ABSTRACT
To characterize the effect of severe hypoxia on neuronal activity, long-term intracellular recordings were made from neurones in the isolated central ring ganglia of Lymnaea stagnalis. When a neurone at rest in normoxia was subjected to severe hypoxia, action potential firing frequency decreased by 38% (from 2.4-1.5 spikes s(-1)), and the resting membrane potential hyperpolarized from -70.3 to -75.1 mV. Blocking GABA(A) receptor-mediated synaptic transmission with the antagonist bicuculline methiodide (100 micromol l(-1)) decreased neuronal activity by 36%, and prevented any further changes in response to severe hypoxia, indicating that GABAergic neurotransmission mediates the severe hypoxia-induced decrease in neuronal activity. Puffing 100 micromol l(-1) GABA onto the cell body produced an excitatory response characterized by a transient increase in action potential (AP) firing, which was significantly decreased in severe hypoxia. Perturbing intracellular chloride concentrations with the Na+/K+/Cl- (NKCC1) cotransporter antagonist bumetanide (100 micromol l(-1)) decreased AP firing by 40%, consistent with GABA being an excitatory neurotransmitter in the adult Lymnaea CNS. Taken together, these studies indicate that severe hypoxia reduces the activity of NKCC1, leading to a reduction in excitatory GABAergic transmission, which results in a hyperpolarization of the resting membrane potential (Vm) and as a result decreased AP frequency.
Subject(s)
Ganglia, Invertebrate/physiology , Lymnaea/physiology , Neurons/physiology , gamma-Aminobutyric Acid/physiology , Action Potentials , Animals , Ganglia, Invertebrate/cytology , In Vitro Techniques , OxygenABSTRACT
Experimental techniques that we have found useful during our studies of insect blood-feeding behaviour are reviewed. Some of the principal findings resulting from these techniques are discussed. Where directly applicable, the work of others is included, but no complete review of the subject has been attempted.
Subject(s)
Risk Assessment , Insect Vectors , Insecta , Environmental MisconductABSTRACT
This paper continues a discussion of approaches and methodologies we have used in our studies of feeding in haematophagous insects. Described are techniques for directly monitoring behaviour: electrical recording of feeding behaviour via resistance changes in the food canal, optical methods for monitoring mouthpart activity, and a computer technique for behavioural event recording. Also described is the use of "flow charts" or "decision diagrams" to model interrelated sequences of behaviours.
Subject(s)
Humans , Host-Seeking Behavior , Culicidae/physiology , Electronic Health RecordsABSTRACT
Se tratan diversas técnicas de cría y alimentación de triatominos en el laboratorio, analizándose las ventajas, desventajas y resultados, tanto de aquellas técnicas que requieren animales vivos, como de las que emplean alimentación artificial en base a dietas con sangre de un vertebrado tratada de diversas formas, y que, generalmente, tiene lugar a través de membranas artificiales, y las que utilizan dietas no nutritivas. Se mencionan técnicas de estudio del comportamiento alimentario de los triatominos y sus posibles aplicaciones para la investigación
Subject(s)
Animals , Nutritional Support/methods , Animal Feed , Chagas Disease/prevention & control , Feeding Behavior , Insect Vectors , TriatominaeABSTRACT
Se revisa literatura existente sobre alimentación, procesos post-alimenticios y vuelvo de triatominos (Rhdnius prolixus, Triatoma infestans y Panstrongylus megistus fueron las especies más estudiadas), considerándose aspectos de la conducta alimentaria, localización de huéspedes, digestión, nutrición, metabolismo, excreción, requerimientos nutricionales, comensalismo (simbiontes), efectos de la carencia de alimentos, papel de la alimentación en el desarrollo, ecdisis y reproducción; y aspectos del vuelo: iniciación, balancehídrico durante el mismo y metabolismo (mencionándose el papel de los aminoácidos como fuente energética)
