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The implication of GABA and glutamate signalling in the oxytocin-like modulation of social fear transmission in zebrafish
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Abstract(s)
Viver em grupos é uma característica conservada evolutivamente, que possibilita o uso de
informações sociais em diversas espécies, como o peixe-zebra. Quando um indivíduo é ferido,
é liberado uma substância de alarme espécie-específica. A resposta à substância inclui
movimentos erráticos e congelamento, que são estratégias para fugir de predadores. A
transmissão visual dessa resposta para outros possibilita benefícios de sobrevivência, e
também pode constituir uma forma ancestral de contágio emocional, baseada em mecanismos
de percepção-ação mais simples. Em mamíferos, o contágio da angústia implica a atividade
controlada pela ocitocina no Social Decision-Making Network (SDMN), particularmente, a
atividade excitatória e inibitória no septo lateral e estriado. Usando observações de respostas
de substâncias de alarme em outros, testamos a hipótese de que o contágio de estresse no
peixe-zebra depende da conservação desse mecanismo. Nós examinamos a atividade neuronal
(pS6), juntamente com marcadores inibitórios e excitatórios locais (GABA e Glutamato), em
regiões homólogas de peixe-zebra SDMN, o ventral (Vv) e o núcleo central da área
telencefálica ventral (Vc), durante o contágio visual de alarme - angústia induzida.
Descobrimos que o contágio de angústia, na forma de congelamento, leva a uma forte
diminuição da ativação inibitória em Vv, que retransmite informações de regiões de
comportamento social para a rede de recompensa mesolímbica. Além disso, encontramos
aumento na atividade glutamatérgica excitatória no Vc, que reside na rede de recompensa, e
impulsiona a resposta motora. Juntos, nossos primeiros resultados sugerem a presença de um
mecanismo para estímulos salientes, como angústia, para eliciar respostas de contágio.
ABSTRACT: Living in groups is an evolutionarily conserved characteristic that enables the use of social information in several species, such as zebrafish. When an individual of this species is injured it releases an alarm substance detected by conspecifics. The response to the substance includes erratic movements and freezing, which is a strategy for evading predators. The visual transmission of this response to others enables survival benefits, but it could also constitute an ancestral form of emotional contagion based on simpler perception-action mechanisms. In mammals, distress contagion implicates oxytocin-controlled activity in regions of the Social Decision-Making Network (SDMN), particularly excitatory and inhibitory activity in the lateral septum and the striatum. Using observations of alarm-substance responses in others, we tested the hypothesis that distress contagion in zebrafish relies on the conservation of this mechanism. We examined neuronal activity (pS6), together with local inhibitory and excitatory (GABA and Glutamate) markers, in homologous zebrafish SDMN regions, the ventral (Vv) and the central nucleus of the ventral telencephalic area (Vc), during visual contagion of alarm-induced distress. We found that distress contagion, in the form of freezing, drives a strong decrease of inhibitory activation in Vv, the lateral septum homologue that relays information from social behaviour regions to the mesolimbic reward network. Also, we found an increase in excitatory Glutaminergic activity in the Vc, the striatum homologue that resides in the reward network and drives motor response. Together, our early findings suggest the presence of a mechanism for salient stimuli, like distress, to elicit contagion responses.
ABSTRACT: Living in groups is an evolutionarily conserved characteristic that enables the use of social information in several species, such as zebrafish. When an individual of this species is injured it releases an alarm substance detected by conspecifics. The response to the substance includes erratic movements and freezing, which is a strategy for evading predators. The visual transmission of this response to others enables survival benefits, but it could also constitute an ancestral form of emotional contagion based on simpler perception-action mechanisms. In mammals, distress contagion implicates oxytocin-controlled activity in regions of the Social Decision-Making Network (SDMN), particularly excitatory and inhibitory activity in the lateral septum and the striatum. Using observations of alarm-substance responses in others, we tested the hypothesis that distress contagion in zebrafish relies on the conservation of this mechanism. We examined neuronal activity (pS6), together with local inhibitory and excitatory (GABA and Glutamate) markers, in homologous zebrafish SDMN regions, the ventral (Vv) and the central nucleus of the ventral telencephalic area (Vc), during visual contagion of alarm-induced distress. We found that distress contagion, in the form of freezing, drives a strong decrease of inhibitory activation in Vv, the lateral septum homologue that relays information from social behaviour regions to the mesolimbic reward network. Also, we found an increase in excitatory Glutaminergic activity in the Vc, the striatum homologue that resides in the reward network and drives motor response. Together, our early findings suggest the presence of a mechanism for salient stimuli, like distress, to elicit contagion responses.
Description
Dissertação submetida para a obtenção do grau de
Mestre em Neurociências comportamentais.
Keywords
GABA Zebrafish Glutamate signalling Oxytocin-like modulation Social behavior Distress contagion