ABSTRACT
Experiments on the models of epileptiform seizure and hemorrhagic stroke (Krushinskii-Molodkina rats) showed that selective inhibitors of inducible and neuronal NO synthases (aminoguanidine and 7-nitroindazole) significantly decrease the mortality rate, reduce the severity of motor disorders, and prevent the development of intracranial hemorrhages under conditions of audiogenic stress.
Subject(s)
Enzyme Inhibitors/therapeutic use , Guanidines/therapeutic use , Indazoles/therapeutic use , Nitric Oxide Synthase Type III/antagonists & inhibitors , Nitric Oxide Synthase Type I/antagonists & inhibitors , Stress, Physiological/physiology , Animals , Male , Rats , Seizures/drug therapy , Seizures/prevention & control , Shock, Hemorrhagic/prevention & controlABSTRACT
Previous studies have shown that nitric oxide (NO) transforms the responses of various neurons to glutamate, though it remained unclear whether this mechanism is involved in the formation of behavior. We therefore studied the buccal generator of the feeding rhythm of the mollusk Lymnaea stagnalis (pond snail). In this organism, glutamate and NO are synthesized by defined neurons; glutamate is the neurotransmitter for the second phase of the standard triphasic feeding rhythm. Motoneuron B4 was used for monitoring. Studies using isolated CNS preparations showed that in some cases glutamate evoked hyperpolarization of B4 and terminated rhythmic network activity (n=17; group 1), while in other cases glutamate evoked depolarization of B4 and activation of a non-standard biphasic rhythm (n=12; group 2). In group 1, the NO donor nitroprusside lifted the inhibitory effect of glutamate (n=13), with transformation into an excitatory effect in nine cases. In group 2, the NO acceptor PTIO transformed the excitatory effect of glutamate into an inhibitory effect (n=7). These results provide evidence that: 1) the responses of the central generator of the buccal motor rhythm to glutamate depend on the NO level, and 2) this regulatory mechanism can modify feeding behavior.
Subject(s)
Ganglia, Invertebrate/metabolism , Glutamic Acid/metabolism , Motor Neurons/physiology , Nerve Net/metabolism , Nitric Oxide/metabolism , Animals , Feeding Behavior/physiology , In Vitro Techniques , Lymnaea , Pattern Recognition, Physiological/physiologyABSTRACT
The mechanisms of the effects of some types of behavior on others have received little study. The present investigation addresses the phenomenon present in male crickets of the species Gryllus bimaculatus, consisting of the powerful activation by transient flight (3 min) of aggression to another male and of the female courtship program. We found that flight did not evoke these behavioral changes in males injected with the NO synthase inhibitor LNNA. The intensity and duration of fights with another male, the frequency of ritual singing by the victor, and the intensity with which the victor pursued the vanquished only increased significantly after flight in control male crickets injected with Ringer's solution, but not in experimental crickets. Similarly, flown males injected with LNNA were no different from unflown males in terms of the intensity of female courtship (the latent period and relative duration of courtship singing); in controls, the latent period was significantly shorter and the duration of singing was significantly greater in flown crickets. LNNA had no effect on aggressive or sexual behavior in unflown males. These results demonstrate that flight may increase NO synthesis, making a significant contribution to the formation of the flight-evoked behavioral state.
Subject(s)
Aggression/physiology , Gryllidae/physiology , Nitric Oxide Synthase/physiology , Sexual Behavior, Animal/physiology , Aggression/drug effects , Analysis of Variance , Animals , Enzyme Inhibitors/pharmacology , Flight, Animal/physiology , Gryllidae/drug effects , Male , Nitric Oxide Synthase/antagonists & inhibitors , Nitroarginine/pharmacology , Sexual Behavior, Animal/drug effectsABSTRACT
The role of the serotoninergic and opioid systems in the choice between a passive defensive and an orienting response of the mollusc Lymnaea stagnalis to the presentation of an unfamiliar object was studied. Under the influence of 5-HTP, a metabolic precursor of serotonin, orienting and investigatory behavior was activated; the number of protective reactions decreased. Under the influence of naloxone, an antagonist of opiate receptors, the proportion of orienting responses decreased, and the number of passive defensive avoidance and freezing reactions increased. The influence of the agents investigated on the attitude of the snail to a novel object was found to be well coordinated with their influence on other forms of behavior and the behavioral state of the mollusc as a whole.
