Functional involvement of protein kinase C, Rho-kinase and TRPC3 decreases while PLC increases with advancement of pregnancy in mediating oxytocin-induced myometrial contractions in water buffaloes (Bubalus bubalis)

• Published in: Theriogenology Vol. 92; pp. 176 - 189
• Main Authors: Sharma, Abhishek, Nakade, Udayraj P., Choudhury, Soumen, Garg, Satish Kumar
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2017
• Subjects: Animals; Buffalo myometrium; Buffaloes - physiology; Calcium Channel Blockers - pharmacology; Enzyme Inhibitors - administration & dosage; Enzyme Inhibitors - pharmacology; Female; Gene Expression Regulation, Enzymologic; Imidazoles - pharmacology; Indicators and Reagents - pharmacology; Myometrium - drug effects; Nifedipine - pharmacology; Oxytocin; Oxytocin - pharmacology; Phospholipase-C; PKC; Pregnancy; Protein Kinase C - metabolism; Pyrazoles - pharmacology; rho-Associated Kinases - metabolism; Rho-kinase; Ruthenium Red - pharmacology; Store-operated Ca2+ channel/transient receptor potential channel; TRPC Cation Channels - genetics; TRPC Cation Channels - metabolism; Type C Phospholipases - genetics; Type C Phospholipases - metabolism; Uterine Contraction - drug effects; Uterine Contraction - physiology; Vasodilator Agents - administration & dosage; Vasodilator Agents - pharmacology; Phospholipase-C; Buffalo myometrium; Rho-kinase; PKC; Store-operated Ca2+ channel/transient receptor potential channel; Oxytocin; Store-operated Ca(2+) channel/transient receptor potential channel
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2016.12.008

Present study unravels the involvement of different calcium signaling pathways in oxytocin-induced contractions in myometrium of non-pregnant and pregnant buffaloes during early and mid-pregnancy stages. Uteri of pregnant animals were more sensitive than of non-pregnant buffaloes. Phasic contractions and frequency of contraction significantly increased with advancement of pregnancy, while tonic contractions non-significantly and amplitude significantly decreased from six months pregnancy onward. Oxytocin produced concentration-dependent-contraction on isolated myometrial strips of pregnant and non-pregnant buffaloes and the dose response curves (DRCs) of oxytocin were significantly (P < 0.05) shifted to right in the presence of nifedipine (1 μM), in Ca2+-free Ringer Locke solution (RLS), ruthenium red (30 μM), ruthenium red + nifedipine, cyclopiazonic acid (CPA; Ca2+ free RLS as well as RLS), CPA (10 μM)+nifedipine, U-73122 (1 μM) + nifedipine and SKF96365 (25 μM) on uteri of non-pregnant and pregnant (early and mid) animals. The DRCs were also significantly shifted towards right in the presence of Y-27632 (10 μM), GF109203X (5 μM) and Pyr3 (10 μM) on uteri of non-pregnant and early pregnancy stage buffaloes while only in the presence of U-73122 (1 μM) on uteri of mid-pregnancy stage buffaloes. Our finding suggest that and L-type Ca2+ channels, IP3-RyR-gated, and store-operated calcium channels including transient receptor potential channel (TRPC) pathways play significant role in mediating oxytocin-induced contractions in myometrium of pregnant and non-pregnant buffaloes. SERCA plays major role only during early-pregnancy while functional role of protein kinase C (PKC), Rho-kinase and TRPC3 pathways decreased and role of G-protein coupled receptor-phospholipase C (GPCR-PLC) pathway increased with advancement of pregnancy. •Uteri from pregnant buffaloes were more sensitive to oxytocin than of non-pregnant.•Oxytocin-induced uterotonic action is extracellular Ca2+/VDCC dependent.•Unlike pregnant, Ca2+ sensitization and PKC pathway play significant role in non-pregnant stage.•Functional role of PLC increases while TRPC3 decreases with advancement of pregnancy to mediate oxytocin-induced contraction.