High‐affinity uptake of [³H]serotonin in cultured neurones of the cockroach Periplaneta americana

Abstract

Cultured central neurones from the American cockroach, Periplaneta arnericana, have been used to investigate the uptake of [3H]serotonin. The neurones accumulate [3H]serotonin from the extracellular medium by both a highand a low-affinity system. The activity of the high-affinity mechanism i s decreased by low temperature and metabolic poisons, and i s dependent on sodium and chloride ions. Both depolarising levels of external potassium ions and veratridine decrease the high-affinity uptake system, suggesting it is influenced by the transmembrane potential. The pyrethroid insecticides, deltamethrin and permethrin, enhance the inhibitory effect of veratridine. Pyrethroid enhancement is completely blocked by tetrodotoxin, and neither pyrethroid affects the uptake system in the absence of veratridine. Avermectin BI A is a powerful inhibitor of the high-affinity uptake system, and its effect i s blocked by picrotoxin. High-affinity uptake of [3H]serotonin i s inhibited by imipramine and amitriptyline; desipramine has no significant effect on this uptake. The activity of the high-affinity system is also reduced by 8-hydroxy-dipropylaminotetralin, a-methyl-serotonin, and l-(3-chloropheny1)piperazine. Dopamine, noradrenaline, octopamine, and the formamidine insecticides, chlordimeform and demethylchlordimerform, are moderate inhibitors of the high-affinity uptake system. The formamidine effect is not blocked by tetrodotoxin or picrotoxin.

Hypoxia induces different responses of striatal high- and low-affinity dopamine uptake sites

“…1971). However, kinetic studies have indicated that high-and low-affinity DA uptake may be mediated by one carrier (Berndt et al, 1991) and the same may be assumed for other neurotransmitters such as noradrenaline (Banerjee et al, 1987), serotonin (Bermudez and Beadle, 1989), and the uptake of choline (Chatterjee et al, 1987). Moreover, both high-and lowaffinity catecholamine uptake have been measured in cultured astrocytes (Kimelberg, 1986) and there is evidence suggesting that dopaminergic neurons perform low-affinity uptake too (Stamford et al, 1986).…”

Efectos de reserpina y p-cloranfetamina en el metabolismo y la liberación de 5-HT en el ganglio cerebral de Inachis io (Lepidoptera).

“…The dynamics of the 5-HT system in insects shares several features with vertebrates, including (a) 5-HT synthesis from tryptophan (3,7), (b) calcium-dependent release and activation of second messengers (15,29), and (c) recapture by nerve endings (2) for subsequent inactivation. In insects, however, the main catabolic process for inactivation of 5-HT is N-acetylation (44), although inactivation of 5-HT by oxidative deamination may also take place, since 5-hydroxyindoleacetic acid (5-HIAA) has been detected in the nervous system of some insect species (49)(50)(51)(52).…”