Calcium influx and release mechanism(s) in histamine-induced myometrial contraction in buffaloes

Calcium signaling cascades differentially regulate PGF2α-induced myometrial contractions in water buffaloes (Bubalus bubalis)

This study unravels the differential involvement of calcium signaling pathway(s) in PGF_2α-induced contractions in myometrium of nonpregnant (NP) and pregnant buffaloes. Compared to the myometrium of pregnant animals, myometrium of NP buffaloes was more sensitive to PGF_2α as manifested by changes in mean integral tension (MIT) and tonicity. In the presence of nifedipine, myometrial contraction to PGF_2α was significantly attenuated in both NP and pregnant uteri; however, mibefradil and NNC 55-0396 produced inhibitory effects only in uterus of pregnant animals, thus suggesting the role of extracellular Ca²⁺ influx through nifedipine-sensitive L-type Ca²⁺-channels both in NP and pregnant, but T-type Ca²⁺ channels seem to play a role only during pregnancy. Entry of extracellular Ca²⁺ is triggered by enhanced functional involvement of Pyr3-sensitive TRPC3 channels and Rho-kinase pathways as evidenced by a significant rightward shift of the concentration-response curve of PGF_2α in the presence of Pyr3 and Y-27632 in NP myometrium. But significant down-expressions of TRPC3 and Rho-A proteins during pregnancy apparently facilitate uterine quiescence. In the presence of Ca²⁺-free solution and cyclopiazonic acid (SERCA blocker), feeble contraction to PGF_2α was observed in both NP and pregnant myometrium which suggests minor role of intracellular source of Ca²⁺ in mediating PGF_2α-induced contractions in these tissues.

Interaction between stress hormones and phagocytic cells and its effect on the health status of dairy cows: A review

Dairy cows are exposed to various stressors during their production cycle that makes them more susceptible to various diseases. Phagocytes (neutrophils and macrophages) are important soldiers of the innate immune system. Neutrophils are the first responders to an inflammatory response and stress and kill pathogens by generating reactive oxygen species and by the release of various antimicrobial peptides, enzymes, neutrophil extracellular trap formation, etc. Macrophages, the other phagocytes, are also the cleanup crew for the innate immune system that removes debris, pathogens, and dead neutrophils later on after an inflammatory response. The neuroendocrine system along with phagocytes exhibits an immunomodulatory potential during stressful conditions. Neuroendocrine system directly affects the activity of phagocytes by communicating bidirectionally through shared receptors and messenger molecules such as hormones, neurotransmitters, or cytokines. Different immune cells may show variable responses to each hormone. Short time exposure to stress can be beneficial, but repeated or extended exposure to stress may be detrimental to the overall health and well-being of an animal. Although some stresses associated with farming practices in dairy cows are unavoidable, better understanding of the interactions occurring between various stress hormones and phagocytic cells can help to reduce stress, improve productivity and animal welfare. This review highlights the role played by various stress hormones in modulating phagocytic cell performance of dairy cattle under inflammatory conditions.

WITHDRAWN: Differential involvement of L- and T-type Ca2+ channels, store-operated calcium channel (TRPC) and Rho-kinase signaling pathway(s) in PGF2α-induced contractions in myometrium of non-pregnant and pregnant buffaloes (Bubalus bubalis)

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Extra and intracellular calcium signaling pathway(s) differentially regulate histamine-induced myometrial contractions during early and mid-pregnancy stages in buffaloes (Bubalus bubalis)

This study examines the differential role of calcium signaling pathway(s) in histamine-induced uterotonic action during early and mid-pregnancy stages in buffaloes. Compared to mid pregnancy, tonic contraction, amplitude and mean-integral tension were significantly increased by histamine to produce myometrial contraction during early pregnancy with small effects on phasic contraction and frequency. Although uterotonic action of histamine during both stages of pregnancy is sensitive to nifedipine (a L-type Ca²⁺ channels blocker) and NNC55-0396 (T-type Ca²⁺ channels blocker), the role of extracellular calcium seems to be more significant during mid-pregnancy as in this stage histamine produced only 9.38±0.96% contraction in Ca²⁺ free-RLS compared to 21.60±1.45% in uteri of early pregnancy stage. Intracellular calcium plays major role in histamine-induced myometrial contraction during early pregnancy as compared to mid pregnancy, as in the presence of cyclopiazonic acid (CPA) Ca²⁺-free RLS, histamine produced significantly higher contraction in myometrial strips of early-pregancy in comparison to mid-pregnancy (10.59±1.58% and 3.13±0.46%, respectively). In the presence of U-73122, the DRC of histamine was significantly shifted towards right with decrease in maximal effect (E_max) only in early pregnancy suggesting the predominant role of phospholipase-C (PL-C) in this stage of pregnancy.