Withdrawal In Rats Research Articles

Repeated characterization of alcohol withdrawal reactions in rats chronically exposed to an alcohol liquid diet

1. 1. Rats given a 10-% (v/v) alcohol liquid diet over long periods of time reach high blood alcohol levels of more than 200 mg/dl over several weeks. 2. 2. Repeated discontinuation of the alcohol intake resulted, each time within 8 hr, in several withdrawal reactions including a reduction in exploratory behaviour and tremorogenic activity. 3. 3. The inhibition of exploratory activity was measured in a neutral two-chamber model, both in terms of the number of transits into the open area as well as the time spent in the open space. The differences in exploration remained over the 4 successive withdrawal tests. 4. 4. Rats in alcohol withdrawal were also consistently less active than control animals in the tremor cages equipped with a piezofilm floor, and this despite the presence of a clearly visible tremor in the hindpaws when lifted up. 5. 5. Alcohol withdrawal rats revealed a more frequent tremor activity than controls after a challenge with 5 mg/kg harmine. This effect was independent of the length of the tremor bursts used to quantify harmine-induced tremor starting from the second withdrawal period onwards. 6. 6. With a dose of 10 mg/kg harmine, ceiling effects were reached in both the alcohol withdrawal and control rats and differences between the two groups were only present during the first exposures. 7. 7. Overall, these results indicate that it is possible to quantify some withdrawal reactions at repeated time intervals of alcohol cessation in rats chronically exposed to a 10-% alcohol liquid diet. As a consequence, these withdrawal reactions can be studied in a more systematic way.

P-121 - Changes of glutamate receptors and c-fos expression in the brain of phenobarbital-dependent and withdrawn rats.

P-121 - Changes of glutamate receptors and c-fos expression in the brain of phenobarbital-dependent and withdrawn rats.

Structural changes in the hippocampal formation after long-term alcohol consumption and withdrawal in the rat.

The effects of long-term alcohol consumption and withdrawal upon the structure of the rat hippocampal formation were studied by applying morphometric methods to material processed for light and electron microscopy. The somatostatinergic neurons of the hilus were also studied. Groups of 6 rats were treated as follows: (a) given alcohol for 6, 12 and 18 months; (b) paired controls; and (c) rats switched to a normal diet in the 6 months after 6 and 12 months of alcohol intake. A progressive loss of hippocampal neurons after chronic alcohol consumption was found. The loss was aggravated during withdrawal from alcohol, with the exception of the hilar cells. The dendrites of granule cells from the alcohol-treated rats displayed signs of regrowing, but they did not do so in rats withdrawn from alcohol. The synapses between mossy fibre terminals and CA3 dendrites appear to be rather resistant to alcohol insult, and evidence of morphological plasticity was found in withdrawn rats. If an homology can be established between humans and rodents then the changes observed in alcohol-fed rats can be regarded as underpinning some of the functional and behavioural alterations depicted under these circumstances. The peculiar changes found in some nerve cell populations after withdrawal of alcohol could be related to the deficient or incomplete functional recovery often seen after abstinence from alcohol.

P-480 - Changes of endogenous quinolinic acid and excitatory amino acid receptor in brain of phenobarbital -dependent and -withdrawn rats.

P-480 - Changes of endogenous quinolinic acid and excitatory amino acid receptor in brain of phenobarbital -dependent and -withdrawn rats.

Differential effects on GABA A receptor γ2-subunit messenger RNA by tolerance to and withdrawal from pentobarbital — an in situ hybridization study

The heterogeneity of the GABA A receptors has been confirmed structurally and functionally. The present study demonstrates the pharmacological heterogeneity of the GABA A receptors. Rats were rendered tolerant to pentobarbital by continuous intracerebroventricular infusion via osmotic minipumps and abruptly withdrawn from pentobarbital. In situ hybridization of mRNA coding for the GABA A receptor γ 2-subunit showed decreases of mRNA levels in superior and inferior colliculus in pentobarbital tolerant rats compared to rats in withdrawal. In rats 24-hr after withdrawal from pentobarbital, increases of mRNA levels in neocortex, piriform cortex and in granular and Purkinje cell layers of the cerebellum were observed. These results indicate the fast adaptation of GABA synapses in response to abrupt withdrawal from chronic pentobarbital treatment. The differential responsiveness seen in different areas further confirms the pharmacological heterogeneity of the GABA A receptors. The observed increases and decreases of mRNA may underlie, at least in part, the previously reported changes in Bmax of GABA A receptor ligand binding sites.

