glucose. the scans produce a colored map of brain activity.
results: MAO-A was highly significantly elevated in every brain region assessed. The MAO-A was elevated on average by 34% (2 SDs) throughout the brain during major depression.
Andersen et al study
Effective Treatment of Poststroke Depression With the Selective Serotonin Reuptake Inhibitor (SSRI) Citalopram.
Aim: the study was designed to investigate the efficacy and safety of SSRI citalopram in treating poststroke depression.
Pps: depressed stroke ppl
Procedure: pps were assigned to equally sized treatment and placebo groups. A 6-week double-blind, placebo-controlled was undertaken. In a placebo-controlled trial, one group is given a real treatment and another an inert substance. When a double-blind technique is used neither the pps nor researcher know who is in which condition. The Hamilton Depression Scale was used to measure the amount of depression. The UKU side effect rating scale was used to measure unwanted side effects. The initial depression levels was comparable in the two groups (mean baseline Hamilton Depression scores, 19.4 and 18.9 respectively). Demographic parameters were also comparable in the two groups.
Results: Significantly greater improvement was seen in patients treated with citalopram ( 10 to 40 mg/d) for 3 and 6 weeks. The difference was larger when patients who dropped out were excluded. Half of the 28 patients who entered the trial 2 to 6 weeks after stroke recovered within 1 month, independent of the treatment given.
LSD
inhibitory
- it is an agonist and its effect at an excitatory synapse influences behavior cognitive bizarreness.
- sends the negative response and no action potential. inhibitory needs agonist.
Hormones and Behaviour
it can be asked about explain the effect of one hormone and can also be the function of one hormone. explain: reasons and causes. Andersen doesn’t show how synapses….. think also abt research method possibilities .
how to answer this question: “Explain the effect/function of one hormone on human behaviour”
-identify a hormone
-identify behavior
-define and describe where produced
explain How this leads to this behaviour/ function. Why?
if I use testosterone- Androgen receptors are abundant prefrontal brain regions (involved in reflective cognition), specifically, an area called the ventral medial prefrontal cortex (VMPFC)- decision making (Nave et al.)
thus, a plausible neural mechanism underlying the behavioural effect is Testosterone-induced inhibition of prefrontal activation.
(I can use nave and renee studies)
challenging hypothesis
when we are challenged we need to face this challenge. The challenge hypothesis outlines the dynamic relationship between testosterone and aggression in mating contexts. It proposes that testosterone promotes aggression when it would be beneficial for reproduction, such as mate guarding, or strategies designed to prevent the encroachment of intrasexual rivals.
Pheromones and behavior
what concepts/ need to know?
- definition
- where produced (found) and released, how communicated?
- putative pheromones
- Androstadinone (AND)
- Estratetraneol (EST)
Critical thinking?:
- Do pheromones play a role in human behaviour? arguments for and against!
- definition: not agreed upon
- location: the presence of VNOs in humans is debatable, with evidence on both sides, function debatable.
- quality of empirical evidence: methodology (demand characteristics, ecological validtiry)
- behaviour/ pheromone construct validity
- theoretical evidence: evolution;sexual maturity
- animal models
- reductionist
- smell is complex
- contradictory findings
- financial interests
