RESUMO
The purpose of this paper is to explore the firing rate of the caudal photoreceptors (CPRs) from the sixth abdominal ganglion of the crayfish Cherax quadricarinatus. We use simultaneous extracellular recordings on left and right CPR in the isolated ganglion (n = 10). The CPRs showed an asymmetry in the spontaneous activity and light-induced response. In darkness, we observed one subgroup (70%) in which the left CPR (CPR-L) and right CPR (CPR-R) had spontaneous firing rates with a median of 18 impulses/s and 6 impulses/s, respectively. In another subgroup (20%), the CPR-R had a median of 15 impulses/s and the CPR-L had 8 impulses/s. In both groups, the differences were significant. Furthermore, the CPRs showed an asymmetrical photoresponse induced by a pulse of white light (700 Lux, 4 s). In one subgroup (30%), the CPR-L showed light-induced activity with a median of 73%, (interquartile range, IQR = 51), while the CPR-R had a median of 41%, (IQR = 47). In another subgroup (70%), the CPR-R showed a median of 56%, (IQR = 51) and the CPR-L had a median of 42%, (IQR = 46). In both groups, the differences were significant. Moreover, we observed a differential effect of temperature on CPR activity. These results suggest a functional asymmetry in both activities from left and right CPRs. These CPR activity fluctuations may modulate the processing of information by the nervous system.
Assuntos
Potenciais de Ação/fisiologia , Astacoidea/fisiologia , Lateralidade Funcional/fisiologia , Gânglios dos Invertebrados/fisiologia , Transdução de Sinal Luminoso/fisiologia , Células Fotorreceptoras de Invertebrados/fisiologia , Potenciais de Ação/efeitos da radiação , Animais , Astacoidea/efeitos da radiação , Relação Dose-Resposta à Radiação , Lateralidade Funcional/efeitos da radiação , Gânglios dos Invertebrados/efeitos da radiação , Luz , Transdução de Sinal Luminoso/efeitos da radiação , Estimulação Luminosa/métodos , Células Fotorreceptoras de Invertebrados/efeitos da radiação , Doses de RadiaçãoRESUMO
One of the most important functions modulated by melatonin is the synchronization of circadian rhythms. In crayfish (Procambarus clarkii), we have obtained evidence that the amplitude of the electrical response to light of the retinal photoreceptors the receptor potential, is modified by the action of melatonin and that the magnitude of this action depends on the circadian time of melatonin application. In contrast, the electroretinogram (ERG) circadian rhythm can be synchronized by either single or periodic melatonin application. In this work we hypothesized that, in crayfish, melatonin acts on effectors and on pacemaker of ERG circadian rhythm as a non-photic synchronizer. Melatonin could be a hormone that sends a signal of darkness to the ERG circadian system.