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Microdialysis: a system for localized drug delivery into the brain
1Department of Physiology and Biophysics, University of Tennessee, Memphis 38163.
Brain Research Bulletin
|April 1, 1989
Summary
Intrahypothalamic microinjections can cause temperature rises due to tissue injury and prostaglandins. Microdialysis avoids this, making it preferable for intracerebral drug studies.
Area of Science:
- Neuroscience
- Physiology
Background:
- Intracerebral microinjections are common for drug delivery to the brain.
- Pyrogen-free saline (PFS) microinjections into the preoptic-anterior hypothalamus (POA) can unexpectedly increase core body temperature (Tco).
Purpose of the Study:
- To investigate the mechanisms behind Tco rises induced by PFS microinjections in the POA.
- To compare the effects of microinjection versus microdialysis for intracerebral substance administration.
Main Methods:
- Guinea pigs underwent bilateral POA cannula implantation for microinjection studies.
- Animals received either no injection, PFS microinjection, or PFS after indomethacin treatment.
- Unilateral POA cannula implantation was used for microdialysis experiments with PFS or prostaglandin E2 (PGE2).
Main Results:
- Injector insertion alone caused a Tco rise, which was amplified by PFS microinjection.
- Indomethacin pretreatment blocked the Tco increases associated with microinjection.
- PFS microdialysis did not alter Tco, while PGE2 perfusion induced a significant Tco rise.
Conclusions:
- The Tco rise from PFS microinjection is mediated by prostaglandins released due to tissue injury.
- Microdialysis is a superior method to microinjection for intracerebral administration, as it avoids confounding temperature effects.