Quantification of tremor sensitivity and inhibition of exploratory behaviour during alcohol withdrawal in rats

Rats given a 10% (v/v) alcohol liquid diet over two weeks reached high blood alcohol levels of around 200mg/dl. Discontinuation of the alcohol intake resulted within 6h in several withdrawal reactions including a tremorogenic activity and a reduction in exploratory behaviour in novel environments. The tremorogenic activity of the alcohol withdrawal could be quantified, using a piezo-film technique, in terms of a supersensitivity to both an inactive and a moderately active dose of the tremorogenic compound harmine. As compared to controls, the rats in alcohol withdrawal revealed more frequent tremor after both 5 and 10mg/kg harmine. The supersensitivity to harmine-induced tremor started within 6h after alcohol withdrawal and remained present with 10mg/kg harmine for up to 48h. The supersensitivity was independent of the length of the tremor bursts used to quantify harmine-induced tremor. Alcohol withdrawal also resulted in an inhibition of exploratory behaviour in a neutral two-chamber box. Both in terms of the number of transits into the open field as well as the time spent in the open area, rats in alcohol withdrawal were significantly less active than control animals. The reduced exploration started within 6h after withdrawal and remained present for up to 24h after the last alcohol intake. These results indicate that both alcohol withdrawal-induced sensitivity to tremorogenic agents and inhibition of exploratory behaviour can be quantified over time, allowing the pharmacological mechanisms involved to be studied.

P-363 - Functional changes of the GABAB receptor in the brain of phenobarbital-dependent and withdrawn rats

P-363 - Functional changes of the GABAB receptor in the brain of phenobarbital-dependent and withdrawn rats

The influence of chronic captopril treatment and its withdrawal on endothelium-dependent relaxation.

The current experiments were designed to explore the relationship between the renin angiotensin system (RAS) and prostanoid formation in aortic ring preparations from spontaneously hypertensive rats (SHR). A further aim was to examine the mechanisms responsible for the reversal of the impaired acetylcholine (ACh) mediated relaxation induced by chronic administration of the angiotensin converting enzyme inhibitor captopril and the relationship of the ACh response to blood pressure. Rats were administered captopril (100 mg/kg/day) and their blood pressures monitored from 5 to 17 weeks of age. ACh-mediated relaxation was determined in aortic ring preparations from untreated and treated rats, and drug withdrawn rats. The influence of indomethacin, saralasin, SQ29548 and captopril on ACh-mediated responses was determined. It was found that chronic captopril treatment produced a marked suppression of the development of hypertension in the SHR. After the withdrawal of the drug the blood pressure remained significantly lower than in untreated animals for 4 weeks. ACh relaxation was impaired in SHR ring segments; this was reversed with captopril treatment and returned to the impaired state upon withdrawal of the drug. In vitro inhibition of the RAS did not significantly influence ACh relaxation. In contrast, impairment of the prostanoid system in vitro reversed the impaired relaxation. The results suggest that the influence of captopril on enhancing ACh relaxation in the SHR does not involve an acute interaction of local angiotensin II synthesis with prostanoid mechanisms. Importantly, the results highlight a dissociation between the impaired ACh relaxation and elevated blood pressure in the SHR.

