Paper Title
Effect Of Pregnancy On Cholinergic Neurotransmitters In Rat Urinary Bladder

Abstract
OBJECTIVES: The urinary bladder suffers plastic changes during pregnancy. Since cholinergic innervation is responsible for micturation, and because bladder hyperactivity and urinary incontinence commonly occurred during pregnancy, therefore the current study investigates the effects of pregnancy oncholinergic responses on urinary bladder. Methods. 24 rats were used in this study. They were divided into two groups, control (non-pregnant) and pregnant (18–20 days). Isolated rat urinary detrusor muscle strips were suspended in organ baths containing Krebs’ solution for isometric tension recording. Tissue responses from the two groups toelectrical-field stimulation and cholinergic drugs were examined. Results. Electrical-field stimulations induced a rapid increase in basal tone, proportional to the frequency, representing endogenous cholinergic and purinergic effects. This response was higher in pregnant rat strips than control, while atropine effect was less than control. Exogenous ATP gave a higher dose-response curve in pregnant than control group, while exogenous acetylcholine and carbachol concentration-response curves were less for pregnant than control. Neostigmine, a cholinesterase inhibitor, effect was more pronounced in control than pregnant group confirming that this enzyme is less active during pregnancy. CONCLUSIONS: Pregnancy decrease exogenous cholinergic responses due to decrease the muscarinic receptors, while it increase endogenous cholinergic responses due to decrease cholinesterase enzyme activity or amount. These results may play a significant role in bladder hyperactivity and urinary incontinence during pregnancy.