Greg A. Gerhardt

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Parkinson's disease results from the progressive degeneration of dopamine neurons that innervate the striatum. In rodents, glial-cell-line-derived neurotrophic factor (GDNF) stimulates an increase in midbrain dopamine levels, protects dopamine neurons from some neurotoxins, and maintains injured dopamine neurons. Here we extend the rodent studies to an(More)
Recently, a novel glial cell line-derived neurotrophic factor (GDNF) has been identified, cloned, and shown to have potent survival- and growth-promoting activity on fetal rat midbrain dopaminergic neurons in cell culture. In this study, we document marked and long-lasting effects on adult rat midbrain dopaminergic neurons in vivo after intracranial(More)
Locomotor activity is a polygenic trait that varies widely among inbred strains of mice (). To characterize the role of D2 dopamine receptors in locomotion, we generated F2 hybrid (129/Sv x C57BL/6) D2 dopamine receptor (D2R)-deficient mice by gene targeting and investigated the contribution of genetic background to open-field activity and rotarod(More)
In the unilateral 6-hydroxydopamine (6-OHDA)-lesioned rat model of Parkinson's disease, controversy exists concerning the use of apomorphine- or D-amphetamine-induced rotations as reliable indicators of nigrostriatal dopamine depletion. Our objective was to evaluate which, if either, drug-induced behavior is more predictive of the extent of nigrostriatal(More)
A self-referencing technique utilizing two microelectrodes on a ceramic-based multisite array is employed for confirmation and elimination of interferences detected by enzyme-based microelectrodes. The measurement of L-glutamate using glutamate oxidase was the test system; however, other oxidase enzymes such as glucose oxidase can be employed. One recording(More)
To investigate functional changes in the brain serotonin transporter (SERT) after chronic antidepressant treatment, several techniques were used to assess SERT activity, density, or its mRNA content. Rats were treated by osmotic minipump for 21 d with the selective serotonin reuptake inhibitors (SSRIs) paroxetine or sertraline, the selective norepinephrine(More)
This paper describes the development and characterization of ceramic-based multisite arrays for electrochemical recordings in biological systems. These electrodes represent a parallel technology to the design of microelectrodes using silicon substrates. The ceramic substrates are stronger than silicon and are nonconducting, which makes them better suited(More)
In vivo electrochemistry was used to determine the effects of locally applied raclopride (a D2 receptor antagonist) and SCH-23390 (a D1 receptor antagonist) on the clearance of locally applied dopamine in the striatum, nucleus accumbens, and medial prefrontal cortex of rats. Chronoamperometric recordings were continuously made at 5 Hz using Nafion-coated,(More)
L-glutamate (Glu) is the predominant excitatory neurotransmitter in the mammalian central nervous system. It plays major roles in normal neurophysiology and many brain disorders by binding to membrane-bound Glu receptors. To overcome the spatial and temporal limitations encountered in previous in vivo extracellular Glu studies, we employed enzyme-coated(More)
Fischer 344 rats were unilaterally injected into the medial forebrain bundle with 6-hydroxydopamine (6-OHDA). Apomorphine-induced rotational behavior was used to select animals whose rotation exceeded 300 turns/h, corresponding to greater than 95% dopamine (DA) depletion in the ipsilateral striatum. Four weeks later, glial cell line-derived neurotrophic(More)