The Effects of Piracetam on Lipofuscin of the Rat Cerebellar and Hippocampal Neurons after Long‐Term Alcohol Treatment and Withdrawal: A Quantitative Study

There is a growing body of evidence indicating that chronic alcohol consumption induces morphological changes in the central nervous system (CNS) similar to those observed during brain senescence, including an increased formation of lipofuscin. In addition, it was also found that alcohol withdrawal does not reverse these changes. On the contrary, most of the alterations observed during alcohol consumption worsen as happens with the increased lipofuscin formation. Thus, using our model of alcohol feeding and withdrawal, we decided to examine the effects of different drugs said to offer neuronal protection during CNS degenerative processes. The action of piracetam, a cyclic derivate of GABA and commonly used as a nootropic agent, was tested by studying the lipofuscin accumulation on the cerebellar Purkinje and hippocampal CA3 pyramidal cells in alcohol-treated and withdrawn rats. Piracetam was found to markedly decrease the formation of neuronal lipofuscin. Whatever the functional implications of this pigment, its reduction in piracetam-treated animals might be related either to a protective effect on the intraneuronal membranous system or to an antioxidant property of this molecule.

Time course of transient behavioral depression and persistent behavioral sensitization in relation to regional brain monoamine concentrations during amphetamine withdrawal in rats

This experiment was designed to characterize the withdrawal syndrome produced by discontiuation of treatment with escalating, non-neurotoxic doses of d-amphetamine (AMPH). AMPH withdrawal was associated with both transient and persistent changes in behavior and postmortem brain tissue catecholamine concentrations. During the first week of withdrawal rats showed a significant decrease in spontaneous nocturnal locomotor activity. This behavioral depression was most pronounced on the first 2 days after the discontinuation of AMPH pretreatment, was still evident after 1 week, but had dissipated by 4 weeks. Behavioral depression was not due to a simple motor deficit, because AMPH-pretreated animals showed a normal large increase in locomotion when the lights initially went out, but they did not sustain relatively high levels of locomotor activity throughout the night, or show the early morning rise in activity characteristic of controls. Behavioral depression was associated with the transient decrease in the concentration of norepinephrine (NE) in the hypothalamus, and a transient decrease in the ability of an AMPH challenge to alter dopamine (DA) concentrations in the caudate-putamen and nucleus accumbens. AMPH pretreatment also produced persistent changes in brain and behavior. The persistent effects of AMPH were not evident in spontaneous locomotor activity, but were revealed by a subsequent challenge injection of AMPH. AMPH pretreated animals were markedly hyper-responsive to the stereotypy-producing effects of an AMPH challenge. This behavioral sensitization was not fully developed until 2 weeks after the discontinuation of AMPH pretreatment, but then persisted undiminished for at least 1 year. It is suggested that the transient changes in brain and behavior described here may represent an animal analogue of the "distress syndrome" seen in humans during AMPH withdrawal, which is associated with symptoms of depression and alterations in catecholamine function. On the other hand, persistent behavioral sensitization may be analogous to the enduring hypersensitivity to the psychotogenic effects of AMPH seen in former AMPH addicts.

INTRACEREBRAL GRAFTING IMPEDES HIPPOCAMPAL CELL LOSS DURING WITHDRAWAL AFTER LONG-TERM ALCOHOL CONSUMPTION IN RATS

We previously found that, in the hippocampal formation as well as other central nervous system regions, withdrawal from alcohol following long periods of ingestion did not impede the ethanol-induced degenerative changes, including cell loss: on the contrary, neuronal degeneration was found to be increased in withdrawn rats. By grafting withdrawn rats either with immature hippocampal blocks or with suspensions of cultured astrocytes, we hoped to arrest the process of cell loss or even reverse it, because it is known that grafted material might display trophic and eventually protective effects in conditions of brain damage. The dentate granule and hippocampal CA3 pyramidal cells were counted both in the grafted hemisphere and in the contralateral one. Grafts of astrocyte suspensions did not interfere with the ongoing process of cell death in withdrawn rats. Conversely, grafts of hippocampal tissue impeded the degeneration observed in the granule and pyramidal cells of the grafted hemisphere, although in the contralateral one the cell loss persisted. We therefore conclude that the protective effect displayed by solid grafts might be a local process dependent on the release of diffusible trophic agents. We cannot explain the absence of any effect displayed by astroglial grafts, inasmuch as in different experimental situations such an effect was described.

