neuropeptide-y and staurosporine-aglycone

Our recent study showed that prenatal and early postnatal exposure of mice to side-steam tobacco smoke (SS), a surrogate to environmental tobacco smoke (ETS), leads to increased airway responsiveness and sensory innervation later in life. However, the underlying mechanism initiated in early life that affects airway responses later in life remains undefined. The concomitant increase in nerve growth factor (NGF) after exposures suggests that NGF may be involved the regulation of airway innervation. Since NGF regulates sympathetic nerve responses, as well as sensory nerves, we extended previous studies by examining neuropeptide Y (NPY), a neuropeptide associated with sympathetic nerves. Different age groups of mice, postnatal day (PD) 2 and PD21, were exposed to either SS or filtered air (FA) for 10 consecutive days. The level of NPY protein in lung and the density of NPY nerve fibers in tracheal smooth muscle were significantly increased in the PD2-11SS exposure group compared with PD2-11FA exposure. At the same time, the level of NGF in lung tissue was significantly elevated in the PD2-11SS exposure groups. However, neither NPY (protein or nerves) nor NGF levels were significantly altered in PD21-30SS exposure group compared with the PD21-30FA exposure group. Furthermore, pretreatment with NGF antibody or K252a, which inhibits a key enzyme (tyrosine kinase) in the transduction pathway for NGF receptor binding, significantly diminished SS-enhanced NPY tracheal smooth muscle innervation and the increase in methacholine-induced airway resistance. These findings show that SS exposure in early life increases NPY tracheal innervation and alters pulmonary function and that these changes are mediated through the NGF.

Topics: Age Factors; Airway Resistance; Animals; Animals, Newborn; Asthma; Carbazoles; Indole Alkaloids; Methacholine Chloride; Mice; Mice, Inbred ICR; Muscle, Smooth; Nerve Fibers; Nerve Growth Factor; Neuropeptide Y; Protein-Tyrosine Kinases; Tobacco Smoke Pollution; Trachea

In adult mice, intrahippocampal administration of kainic acid induces a structural modification of the granule cell layer reminiscent of granule cell dispersion (GCD) seen in humans with temporal lobe epilepsy. We tested that GCD might be involved in the patterns of granule cell responses to perforant path stimulation by recording field potentials in vivo after kainic acid-induced status epilepticus until the phase of chronic seizure activity in presence of GCD or after its alteration by K252a co-treatment, an inhibitor of tyrosine kinase activities. Stimulation triggered bursts of multiple population spikes, the number of which progressively increased with time whereas their amplitude decreased in parallel with the progressive decrease in granule cell density. The population spike threshold was reached for a lower excitatory synaptic drive than in controls, as assessed by the initial slope of the field excitatory post-synaptic potential. This indicates that, for identical synaptic responses, granule cells were closer to the firing threshold. Fast inhibition, assessed by paired pulse stimulation, was compromised immediately after the initial status epilepticus, consistent with the rapid loss of most hilar cells. Neither the epileptic course nor the epileptiform responses of the granule cells were modified and manipulation by alteration following GCD manipulation while granule cell neuropeptide-Y immunostaining was substantially decreased. In this mouse model of TLE, granule cells display a progressive increase in epileptiform responses to afferent input until the occurrence of spontaneous seizures. The population spike amplitude decreases in parallel with GCD while the granule cell excitability is enhanced. Consequently, data from field potentials in epilepsy experiments should be interpreted with care, taking into account the possible variations in the neuronal density in the recorded area.

Topics: Action Potentials; Animals; Behavior, Animal; Carbazoles; Cell Count; Disease Models, Animal; Dose-Response Relationship, Radiation; Drug Interactions; Electric Stimulation; Enzyme Inhibitors; Epilepsy; Hippocampus; Immunohistochemistry; Indole Alkaloids; Kainic Acid; Mice; Neurons; Neuropeptide Y; Perforant Pathway; Staining and Labeling; Time Factors

In this study, we investigated the possible involvement of protein kinase C in the inhibitory effect of neuropeptide Y (NPY) on the electrical stimulation-induced release of radioactivity from mouse atria incubated with [3H]-noradrenaline. The protein kinase C activators, phorbol dibutyrate (PDB, 0.001-1 mumol/l) and phorbol myristate acetate (PMA, 0.001-1 mumol/l), increased the release of noradrenaline in a concentration-dependent manner. Interestingly, the maximum effect on noradrenaline release was significantly greater for phorbol dibutyrate compared to phorbol myristate acetate. The enhancement produced by both phorbol esters was significantly reduced by the protein kinase C inhibitor, K-252a (1 mumol/l). In the presence of the concentration of either phorbol ester (PMA, 0.1 mumol/l, PDB 1 mumol/l), that was supramaximal for increasing the release of noradrenaline, NPY (0.3 mumol/l) significantly inhibited the release of noradrenaline. Moreover, in the presence of the protein kinase C inhibitors, K-252a (1 mumol/l) or polymyxin B (70 mumol/l), NPY (0.3 mumol/l) also significantly inhibited the release of noradrenaline. Therefore, it is concluded that protein kinase C is not involved in the prejunctional inhibitory effect of NPY on noradrenaline release in the mouse atria. Furthermore, since K-252a also inhibits cyclic AMP-dependent protein kinase, cyclic GMP-dependent protein kinase and myosin light chain kinase, it is likely that these kinases are also not involved in the inhibitory mechanism of NPY.

Topics: Animals; Carbazoles; Electric Stimulation; Enzyme Activation; Female; Heart; Heart Atria; In Vitro Techniques; Indole Alkaloids; Mice; Neuropeptide Y; Norepinephrine; Phorbol 12,13-Dibutyrate; Polymyxin B; Protein Kinase C; Tetradecanoylphorbol Acetate; Tritium