Neural control of substance P induced up-regulation and release of macrophage migration inhibitory factor in the rat bladder.
OBJECTIVE
Macrophage migration inhibitory factor is increased in intraluminal fluid after experimental inflammation and it mediates proinflammatory effects on the bladder. We examined the contribution of nerve activity and specific neurotransmitter systems to the mechanism of macrophage migration inhibitory factor release from the bladder during inflammation.


METHODS
Male Sprague-Dawley rats were anesthetized. The bladders were emptied and filled with saline. Rats received saline as a control (0.1 ml/100 gm body weight) or substance P (Sigma) (40 microg/kg in saline, 0.1 ml/100 gm body weight) subcutaneously as well as hexamethonium (Sigma) (50 mg/kg) intraperitoneally in saline (0.1 ml/100 gm body weight), lidocaine (2%, 0.3 ml) intravesically, atropine (Sigma) (3 mg/kg in saline, 0.1 ml/100 gm body weight) intravenously, propranolol (Sigma) (3 mg/kg in saline, 0.1 ml/100 gm body weight) intravenously or phentolamine (Sigma) (10 mg/kg in saline, 0.1 ml/100 gm body weight) intravenously. After 1 hour the intravesical fluid was removed and the bladder was excised. Macrophage migration inhibitory factor levels in intraluminal fluid were measured by enzyme-linked immunosorbent assay and Western blotting. MIF expression in bladder homogenates was examined using reverse transcriptase-polymerase chain reaction.


RESULTS
Intravesical lidocaine or ganglionic blockage with hexamethonium prevented substance P induced macrophage migration inhibitory factor release. In addition, pretreatment with atropine and phentolamine but not propranolol also prevented macrophage migration inhibitory factor release. While MIF up-regulation in the bladder was increased with substance P treatment, it was only prevented by intravesical lidocaine.


CONCLUSIONS
Substance P induced macrophage migration inhibitory factor release in the bladder is mediated through nerve activation. Postganglionic parasympathetic (via muscarinic receptors) and sympathetic (via alpha-adrenergic receptors) fibers mediate macrophage migration inhibitory factor release, while activating bladder afferent nerve terminals up-regulates MIF.
Vera
Pedro L
PL
Bay Pines Veterans Affairs Healthcare System, Research and Development, Bay Pines, Florida 33744, USA. pvera@health.usf.edu
Wang
Xihai
X
Meyer-Siegler
Katherine L
KL
D000818:Animals; D019746:Intramolecular Oxidoreductases / Q000378:metabolism*; D008263:Macrophage Migration-Inhibitory Factors / Q000378:metabolism*; D009476:Neurons, Efferent / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013373:Substance P / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology*; D001743:Urinary Bladder / Q000294:innervation* / Q000502:physiology*
D008263:Macrophage Migration-Inhibitory Factors; D013373:Substance P; D019746:Intramolecular Oxidoreductases; C515599:Mif protein, rat