Search

A structure-activity relationship study was undertaken for a variety of structural analogues of the tetracyclic antidepressant mianserin. Presynaptic alpha-blocking activity in vitro was evaluated measuring the potentiation of depolarization-induced noradrenaline (NA) release from rat cerebral cortex slices. Inhibition of NA and 5-hydroxytryptamine reuptake was measured in rat hypothalamic or striatal synaptosomes, respectively. Presynaptic alpha-blockade was only found in molecules with an overall bent shape. Flat rigid molecules or flexible ones were not active. Six-membered, chair-formed D-rings (containing the -NCH3 moiety) appeared better than 5- or 7-membered ones. Heteroatom substitution, but not hydroxylation or methylation, of the bridge between the two aromatic rings left presynaptic alpha-blockade unaffected. N-Demethylation and aromatic methyl- or chlorine-substitution reduced presynaptic alpha-blockade. In pyridine ring-substituted analogues the localization of the heteroatom appeared to be crucial. 5-Hydroxytryptamine reuptake inhibitory activity was only found in desmethylmianserin. NA uptake inhibition was found in many mianserin analogues, especially those with an exocyclic-N(CH3)2 moiety. Structure activity relationships for NA reuptake inhibition differed from those for presynaptic alpha-blockade and were generally less stringent. For both properties simple additivity relationships appeared to be absent.

A series of 33 1H-benz[de]isoquinolinecarboximidamides has been prepared and tested in the rat after intraperitoneal (ip) and/or oral (po) administration for their ability to inhibit the in vivo blood platelet aggregation induced by collagen. In this aggregation test, a considerable number of active compounds were found. Fourteen compounds were active when administered in [0.2 (mmol/kg)/day], five of which also exhibited significant po activity. One compound was toxic after ip administration but was found to be active after po administration without apparent toxicity. It is thought that the solubility of the drug in water is an important factor for the resorption after oral administration and, hence, for its oral activity.

The cholinergic neurotoxin, AF64A-picrylsulfonate, was unilaterally infused into the dorsal hippocampus of Wistar rats (2 nmol/2 microliters/4 min; A 6.2, Ls 1.5, H 6.5, Paxinos and Watson). After 19 days the for immunohistochemical staining of choline acetyltransferase (ChAT). Morphometry and counting of ChAT-immunoreactive profiles revealed shrinkage and disappearance of cholinergic neurons in the medial septum and diagonal band of Broca at the lesioned brain side. These data indicate a retrograde degeneration of cholinergic neurons following injection of AF64A-picrylsulfonate into the dorsal hippocampus of the rat.