Endorphins and the central inhibition of urinary bladder motility |
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Authors: | A Dray R Metsch TP Davis |
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Institution: | Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA |
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Abstract: | The involvement of endogenous opioid mechanisms in the central neurogenic control of urinary bladder function has been examined in anesthetized rats. Intracerebroventricular (ICV) microinjection of β-endorphin (0.5–2.0 μg) produced powerful inhibition of rhythmic bladder contractions initiated by central reflex activity. The peptide fragments γ-endorphin and α-endorphin (4–16 μg), formed by the processing of β-endorphin by membrane homogenates of brain, were less active than the parent compound. The inhibitory effects of β-endorphin was reversed by ICV naloxone (1–2 μg) but higher doses were required to reverse γ- or α-endorphin effects. ICV naloxone administered alone increased intravesicular pressure and bladder contraction frequency. These observations support the hypothesis that the endorphins have a physiological role in the central regulation of urinary bladder activity. |
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Keywords: | Endorphins Central activity Bladder motility |
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