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.
- Bladder motility
- Central activity
ASJC Scopus subject areas
- Cellular and Molecular Neuroscience