Central cholinergic mechanisms in L-DOPA induced hyperactive urinary bladder of the rat

The involvement of central and peripheral cholinergic structures in the mediation of a centrally induced hyperactive urinary bladder response to L-2,3-dihydroxyphenylalanine (L-DOPA), after peripheral decarboxylase inhibition, registered by a cystometric procedure, has been analysed pharmacologically in anaesthetised rats. The urinary bladder response to L-DOPA was unchanged after blockade of cholinergic receptors with methylscopolamine, diminished after atropine and totally inhibited after hexamethonium. In addition, activation of muscarinic receptors in the pontine-mesencephalic brain region with oxotremorine after methylscopolamine pretreatment generates a hyperactive urinary bladder response, mediation of which seems to be independent of endogenous catecholamine stores. It is suggested that cholinergic receptors in the pontine-mesencephalic brain region are of importance for regulation of urinary bladder function in the rat. Furthermore, the bladder hyperactivity induced by L-DOPA might be propagated via muscarinic receptors in this brain area, and mediated peripherally via cholinergic receptors in the autonomic ganglia, but in the bladder detrusor via non-cholinergic receptors.