Animal Models - Genetics - cases + mosienko

MAOA

• produces enzyme MAOA (e-MAOA), which breaks down neurotransmitters like serotonin

• these neurotransmitters regulate impulse control and emotional responses

• MAOA-L have lower levels of MAOA, leading to a reduction in serotonin breakdown

• during prenatal development, MAOA-L gene results in overexposure of brain to high serotonin levels which could cause the brain to be less receptive to serotonin in the future

• which could impair emotional regulation and increase potential for aggression

animal models

• used in research to understand humans without risk of causing harm to a human during the process, however there are still some ethical considerations that must be followed even with animal studies

animal models eval

Strengths

• Allows for a longitudinal study across whole lifespan

• Can rigorously control environment allowing for less extranious variables

• Human study to support - meyer lindenberg

Limitation

• Animals are different to humans in their cognitive levels meaning the results might not be generalised to the human population

meyer-lindenberg study of support

• aimed to investigate how MAOA-L affects brain function

• found that MAOA-L condition had significant increase of activity in amygdala and reduced activity in PFC

• these results demonstrate a clear link between MAOA-L and increased aggression

cases aim

• to investigate the genetic origins of aggression in mice

cases method

• erased MAOA in mice and observed their actions

• resident intruder paradigm was used where mouse placed inside cage of another mouse

• also conducted an autopsy of the brain after observations

cases results

• adult mice showed signs of aggressive behaviour like biting researcher

• in intruder paradigm, mice without MAOA adopted a threatening stance when other mouse introduced and would exhibit aggressive behaviour while control would just sniff other mouse

• brains of mice without MAOA had an increase in serotonin of 9 times higher than controls

cases conclusion

• in conclusion, mice without MAOA showed more signs of aggression because they were more aggressive to intruders compared to mice with MAOA

TPH-2 knockout gene

• converts tryptophan into serotonin

• sends info to nucleus to begin process of conversion

• if gene is deleted or reduced then that will reduce the serotonin levels in the brain

• examined through animals where TPH-2 is knocked out (deleted)

Mosienko aim

• to investigate how knocking out TPH-2 would affect mice

mosienko method

• compared genetically modified mice with TPH-2 knocked out with control group

• resident intruder test done

mosienko results

• TPH-2 mice attacked 6 times faster than the control group when meeting the intruder

• more TPH-2 knockout mice attacked intruder compared to normal mice

mosienko conclusion

in conclusion, TPH-2 knockout caused mice to become more aggressive compared to mice with TPH-2 still intact because the TPH-2 knockout mice attacked 6 times quicker than control group and conducted more attacks overall