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Adult Guinea Pigs (adult + guinea_pigs)

Distribution by Scientific Domains
Medical Sciences100%

Selected Abstracts

Short-Term Antiandrogen Flutamide Treatment Causes Structural Alterations in Somatic Cells Associated with Premature Detachment of Spermatids in the Testis of Pubertal and Adult Guinea Pigs

REPRODUCTION IN DOMESTIC ANIMALS, Issue 3 2010
LR Maschio
Contents In spite of widespread application of flutamide in the endocrine therapies of young and adult patients, the side effects of this antiandrogen on spermatogenesis and germ-cell morphology remain unclear. This study evaluates the short-term androgen blockage effect induced by the administration of flutamide to the testes of pubertal (30-day old) and adult (65- and 135-day old) guinea pigs, with an emphasis on ultrastructural alterations of main cell types. The testes removed after 10 days of treatment with either a non-steroidal antiandrogen, flutamide (10 mg/kg of body weight) or a pharmacological vehicle alone were processed for histological, quantitative and ultrastructural analysis. In pubertal animals, flutamide androgenic blockage induces spermatogonial differentiation and accelerates testes maturation, causing degeneration and detachment of primary spermatocytes and round spermatids, which are subsequently found in great quantities in the epididymis caput. In post-pubertal and adult guinea pigs, in addition to causing germ-cell degeneration, especially in primary spermatocytes, and leading to the premature detachment of spherical spermatids, the antiandrogen treatment increased the relative volume of Leydig cells. In addition, ultrastructural evaluation indicated that irrespective of age antiandrogen treatment causes an increase in frequency of organelles involved with steroid hormone synthesis in the Leydig cells and a dramatic accumulation of myelin figures in their cytoplasm and, to a larger degree, in Sertoli cells. In conclusion, the transient exposition of the guinea pigs to flutamide, at all postnatal ages causes some degenerative lesions including severe premature detachment of spermatids and accumulation of myelin bodies in Leydig and Sertoli cells, compromising, at least temporarily, the spermatogenesis. [source]

Selective Vestibular Ablation by KTP Laser in Endolymphatic Hydrops,,

THE LARYNGOSCOPE, Issue 6 2001
Melanie Adamczyk MD
Abstract Objectives and Hypothesis Vertigo, the cause of disability in many patients with Ménière's disease, may be the result of the effects of endolymphatic hydrops on the semicircular canals. We hypothesize that intractable vertigo may be controlled by destruction of the semicircular canal neuroepithelium using visible light lasers without the need for extensive fenestration of the bony labyrinth. This study was designed to assess the cochlear effects of potassium titanyl phosphate (KTP) laser-assisted triple semicircular canal ablation (TSCA) in endolymphatic hydrops. Study Design Randomized, prospective, and controlled. Methods Forty-one adult guinea pigs underwent either a unilateral endolymphatic duct occlusion to induce hydrops or a sham procedure. Ten weeks after induction of the hydrops, a KTP laser-assisted TSCA or a sham surgery was performed. Results Electrocochleographic thresholds to clicks and tone-bursts (2,20 kHz) did not change significantly up to 4 weeks after TSCA in hydropic ears. Cross-sectional histology confirmed the presence of hydrops and the ablation of the semicircular canals. Cochlear whole-mounts for hair cell counts showed no significant loss of outer or inner hair cells in hydropic ears treated with TSCA. Conclusion KTP laser-assisted TSCA can be performed in the guinea pig model of endolymphatic hydrops without significant loss of hearing. Evaluation of this technique may be warranted in patients with intractable Ménière's disease. [source]

Emodin Inhibits Voltage-Dependent Potassium Current in Guinea Pig Gallbladder Smooth Muscle

BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 3 2009
Zhi-Xuan Wu
We studied the effects of emodin on the contraction of gallbladder smooth muscle and voltage-dependent K+ current in gallbladder smooth muscle cells. Gallbladder muscle strips were obtained from adult guinea pigs and the resting tension was recorded. Gallbladder smooth muscle cells were isolated by enzymatic digestion, and K+ current was recorded by the whole-cell patch clamp method. Emodin increased the resting tension of gallbladder smooth muscle strips and inhibited voltage-dependent K+ current in a dose-dependent manner. When 10 µM emodin was applied to gallbladder smooth muscle cells for 3,6 min., the amplitude of voltage-dependent K+ current was decreased by 31.5 ± 0.5% at +40 mV, and this inhibitory effect mostly recovered after washout. The steady-state inactivation curves were shifted in a hyperpolarizing direction by emodin. In the presence of the protein kinase C inhibitors staurosporine and chelerythrine, the effect of emodin on voltage-dependent K+ current was significantly attenuated. In conclusion, emodin promotes gallbladder contraction, mainly by inhibiting voltage-dependent K+ current via the protein kinase C pathway. These findings provide theoretical foundation for the application of emodin in gallbladder motility disorders. [source]