Octopamine agonists

Table 23 Physicochemical properties and octopamine agonist activity of 2-(arylimino)thi-azolodines (Fig. 34) [203]...

On the basis of this model, it has been concluded that more hydrophobic compounds having ortho and para substituents with an electron-withdrawing property and less bulky meta-position substituents would lead to better activity. In these compounds octopamine agonistic activity in terms of K, the concentration of the agonist necessary for half-maximal activation of adenylate cyclase, and its log Vmax are mutually correlated. This has prompted us to suggest that the larger the V"max value, the greater would be the activity of the compounds [202]. 

Ki is the concentration of octopamine agonist necessary for half-maximal inhibition of pheromone biosynthesis activating neuropeptide (PBAN) binding at 1 p mol/intersegment Eq. 51 [215]... 

Interest in octopamine receptors has grown with the discovery that a novel group of pesticides, the formamidines, are octopamine agonists (95). Thus chlordimeform (CDM) or demethylchlordimeform (DCDM) are able to activate octopamine receptors in firefly lantern (95,96), tobacco hornworm central nervous system (88), locust skeletal muscle (97), locust oviduct muscle (91,), locust corpora cardiaca (98), locust fat body (99). and cockroach haemocytes (39). 

Through use of the virtually pure octopaminergic firefly system, we have now acquired some idea of the structure-activity requirements for activation of this octopamine-sensitive adenylate cyclase. Furthermore, by quantitating the octopamine agonist potencies of a large series of chemically-related derivatives, we are now in an excellent position to characterize octopamine receptors in other, less homogenous tissues as well as in other insect species. 

---