2006 merck/merial - School of Veterinary Medicine - Louisiana State ...

Rotenone Induced Dopamine Neuron Degeneration in Nurr1-null Heterozygous and Wild-type MiceSabrina D. Hoffman*, Timothy W. Brown, and Jeffrey B. EellsCollege of Veterinary Medicine, Mississippi State University, Mississippi State, MSParkinson’s disease is the 2 nd most common neurodegenerative disease effecting 1-2% of the population over 65years of age. The hallmark of Parkinson’s disease is selective nigrostriatal dopaminergic degeneration that is believed to becaused by a combination of environmental and genetic factors. One environmental factor implicated in Parkinson’s disease isexposure to pesticides. A genetic factor may be the nuclear receptor Nurr1 as mutations in Nurr1 have been implicated inParkinson’s disease and dopamine neurons in Nurr1-null heterozygous (+/-) mice are more susceptible to certain neurotoxins.The mechanism(s) for this increased susceptibility, however, has not been determined. Chronic exposure to the pesticiderotenone has been found to reproduce many features of Parkinson’s disease in rodents. Rotenone is a common organicpesticide and acts as a complex I inhibitor of the mitochondrial respiratory chain. The purpose of the current experiment wasto determine if the +/- genotype makes dopamine neurons more susceptible to the neurotoxic affects of rotenone than wildtypemice. In this experiment a subcutaneous osmotic pump was implanted into 26 male mice for 7 days. The subjects weresplit into two groups according to their genotype. Half of the subjects for each genotype received a pump containing rotenone(6-8 mg/kg/day), and the other half received a vehicle (containing a 1:1 ratio of DMSO and PEG). Motor function tests wereperformed on all of the mice before and after the rotenone treatment using a Rota-Rod treadmill. On day 7, the mice weresacrificed and their brains excised. Immunohistochemistry was used to determine the number of dopamine neurons, andHPLC with electrochemical detection was used to determine striatal dopamine levels. The results will be calculated and thencompared across each genotype and treatment. This data is expected to help elucidate how a genetic predisposition incombination with pesticide exposure could contribute to the development of Parkinson’s disease.In Vitro Percutaneous Absorption of Phenylbutazone Through Horse SkinJones, K*; Duran, S.H.; Babu, R.J.; Ravis, W.R.; Lin, Y-JDepartment of Large Animal Surgery and Medicine; Department of Pharmacalogical Sciences, AuburnUniversity, AL 36849Phenylbutazone, a NSAID, is very effective in horses for the treatment of laminitis. However, there are many sideeffects from systemic delivery of this medication, primarily gastric ulceration and liver disease. Transdermal delivery mayprevent many of these undesirable side effects.Due to barrier properties of stratum cornuem many of the drug molecules permeate poorly across the skin.Penetration enhancers may allow increased permeation of drugs across the skin. In this study we have used carbomer gelbases containing different concentrations of alkyl urea and oleic acid as penetration enhancers.An in-vitro study was performed utilizing excised equine skin from thigh region. The skin was dermatomed to 0.6mm thick and frozen at -20oC until use. The skin was defrosted and mounted on six receptor cells of a Franz diffusion celldevice. A phosphate buffered solution (pH 7.4) with polyethylene glycol 400 at an 8:2 ratio was considered to serve as amodel for equine blood in each receptor cell. Topical gels were prepared by incorporating 1%, 2% and 3% phenylbutazonein the gel formulations of either 2% or 4% alkyl urea and 5% oleic acid. Serial samples from the receptor cells were takenover 24 hours and stored at -20oC until analyzed by a validated HPLC method with a recovery of 99%. The cumulatedamount of phenylbutazone permeated was plotted as a function of time. Even though the concentration of phenylbutazone inthe formulation E4 was 3 times less than the formulation E3, it produced similar permeation rate, demonstrating that the alkylurea provides potent permeation enhancement for phenylbutazone. It appears we may have to increase the alkyl ureaconcentration beyond 4% concentration in the formulation for better permeation enhancement rate.Immunochemical detection of three proteins expressed in the canine olfactory mucosaE. A. Lantz*, J. C. Dennis, E. E. MorrisonAnatomy, Physiology, Pharmacology; Auburn University College of Veterinary MedicineDogs are renowned for their olfactory sensitivity and humans use detector dogs for tasks like crime prevention andsearch and rescue. The dog’s have important value as biosensors, however, little is known about how the biology of thecanine main olfactory sensory epithelium (OE) compares to other mammals and, in particular to that of the rat, the beststudied mammalian species. Sensory neurons in the adult rat OE are produced throughout the individual’s life and duringmaturation, sequentially express growth associated protein 43 (GAP43), type III (neuron-specific) beta tubulin (BT), andolfactory marker protein (OMP). GAP43, a 43 kD polypeptide, is expressed by neurons extending axons. The 50 kD BT isexpressed by terminally differentiated neurons located in the basal sensory neuron layer. After maturation, BT expression islimited apically to the dendrites and axons distally to the olfactory bulb glomerular layer. OMP is a 19 kD protein ofuncertain function. It is expressed throughout the mature olfactory sensory neuron. We used immunohistochemistry toinvestigate, in adult male and female hounds, the expression patterns of these three proteins. Specificity of antibody bindingon tissue sections was confirmed by western blotting of ethmoturbinate tissue homogenates. Cell bodies in the basalcompartment are BT(+). Apically, cell bodies are BT(-)/OMP(+). GAP43 is expressed in the OE in patches suggesting138