Depletion of central catecholamines alters amphetamine- and fenfluramine-induced taste aversions in the rat.

Abstract

Conditioned taste aversions induced by pairing the consumption of saccharin with an amphetamine injection are attenuated in rats with depletion of central catecholamines caused by intraventricular administration of 6-hydroxydopamine (6-OHDA). The hypothesis that dopamine (DA) depletion is responsible for this effect was tested. The reduction in conditioning caused by intraventricular 6-OHDA could not be duplicated either with injections of 6-OHDA into the substantia nigra (Experiment 1) or with intraventricular 6-OHDA injections in animals pretreated with desmethylimipramine (Experiment 2). Both treatments, however, produced large depletions of telencephalic DA. 6-Hydroxydopa infusions caused a preferential loss of telencephalic norepinephrine (NE) but also failed to alter taste aversion learning. It is concluded that the effect of intraventricular 6-OHDA on amphetamine-induced aversions was the result of depletion of both NE and DA. In a third experiment the generality of the effect was examined by pairing saccharin consumption with injections of the amphetamine congener fenfluramine. Depletion of both NE and DA failed to alter fenfluramine-induced aversions. Infusion of 6-OHDA into the substantia nigra, however, retarded the extinction of such an aversion. Evidence is discussed for a peripheral site of action for fenfluramine in the conditioned aversion paradigm.Many early laboratory studies of condi-mans, and all were found to be effective in tioned taste aversion (CTA) learning paired the CTA paradigm. Thus, it appeared that a taste stimulus with a treatment that in-any treatment capable of producing nausea duced gastric distress. This single pairing or gastrointestinal distress could be used to was sufficient to cause a suppression of the produce an aversion (Garcia & Koelling, consumption of that taste stimulus on later 1966). Recent data challenge this position, presentations. X-rays and a variety of Several highly toxic rodenticides do not indrugs, including cyclophosphamide, apo-duce CTA learning, although they produce morphine, and lithium chloride were among obvious signs of illness (Nachman & Hartley, the toxicosis-inducing agents tested (Garcia 1975). Furthermore, treatments that pro-

Influence of norepinephrine on somatosensory neuronal responses in the rat thalamus: A combined modeling and in vivo multi-channel, multi-neuron recording study

“…Second, increases in cell responsiveness coupled with decreases in response latency as observed with simulated NE input in the model have been postulated to enhance the tuning of a local circuit to sensory stimulation in vivo (Berridge & Waterhouse, 2003;Lorden et al, 1980;Selden et al, 1990). Our simulations show that modulating both EPSP and IPSP amplitude at the same time is more likely to decrease the latency and increase the responsiveness of thalamic cells than modulating either alone or modulating the leak current.…”

Anatomical disassociation of amphetamine's rewarding and aversive effects: An intracranial microinjection study

“…The vagal input synapses on noradrenergic neurons in the NST (Sumal et al 1983) and the NST also receives a dense noradrenergic input from the lateral tegmental system (Levitt and Moore 1979). While dopaminergic neurons have been shown to be critical for the amphetamine CTA (Wagner et al 1981), Lorden et al (1980) have also demonstrated a noradrenergic contribution using selective neurotoxin lesions. It is therefore possible that amphetamine's stimulation of these brainstem noradrenergic neurons contributes to the amphetamine-induced CTA.…”

Influence of fluid deprivation level on the extinction of conditioned taste aversion induced by amphetamine in female rats

“…A variety of substances, including apomorphine, cyclophosphamide, lithium chloride, amphetamine, scopolamine, morphine, and A9-THC, are known to produce taste aversion learning (Berger, 1972;Cappell, LeBlanc, & Endrenyi, 1973;Lorden, Callahan, & Dawson, 1980;Sklar & Amit, 1977). Unconditioned stimuli such as lithium chloride are thought to induce aversion via conditioning of their emetic properties.…”