Synaptic differences, application

Kainate (200 nM) renders the mossy-fiber axons more excitable, as evidenced by an increase in the presynaptic fiber volley as well as lowered threshold for antidromic action potentials. At the same time, a kainate-induced suppression of synaptic transmission and depression of presynaptic calcium influx was observed (92). In contrast, application of very low concentrations of kainate (50 nM) facilitates synaptic transmission at the mossy fibers (77,100). The kainate-induced facilitation is blocked by LY382884, suggesting a role for GLUK5-containing receptors (77). However, only depression of transmission has been observed with ATPA (35). Thus, the facilitatory and depressory effects of kainate could be mediated by different receptor populations that have distinct pharmacological properties. 

Francis placed strips of the retina from different animals in sodium sulphate to precipitate the cholinesterase in situ. Some strips were then incubated with acetylthiocholine, while others were kept in D.F.P. solution before the incubation. The tissues after preliminary washings were then treated with appropriate reagents so as to precipitate the copper derivative of thio-choline. The sections ultimately obtained showed dark deposits at those points where the enzyme was present, and deposits were absent if D.F.P. had destroyed the enzyme. As a result of the application of this technique, Francis was able to establish that for all the animals examined, except the frog, true cholinesterase was present only at the inner synaptic layer. 

Desynchronization of PNs affects the specificity of neurons in the P-lobes of the mushroom bodies (a neural convergence site post-synaptic to the calyces) (MacLeod el al., 1998). Application of picrotoxin to the AL resulted in a decreased ability of P-lobe neurons to correctly identify odors. Single P-lobe neurons showed responses to odors after desynchronization to which they were formerly silent and responses to similar odors lost odor-specific temporal features seen prior to picrotoxin application. These differences were never seen in PNs and the authors concluded that information is sampled across assemblies of responding PNs and that this information converges onto single neurons in the p-lobe. Thus, neurons downstream of the AL appear to read and decode temporal information conveyed by neurons leaving the AL. 

Notably, pseudoephedrine is a diastereomer of ephedrine and considerably racemic ephedrine (dl-ephedrine) has not been found naturally, however, it is prepared synthetically and is inactive for commercial purposes. Ephedrine and pseudoephedrine are completely stable compounds under changing temperature conditions, but they are quite unstable when exposed to sunlight or in the presence of oxygen pressure [2]. The unique molecular structure of ephedrine causes its different stereoisomers to be valuable for pharmaceutical applications such as nasal decongestant, pupil dilator, bronchodilator, and central nervous system stimulant. Ephedrine is a sympathomimetic substance and the principle mechanism of ephedrine activity is its influence, by enhancing the activity of noradren-alin, on post-synaptic a- and (3-receptors in the nervous system. Stimulation of a 1-adrenergic receptors produces contraction of vascular smooth muscle. 

---