Lecture 9 - Manipulation of endocrine function Flashcards
Discuss the advantages and disadvantages of different methods for delivering hormones.
Feed additives Advantages - Works for small molecules Disadvantages - Not good for protein – digested - Potential contamination of equipment
Single or multiple injection Advantages - Bypasses digestive system - Gives a burst of hormone (in one shot) - Can use ultiple injections to mimic physiological levels
Sustained release devices
Advantages
- Ideal for long lasting hormone treatment
- Less time consuming than multiple injections
Disadvantages
- Dose can be a problem – super-optimal can desensitize system
- Formation of abscesses, infections, immune response
- Stability, solubility of hormone?
- Many hormones need to be pulsatile to have a biological effect (implant delivers continuous hormone)
Describe potential approaches to produce pulsatile hormone release from implants.
Mechanical pump
- Electric pump strapped on patient and connected to IV
Eroding systems
- Bulk eroding
Surface eroding
- Multiple layer of surface polymer
Osmotic device
- Surface layer made of 2 layers
- Water soluble polymer
- Water soluble pore former
- Ratio insoluble to soluble dictates rupture time
Describe the potential use of encapsulated cells for hormone replacement
“Living implant”
- immune cells can’t get in but nutrients can
Outline the method and application of immunoneutralization of hormones.
Active immunization
- Immunizae animal against hormone (using hormone as antigen)
- Ab produced by animal will block endogenous hormone production
- Works great if animal responds to antigen and produces antibody
Passive Immunization
- Infuse purified Ab against hormone into animal
- Use Ab that binds the receptor to block hormone action -
Problems
- Removal of negative feedback = increase in hormone secretion
- Immune response isn’t always effective
- Transfer of immunoglobulins to offsprings via eggs, colostrum, placenta
Discuss the use of anti-idiotypic antibodies to mimic hormone action.
Idiotype = part of an antibody that recognizes hormone
Anti-idiotypic antibodies
- Production of secondary antibodies directed against primary antibodies to a hormone will produce some antibodies that are specific for the idiotypic region
- These can have hormonal activity
Disadvantages
- Must first generate, test, purify primary Ab
- Anti-idiotypic Ab may not have hormonal activity
How are transgenic animals made and how can they be used to affect endocrine function.
Produced by inserting new gene(s) or by modifying the expression of existing gene – gene knockouts can be made by interrupting the expression of particular genes
- New genes can be used to modify hormone function to
1. Improve growth
2. Improve heath
3. Improve productivity - Can be ussed as model systems to study hormone fuction