PubMed · 3364654
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D R Turner. 1988. Intrapleural injection.. https://doi.org/10.1111/j.1365-2044.1988.tb05572.x
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In vertebrates local anaesthetics lead to various learning deficits, depending on the site and time of injection. In this study we show the effects of the local anaesthetic procaine on learning and memory in an invertebrate, the honeybee. Reversible blocking of neuronal processes leads to different memory deficits depending on the time window during which the local anaesthesia is in effect.
Spinally transected rats given leg shock whenever one hindlimb is extended learn to maintain the leg in a flexed position, which minimizes net shock exposure. Yoked rats, that receive an equal amount of shock independent of leg position (noncontingent shock), do not exhibit an increase in flexion duration. Yoked rats also fail to learn when response contingent shock is applied to the previously shocked leg, a behavioral deficit that resembles learned helplessness. This deficit could reflect either a peripheral (e.g. muscle fatigue) or central effect. Experiment 1 showed that spinalized rats given noncontingent shock to one hind limb fail to learn when response-contingent shock is applied to the contralateral leg. Experiment 2 demonstrated that blocking the afferent input to the spinal cord, by cutting the sciatic nerve, blocked the development of the deficit. Experiment 3 found that intrathecal lidocaine has a protective effect and prevents the deficit. These findings suggest that noncontingent nociceptive stimulation induces an intraspinal modification that undermines behavioral potential.
The present study was designed to examine whether noradrenergic projections from the A1 cell group in the ventrolateral medulla to the median preoptic nucleus (MnPO) transmit information from the peripheral baroreceptors. In urethane-anesthetized male rats, extracellular concentrations of noradrenaline (NA) in the region of the MnPO in response to hemorrhage (5 or 10 ml/kg) were monitored with in vivo microdialysis methods. Hemorrhage significantly increased the NA release in the MnPO area. The enhancement of NA release in the MnPO area caused by hemorrhage was significantly attenuated by previous injections of the local anesthetic lidocaine (2 %, 0.2 microl), but not by saline (0.2 microl), into the A1 region. These results suggest that the noradrenergic projections from the A1 region are important for carrying the peripheral baroreceptor information to the MnPO.