Dependence and withdrawal following intracerebroventricular and systemic morphine administration: functional anatomy and behavior

Regional cerebral glucose utilization (RCGU) and behavior during precipitated morphine withdrawal were studied in rats made dependent by either intracerebroventricular (i.c.v.) or subcutaneous (s.c.) administration of morphine. [4C]2-deoxy-d-glucose autoradiography revealed that RCGU increased in an anatomically related group of limbic and brainstem structures in rats that were in morphine withdrawal precipitated by naloxone administration compared to morphine-dependent controls that were not in precipitated withdrawal. Correlation of RCGU for 24 brain structures comparing i.c.v. vs s.c. morphine-treated rats was highly significant for groups in withdrawal and for controls (r values, 0.958 and 0.971, respectively). Withdrawal behaviors including autonomic signs of withdrawal, withdrawal jumping, and incidence of diarrhea were not different between the two groups in withdrawal (i.c.v. and s.c.). Weight loss during withdrawal increased (P < 0.05) in rats made dependent by s.c. morphine administration compared to rats that received morphine by the i.c.v. route. Taken together, these results indicate that RCGU changes during morphine withdrawal result solely from effects of chronic morphine in the central nervous system, not in peripheral sites. The increased weight loss of s.c.-treated, morphine-dependent rats in withdrawal suggests an independent peripheral effect perhaps mediated by visceral opiate receptors.

Rats withdrawn from ethanol rapidly re-acquire membrane tolerance after resumption of ethanol feeding

The time course for the re-acquisition of membrane tolerance to the disordering effects of ethanol in vitro has been determined for liver microsomes obtained from chronically ethanol-fed rats that were withdrawn from ethanol for 2–4 days (during which tolerance is lost) followed by resumption of ethanol feeding. Naive rats require 28–35 days of chronic ethanol feeding to develop membrane tolerance. Microsomal membranes regain partial sensitivity to ethanol disordering after 2–3 days of withdrawal and regain the complete sensitivity observed in membranes from untreated control rats after 4 days of withdrawal. The period of ethanol re-feeding required for the reacquisition of membrane tolerance was dependent on the withdrawal period, with tolerance appearing sooner if the withdrawal period was shorter. The time course for the re-development of tolerance in previously tolerant animals was considerably faster (4–14 days) than in naive rats being administered the ethanol diet for the first time (35 days). Microsomes from rats that were withdrawn for 2 days (which retained partial tolerance) and then re-fed the ethanolic-diet required only 4 days to re-acquire membrane tolerance. Micrsomes from rats withdrawn 3 days required 8 days and those withdrawn 4 days required 15 days for full tolerance to re-develop. The same timecourse for the re-acquisition of membrane tolerance was observed in either intact microsomes or in liposomes prepared from extracted microsomal total phospholipids. Phosphatidylinositol (PI) has previously been reported to be responsible for conferring membrane tolerance to liver microsomes in ethanol-fed rats (Taraschi, T.F., Ellingson, J.S., Wu, A., Zimmerman, R. and Rubin, E. (1986) Proc. Natl. Acad. Sci. USA 83, 9398–9402). The time course for re-acquisition of membrane tolerance by liver microsomes following ethanol withdrawal and resumption of ethanol feeding correlated with the ability of PI to confer tolerance.

Paeker and Radow test of drug withdrawal aversion: Opposite effect in rats chronically infused with sufentanil or amphetamine

