title: Histological studies of the effects of chronic implantation of ceramic-based microelectrode arrays and microdialysis probes in rat prefrontal cortex.
abstract: Chronic implantation of neurotransmitter measuring devices is essential for awake, behavioral studies occurring over multiple days. Little is known regarding the effects of long term implantation on surrounding brain parenchyma and the resulting alterations in the functional properties of this tissue. We examined the extent of tissue damage produced by chronic implantation of either ceramic microelectrode arrays (MEAs) or microdialysis probes. Histological studies were carried out on fixed tissues using stains for neurons (cresyl violet), astrocytes (GFAP), microglia (Iba1), glutamatergic nerve fibers (VGLUT1), and the blood-brain barrier (SMI-71). Nissl staining showed pronounced tissue body loss with microdialysis implants compared to MEAs. The MEAs produced mild gliosis extending 50-100 microm from the tracks, with a significant change in the affected areas starting at 3 days. By contrast, the microdialysis probes produced gliosis extending 200-300 microm from the track, which was significant at 3 and 7 days. Markers for microglia and glutamatergic fibers supported that the MEAs produce minimal damage with significant changes occurring only at 3 and 7 days that return to control levels by 1 month. SMI-71 staining supported the integrity of the blood-brain barrier out to 1 week for both the microdialysis probes and the MEAs. This data support that the ceramic MEA's small size and biocompatibility are necessary to accurately measure neurotransmitter levels in the intact brain. The minimal invasiveness of the MEAs reduce tissue loss, allowing for long term (>6 month) electrochemical and electrophysiological monitoring of brain activity.
authors: Anatomy and Neurobiology, Morris K. Udall Parkinson's Disease Research Center of Excellence, Center for Microelectrode Technology, University of Kentucky, College of Medicine, Lexington, KY, 40536-0098 USA. erinhascup@gmail.com
authors: Erin R
authors: ER
authors: Hascup
authors: Sara
authors: S
authors: af Bjerkén
authors: Kevin N
authors: KN
authors: Hascup
authors: Francois
authors: F
authors: Pomerleau
authors: Peter
authors: P
authors: Huettl
authors: Ingrid
authors: I
authors: Strömberg
authors: Greg A
authors: GA
authors: Gerhardt
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001253:Astrocytes / Q000378:metabolism / Q000473:pathology; D001812:Blood-Brain Barrier / Q000378:metabolism / Q000473:pathology; D004567:Electrodes, Implanted / Q000009:adverse effects*; D018698:Glutamic Acid / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D017551:Microdialysis / Q000009:adverse effects*; D008839:Microelectrodes; D017628:Microglia / Q000378:metabolism / Q000473:pathology; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D017397:Prefrontal Cortex / Q000378:metabolism* / Q000473:pathology*; D051381:Rats; D020318:Rats, Long-Evans
chemical_list: D018698:Glutamic Acid