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Full-Text Articles in Pharmacology, Toxicology and Environmental Health
Signaling Mechanisms For Muscarinic Receptor-Mediated Coronary Vasoconstriction In Isolated Rat Hearts, Yi Zhang
Electronic Theses and Dissertations
The signaling mechanisms for muscarinic receptor-mediated vasoconstriction in coronary resistance arteries were studied in KCl-arrested isolated rat hearts perfused at a constant flow rate. The cholinergic agonists acetylcholine and bethanechol were given by bolus injection or constant infusion. The coronary vascular resistance was monitored by measuring the changes in perfusion pressure. The selective muscarinic agonist bethanechol caused a similar vasoconstrictor response as ACh, but with less potency and efficacy. Bolus injection of bethanechol evoked a phasic vasoconstriction in a dose-dependent manner, while infusion of bethanechol evoked a tonic vasoconstriction without producing tachyphylaxis. Coronary vascular responses to bethanechol were further examined …
Mouse Embryo Development In The Presence Of Capsaicin, Carlos Santiago Villar-Gosalvez
Mouse Embryo Development In The Presence Of Capsaicin, Carlos Santiago Villar-Gosalvez
Theses and Dissertations in Biomedical Sciences
Capsaicin is the pungent agent found in hot peppers of the Capsicum genus. It is a potent neurotoxin that stimulates the degranulation and degeneration of C-afferent neurons. Capsaicin is widely used as a food condiment and medicine. Human exposure of capsaicin can exceed levels shown to be neurotoxic in laboratory animals. Additionally, capsaicin can cross the blood/placenta barrier and affect an embryo in utero. In order to assay the potential for toxicity to human embryos, mouse embryos were exposed to capsaicin and the effect of the capsaicin on embryo development was measured. Embryos were co-cultured in Krebs medium with 1% …
Lead Activation Of A Developmentally Regulated Calcium Channel In Rat Hippocampal Nerve Terminals, Troy E. Rhodes
Lead Activation Of A Developmentally Regulated Calcium Channel In Rat Hippocampal Nerve Terminals, Troy E. Rhodes
Theses and Dissertations in Biomedical Sciences
Low level lead (Pb2+) exposure may produce lasting deficits in learning and memory by altering calcium (Ca2+) dependent processes. Isolated presynaptic nerve terminals from rat hippocampus were loaded with the intracellular (Ca2+) indicator Fura-2. The changes in cytoplasmic free calcium ([Ca2+]i) were measured by stopped-flow fluorescence spectroscopy following depolarization with elevated potassium on a millisecond time scale (Lentzner et al., 1992). Depolarization promoted a rapid increase in Ca2+i which occured in two kinetically distinguishable phases: a fast component, representing the activity of rapidly inactivating Ca2+ channels (τ …
Persistent Oral Dyskinesias Induced By Long-Term Haloperidol Treatment Is Dissociated From Changes In Neostriatal B(Max) And Mrna Content For Dopamine D(2) Receptors, Nuoyu Huang
Electronic Theses and Dissertations
Due to the presumed associations of dopamine (DA) receptor supersensitivity phenomena in both long-term neuroleptic-treated tardive dyskinetic rats and neonatal 6-hydroxydopamine (n6-OHDA)-lesioned rats, we studied the influence of haloperidol on n6-OHDA-lesioned rats. At 3 days after birth rats received 6-OHDA-HBr (200 $\mu$g, bilateral intracerebroventricularly; desipramine pretreatment, 20 mg/kg, 1h) or vehicle. Two months later haloperidol (1.5/kg/day $\times$ 2 days/week for 4 weeks, then 1.5 mg/kg/day, every day for 10 months) was added to the drinking water. Spontaneous oral activity of intact and n6-OHDA-lesioned rats receiving haloperidol was reached and maintained at significantly higher levels after 15 weeks of haloperidol treatment. …
Co-Sensitization Of Dopamine And Serotonin Receptors Occurs In The Absence Of A Change In The Dopamine D1 Receptor Complex After A Neonatal 6-Ohda Lesion, Li Gong
Electronic Theses and Dissertations
To test whether SKF 38393 could ontogenetically sensitize dopamine (DA) D$\sb1$ receptors and whether this sensitization would be associated with biochemical changes, intact and neonatal 6-hydroxydopamine (6-OHDA)-lesioned rats (200 $\mu$g i.c.v.) were treated daily from birth with SKF 38393 (3.0 mg/kg i.p. x 28 days) or its vehicle. In DA D$\sb1$ neonatally sensitized 6-OHDA rats, enhanced locomotor responses were observed with the first SKF 38393 challenge dose (3.0 mg/kg i.p.) at 6 weeks. This response increased further with weekly SKF 38393 treatments. Enhanced stereotyped behaviors were seen in both lesioned and sensitized rats at 8 weeks. There was no change …
The Effect Of Trimethyltin On The Cholinergic System Of The Rat Hippocampus, Richard L. Cannon
The Effect Of Trimethyltin On The Cholinergic System Of The Rat Hippocampus, Richard L. Cannon
Electronic Theses and Dissertations
Trimethyltin (TMT) is a neurotoxin occurring in the environment. Exposure to (TMT) is known to destroy specific neuronal components of the hippocampus in the rat and to cause clinical symptoms in exposed humans, including mnemonic deficits, that indicate hippocampal involvement. In addition to hippocampal cell loss TMT causes significant increases in cholinergic markers such as acetylcholinesterase (AChE) stain density and choline acetyltransferase (ChAT) activity in the hippocampus of rats. However, despite these observations the effect of TMT on hippocampal cholinergic system has not been investigated in detail. The purpose of the present study was to elucidate more fully the consequences …
Identification And Characterization Of Possible Multiple Binding Sites For ((3)H)8-Oh-Dpat In The Hippocampus, Dawna Lea Evans
Identification And Characterization Of Possible Multiple Binding Sites For ((3)H)8-Oh-Dpat In The Hippocampus, Dawna Lea Evans
Masters Theses
No abstract provided.
Fixed-Ratio Size As A Determinant Of The Development Of Tolerance To Morphine, Mark J. Nickel
Fixed-Ratio Size As A Determinant Of The Development Of Tolerance To Morphine, Mark J. Nickel
Masters Theses
The acute and chronic effects of morphine were examined in pigeons exposed to a multiple schedule with fixed ratio 5, 25, and 125 components. Acute exposure to morphine (0.56-10.0 mg/kg) resulted in rate reductions under each component when the dose was 1 mg/kg or higher. With chronic exposure to 5.6 mg/kg, tolerance to the rate-reducing effects of morphine was evident under each fixed ratio component. The development of tolerance was determined to some extent by fixed-ratio size, a result similar to earlier findings with cocaine.