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Biomedical subjects

Z W Brown

Publications and source records attributed to Z W Brown.

30 records · Page 2Linked to original sources
PubMed1979

Intraventricular self-administration of acetaldehyde, but not ethanol, in naive laboratory rats.

For 11 consecutive days, naive rats were maintained in operant chambers where they were given the opportunity to self-administer acetaldehyde (1,2, or 5% v/v), ethanol (2 or 10% v/v), or pH control solutions directly into the cerebral ventricles. Only the animals that had access to the 2 and 5% acetaldehyde solutions showed rates of lever pressing significantly higher than controls. It is suggested that acetaldehyde rather than ethanol itself may mediate the positive reinforcing effects of ethanol in the brain.

Acetaldehyde↗
PubMed1979

Disruption of taste aversion learning by pretreatment with diazepam and morphine.

Laboratory rats were pretreated with either morphine (9 mg/kg IP), diazepam (4 mg/kg 1P) or Ringer's solution 2, 3 1/2, and 2 hr, respectively, prior to ingestion of a novel tasting saccharin solution followed immediately by a single injection of one of these agents. Animals pretreated with Ringer's solution followed by an injection of either morphine or diazepam showed a conditioned taste aversion (CTA) as determined by a significant reduction in the mean saccharin intake on a subsequent test trial. Although the drug pretreatments alone produced no conditioned avoidance behavior, the diazepam pretreatment completely blocked the development of both diazepam and morphine-evoked CTAs while the morphine pretreatment prevented a CTA induced by itself but not by diazepam. The results were discussed in terms of the attenuating effects of the pretreatments on the relative saliency of the subsequent conditioning drug injection.

Animals↗
PubMed1979

Attenuation of ethanol intake by 5-hydroxytryptamine uptake blockade in laboratory rats. I. Involvement of brain 5-hydroxytryptamine in the mediation of the positive reinforcing properties of ethanol.

The role of 5-hydroxytryptamine (5-HT) uptake blockade in the mediation of the positive reinforcing peroperties of ethanol in male wistar rats was investigated. It was demonstrated that treatment with zimelidine (H102/09) a 5-HT uptake inhibitor, specifically attenuated ethanol consumption. In an attempt to extinguish the ethanol drinking response, ethanol preferring animals in a second experiment, were provided with ethanol as the only source of fluid in combination with zimelidine treatment. Animals treated in such a manner subsequently reduced their ethanol consumption when presented with a free-choice between ethanol and water. These results were attributed to an increased availability of central 5-HT, suggesting that central 5-HT mechanisms may in some way be involved in the mediation of the positive reinforcing properties of ethanol.

Alcohol Drinking↗
PubMed1978

Suppression of voluntary ingestion of morphine by inhibition of dopamine-beta-hydroxylase.

Male Wistar rats were exposed to a free choice between water and a morphine-sucrose solution. Following stabilization of baseline levels of consumption of morphine, the animals were injected for 5 consecutive days with either FLA-57 (45 or 60 mg/kg i.p.), a non-toxic dopamine-beta-hydroxylase inhibitor or its vehicle. The FLA-57 treated animals significantly attenuated their preference for morphine during the injection and post-injection periods although there were no significant differences related to the dosages used. These treatments produced a concomitant reduction in central norepinephrine levels suggesting that norepinephrine may be involved in the mediation of the reinforcing properties of morphine consumed by laboratory rats. The possibility of common neural mechanisms regulating the pharmacological actions of both morphine and ethanol are discussed.

Animals↗
PubMed1977

Differential motor effects of intraventricular infusion of morphine and etonitazene.

The motor effects produced by intraventricular infusions of morphine were compared to the effects of etonitazene. Despite the similarity in the peripheral actions of these drugs, motor effects of central infusions differed dramatically. Intraventricular morphine infusions resulted in explosive motor behavior whereas etonitazene produced extreme muscular rigidity. The periaqueductal grey (PAG) has been proposed as the substrate of morphine-induced explosive motor behavior. However, considerations of the dose of morphine and the mobility of this drug in tissue suggests that sites other than the PAG may also be involved in explosive motor behavior.

Analgesics, Opioid↗
PubMed1977

Noradrenergic mediation of the positive reinforcing properties of ethanol: I. Suppression of ethanol consumption in laboratory rats following dopamine-beta-hydroxylase inhibition.

Ethanol-drinking rats were injected with the dopamine-beta-hydroxylase inhibitor FLA-57, prior to free-choice presentations of ethanol and water either for 5 alternate days (25 or 40 mg/kg i.p.) or for 5 consecutive days (45 mg/kg i.p.). In all cases, the FLA-57 treated animals markedly attenuated ethanol consumption while vehicle-injected controls showed no change from baseline. In the post-injection period ethanol intake gradually returned to baseline levels. Biochemical assays revealed that whole brain norepinephrine levels following injection of FLA-57 (15-60 mg/kg i.p.) were significantly depressed while dopamine and serotonin levels were slightly increased. It is suggested that norepinephrine may be involved in the mediation of the positive reinforcing properties of ethanol regulating its self-administration.

Alcohol Drinking↗
PubMed1977

Noradrenergic mediation of the positive reinforcing properties of ethanol: II. Extinction of ethanol-drinking behavior in laboratory rats by inhibition of dopamine-beta-hydroxylase. Implications for treatment procedures in human alcoholics.

Following stabilization of consumption of a 15% (v/v) ethanol solution in a free-choice with water, rats were presented with a forced-choice of ethanol for 10 consecutive alternate days. Prior to each forced-choice presentation experimental animals were injected with the non-toxic dopamine-beta-hydroxylase inhibitor FLA-57 (30 mg/kg i.p.) while control animals received only vehicle injections. At the termination of the injection phase when ethanol was again made available in a free-choice with water, ethanol consumption for the FLA-57 treated animals was markedly suppressed. These data are interpreted in terms of extinction resulting from the procedure whereby performance of the ethanol drinking response was perpetuated by force with the pharmacological reinforcing properties being blocked by FLA-57-induced depletions of norepinephrine. Applications of these procedures in the treatment of human alcoholics are discussed.

Alcohol Drinking↗
PubMed1976

Intraventricular self-administration of morphine in naive laboratory rats.

Male Wistar rats implanted with cannulae aimed at the left lateral cerebral ventricle were individually maintained in Skinner boxes for 11 consecutive days. Animals were neither predependent on morphine nor shaped to press the operant lever. Experimental animals (n = 7) obtained intraventricular infusions of a 1% morphine HCl solution (2 mul per 5-s infusion) for each lever press while control animals (n = 7) received only the vehicle. Four animals were yoked to experimental animals and received equivalent but non-contingent morphine HCl infusions. The mean number of lever presses per day for the experimental group was significantly higher than for the vehicle control or yoked control groups suggesting that naive rats will work for the positive reinforcing properties of morphine when it is infused centrally.

Animals↗
PubMedDate not supplied

Possible involvement of acetaldehyde, norepinephrine and their tetrahydroisoquinoline derivatives in the regulation of ethanol seld-administration.

In this study, we examined the possible role of acetaldehyde in the mediation of the reinforcing properties of ethanol. We also examined the possible interaction of acetaldehyde and brain norepinephrine in this mediation. We found that rats will self-administer acetaldehyde delivered into the cerebral ventricles, and that this operant behaviour can be attenuated by injections of a dopamine-beta-hydroxylase inhibitor. The results are discussed in terms of a role for tetrahydroisoquinoline alkaloids in alcoholism.

Acetaldehyde↗