Activation of the inositol trisphosphate second messenger system by cAMP in a mouse fibroblast cell line

Sialylated milk oligosaccharides alter neurotransmitters and brain metabolites in piglets: an In vivo magnetic resonance spectroscopic (MRS) study

Background: Human milk contains high concentrations and diversity of sialylated oligosaccharides that have multifunctional health benefits, however, their potential role in optimizing neurodevelopment remains unknown.Objective: To investigate the effect of sialylated milk oligosaccharides (SMOS) intervention on neurotransmitters and brain metabolites in piglets.Methods: 3-day-old piglets were randomly allocated to one of three groups and fed either standard sow milk replacer (SMR) alone (n = 15), SMR supplemented with sialyllactose 9.5 g/kg (SL, n = 16) or a combination of SL and 6'-sialyllactosamine 9.5 g/kg (SL/SLN, n = 15) for 35 days. Brain spectra were acquired using a 3T Magnetic Resonance Spectroscopic (MRS) system.Results: SMOS fed piglets were observed to have significantly increased the absolute levels of myo-inositol (mIns) and glutamate + glutamine (Glx), in particular, the SL/SLN group. Similar findings were found in the relative amount of these metabolites calculated as ratios to creatine (Cr), choline (Cho) and N-acetylaspartate (NAA) respectively (P < .05). In addition, there were significant positive correlations of brain NAA, total NAA (TNAA), mIns, total Cho (TCho), total Cr (TCr), scyllo-Inositol (SI) and glutathione (Glth) with total white matter volume; Glu and SI with whole brain volume; and SI with whole brain weight respectively (P < .01). SLN and 3'SL intake were closely correlated with the levels of brain Glu, mlns and Glx in the treatment groups only (P < .01-.05).Conclusions: We provide in vivo evidences that milk SMOS can alter many important brain metabolites and neurotransmitters required for optimizing neurodevelopment in piglets, an animal model of human infants.

Hormone stimulation of type III adenylyl cyclase induces Ca2+ oscillations in HEK-293 cells

Various forms of cross-talk between the Ca2+ and cAMP signal transduction systems can occur in animal cells depending upon the types of adenylyl cyclases present. Here, we report that Ca2+ oscillations can be generated by hormone stimulation of type III adenylyl cyclase expressed in HEK-293 cells. These Ca2+ oscillations are apparently due to the unique regulatory features of type III adenylyl cyclase, which is stimulated by hormones and inhibited by elevated Ca2+ in vivo. Ca2+ oscillations were generated by glucagon, isoproterenol, or forskolin stimulation of type III adenylyl cyclase and were dependent upon the activity of cAMP- and calmodulin-dependent protein kinases. Ca2+ oscillations were not solely dependent upon cAMP increases since dibutyryl cAMP or (Sp)-cAMP did not stimulate Ca2+ oscillations. We hypothesize that stimulation of type III adenylyl cyclase leads to increased cAMP, activation of inositol 1,4,5-trisphosphate receptors, and elevation of intracellular Ca2+. As free Ca2+ increases, type III adenylyl cyclase activity is attenuated by CaM kinase(s) and intracellular cAMP levels decrease. When cAMP levels drop below a threshold level, the inositol 1,4,5-trisphosphate receptor is dephosphorylated and Ca2+ is resequestered. This cycle is repeated if type III adenylyl cyclase is chronically exposed to an activator. This unique mechanism for generation of Ca2+ oscillations in cells is distinct from others documented in the literature.