METABOLIC DISEASE 2 Flashcards
MICE B CELL ABLATION - why is it done?
Method?
Ablate B cells - B cells of the pancreas are able to regenerate.
Mechanism is not well understood.
If we could understand how/why this could present treatment for diabetes
ZEBRAFISH CHEMICAL SCREEN
Attempt to find new T2D treatment ?
Method
1) Zebrafish taken and TRANSGENIC REPORTER LINE is produced. Shows insulin expression
2) Fish treated with MTZ –> catalyses production of a toxic compound. This causes apoptosis in B cells specifically
3) Add compounds from library to the embryos in the well plate - are any seen to have rescue effect on the B cells?
4) Leave for a couple of days and quantify the regeneration of the B cells using DOUBLE-TRANSGENIC LINE
What is the TARGET of rescue compounds identified in the zebrafish screen?
What does this allow us to conclude?
Targets - phosphodiesterases, adenosineRs, adenosine kinases ——-> adenosine selective agonists INCREASE B CELL REGENERATION
What are the 2 body/brain pathways that could be compromised to result in abnormal metabolic signalling?
Abnormal signalling between tissues of the body and the brain
Abnormal signalling between the brain and tissues of the body (liver, pancreas and adipose tissue)
What is Leptin?
Hormone secreted by ADIPOCYTES (fat cells) –> signals the brain regarding the body’s energy content
What was shown in mice that were leptin deficient?
Obese, diabetic, hypoactive, infertility
How does leptin work – what does it target? How was this shown in mice?
Leptin directly impacts neurons - in mice conditional K.O of LepRs was carried out on cells of the liver - the phenotype of the mouse overall was okay but the BRAIN exhibited obese phenotype
Where are Leptin receptors found?
ARCUATE NUCLEUS of the HYPOTHALAMUS
Types of Neuron in the Arcuate nucleus
2 types of neuron that have antagonistic effects
NpY neurons - cause increase in food take
Pomc neurons - LABRADORS MUTATED - caused decrease in food intake
How does the brain control the effects of Leptin and how was this shown?
Brain mediates Leptin’s action on homeostasis
DELETION LEPRs - induces obesity
Mice lacking leptin - obese/diabetic/infertile/hypoactive
Intracerebroventricular administration of leptin caused reduction in food intake and body weight
How was it discovered that Leptin binds to primary receptors in the Hypothalamus?
CONDITIONAL KO
Flox allele that codes for leptin in every cell
Breed with mouse with cre inserted downstream of a hypothalamic promoter — knocks out LepRs in hypothalamus ONLY
LEPTIN/HYPOTHALAMUS CASCADE???
Adipose tissue —secretes leptin–> Arcuate Nucleus of the Hypothalamus —-> Brainstem –via vagus nerve—> Liver
