Localization of 5′-ectonucleotidase/phosphatase activity within the olfactory sensilla of the spiny lobster,Panulirus argus

Summary Previous electrophysiological studies have shown that the olfactory organ (antennule) of the spiny lobster, Panulirus argus, has external chemoreceptors, which are selectively stimulated by adenosine 5-monophosphate (AMP) when present in seawater. Subsequent biochemical investigations revealed that AMP can be rapidly dephosphorylated by 5-ectonucleotidase/phosphatase activity associated with the olfactory sensilla (aesthetascs). In this study the deposition of cerium phosphate was used to examine the ultrastructural distribution of 5-ectonucleotidase/phosphatase activity in aesthetascs. Utilizing AMP as substrate, we found dephosphorylating activity to be associated with the outer membranes of both dendrites and auxiliary cells. Moreover, this activity was specifically localized to a narrow band that approximately corresponds to the transitional zone where dendrites develop cilia and branch extensively to form the outer dendritic segments. A similar distribution of the cerium phosphate reaction product was found when -glycerol phosphate was substituted for AMP. The alkaline-phosphatase inhibitor, levamisole, had no apparent effect on the deposition of reaction product when either AMP or -glycerol phosphate was used as substrate. The ectoenzymatic activity in the transitional zone may be of importance in clearing exogenous chemoexcitatory nucleotides from this region.Abbreviations ADP adenosine 5-diphosphate - AMP adenosine 5-monophosphate - ATP adenosine 5-triphosphate - EM electron microscopy     

Effects of Oenothera biennis L. and Hypericum perforatum L. extracts on some central nervous system myelin proteins,brain histopathology and oxidative stress in mice with experimental autoimmune encephalomyelitis

We investigated the effects of Oenothera biennis L. and Hypericum perforatum L. extracts on brain tissue histopathology, myelin oligodendrocyte glycoprotein (MOG), myelin basic protein (MBP), total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI) in mice with experimental autoimmune encephalomyelitis (EAE). Forty-seven C57BL/6J mice were divided into the following groups: multiple sclerosis (MS), control (healthy mice), MS + H. perforatum treated (MS + HP), MS + O. biennis treated (MS + OB). All groups except the control group were immunized by EAE methods. Two weeks after the immunization, the mice in the MS + HP group were fed normal food containing 18 ? 21 g/kg H. perforatum extract, the mice in MS + OB group were fed normal food containing 18 ? 21 g/kg O. biennis extract, and the mice in control and MS groups were fed normal food for six weeks. Brain tissue samples were collected from all mice for histopathological and biochemical analysis. Clinical signs of the disease were scored using functional systems scores (FSS) daily. The H. perforatum and O. biennis extracts ameliorated the increased brain tissue MOG and MBP values for animals with MS. H. perforatum and O. biennis extract decreased the TOS and OSI values for brain tissue and increased TAS levels in brain tissue of animals with MS. In addition, H. perforatum and O. biennis extracts decreased the clinical signs at the end of the experiment compared to the beginning of extract administration. We found that myelin was lost in MS group vs. control group. H. perforatum and O. biennis extract treatments decreased the amount of myelin loss in the MS + HP and MS + OB groups. We also observed amyloid deposition on vascular walls, in the cytoplasm of the neurons and in the intercellular space in the MS group. O. biennis and H. perforatum treated groups exhibited neither abnormal amyloid deposition nor obvious cell infiltration. The beneficial effects of O. biennis and H. perforatum for attenuating myelin loss and amyloid deposition suggest their therapeutic utility for treatment of MS.     

Physiological and chemical analysis of neurotransmitter candidates at a fast excitatory synapse in the jellyfish Cyanea capillata (Cnidaria, Scyphozoa)

Motor nerve net (MNN) neurons in the jellyfish Cyanea capillata communicate with one another by way of fast, bidirectional excitatory chemical synapses. As is the case with almost all identified chemical synapses in cnidarians, the identity of the neurotransmitter at these synapses is unclear. MNN neurons are large enough for stable intracellular recordings. This, together with the fact that they can be exposed, providing unlimited access to them and to their synapses, prompted a study of the action of a variety of neurotransmitter candidates, including those typically associated with fast synapses in higher animals. Only the amino acids taurine and β-alanine produced physiological responses consistent with those of the normal EPSP in these cells. Moreover, chemical analysis revealed that both taurine and β-alanine are present in the neurons and released by depolarization. These various findings strongly suggest that either or both of these amino acids, or a closely related compound is the neurotransmitter at the fast chemical synapses between MNN neurons.     

Trigeminal chemosensitivity: Differences in relation to the time of the day

Day-night differences of trigeminal chemosensitivity were investigated in 18 healthy volunteers employing both pain-related cortical potentials and pain ratings in response to stimulation of the nasal mucosa with CO2. Day-night differences were found with N 1 P2 amplitudes, P2 latencies and pain ratings. It is concluded that the time of the day must not be ignored when human chemosensitivity is investigated at suprathreshold levels.