In rats, cessation of periodic injections of morphine reduces a preference for a palatable saccharin solution presented in a choice with water, and this has been interpreted to reflect withdrawal malaise. We confirmed and examined this “Parker and Radow Model” using subcutaneously implanted osmotic minipumps as the means of drug delivery and the opiate, sufentanil, and the psychostimulant, amphetamine, as the treatment drugs; surgical removal of the pumps was used to initiate withdrawal. Thus, rats withdrawn after 2 weeks exposure to a sufentanil-delivering pump (0.25 μg/hr) showed a decrease preference for the saccharin and animals exposed to an amphetamine pump (68 μg/hr) showed an increased preference, as compared to placebo-exposed controls. This pattern of effects was systematically replicated in new subjects using 4 weeks of treatment and 136 μg/hr amphetamine. Since the locomotor increasing and body weight decreasing effects of amphetamine were also demonstrated and the doses of amphetamine and sufentanil were in comparable dose ranges, it was concluded that the Parker and Rakow procedure may be a reliable measure of opiate withdrawal, but under similar test and treatment conditions other processes may be operative in amphetamine-treated animals. Problems of measuring motivation of withdrawal, particularly of spontaneous withdrawal, were noted.

Osmoregulation of vasopressin secretion in the insulin-withdrawn streptozotocin-treated diabetic rat.

To investigate whether hyperglycaemic ketoacidotic diabetic rats continue to osmoregulate the secretion of arginine vasopressin (AVP), male Wistar rats were injected with streptozotocin (150 mg/kg body weight). Rats rendered diabetic were maintained on protamine-zinc insulin (PZI) for 11 days (insulin-treated rats; n = 35), after which PZI was withdrawn for 72 h in half the rats (insulin-withdrawn rats). Insulin-withdrawn and -treated rats were divided into two groups; one was injected i.p. with distilled water (20 ml/kg) and the other with hypertonic saline (500 mmol NaCl/l; 20 ml/kg), and killed 30 min after injection. Insulin-withdrawn rats (water loaded and osmotically stimulated) were hyperglycaemic (16.5 +/- 0.8 and 16.5 +/- 0.9 mmol glucose/l respectively) and ketotic (2077 +/- 664 and 1474 +/- 170 mumol acetoacetate/l respectively). Insulin-treated rats were euglycaemic and non-ketotic. Osmotic manipulation caused similar changes in plasma sodium in both insulin-withdrawn and -treated rats. Plasma AVP was low in the water-loaded rats (0.6 +/- 0.1 and 4.5 +/- 0.9 pmol/l in the insulin-treated and -withdrawn rats respectively) and increased in rats injected with hypertonic saline (1.2 +/- 1.8 and 35.2 +/- 17.9 pmol/l respectively). There was no evidence of hypotension and hypovolaemia in any group of rats. Linear regression analysis defined the functions: plasma AVP = 2.56 (plasma Na-141), r = +0.63, P less than 0.01 for hyperglycaemic ketotic rats; plasma AVP = 0.83 (plasma Na-146), r = +0.78, P less than 0.001 for insulin-treated animals. The slopes and abscissal intercepts were significantly (P less than 0.05) different.(ABSTRACT TRUNCATED AT 250 WORDS)

P-207 - Characteristic changes of 3H-muscimol binding in phenobarbital-dependent and withdrawn rats

P-207 - Characteristic changes of 3H-muscimol binding in phenobarbital-dependent and withdrawn rats

Effects of Alcohol on Isoproterenol-Induced Ventricular Fibrillation in Adult Rats

To determine whether the pattern of alcohol consumption, intake, and withdrawal modulates the incidence of malignant ventricular arrhythmias and sudden cardiac death due to beta-adrenergic stimulation in a species susceptible to administration of isoproterenol alone, a regimen was formulated in which both continuous and interrupted alcohol ingestion was obtained. After alcohol treatment of fully mature, adult rats for 7 weeks, a single subcutaneous injection of 150 micrograms/kg of isoproterenol was given to control (non-alcohol-treated), alcoholic (continuous consumption), and alcohol withdrawal (interrupted) rats. The incidences of malignant ventricular arrhythmias and related deaths were compared. The results revealed that arrhythmias and arrhythmic deaths were highest in the "alcohol withdrawal group," 92% and 54%, respectively. As judged from baseline studies, withdrawal of alcohol produced a 16% decrease in serum K+ concentration compared with controls, whereas continuous alcohol ingestion resulted in a 20% elevation in magnesium concentration. These electrolyte changes were further affected by isoproterenol and may have contributed to the differential response to beta-adrenergic stimulation as a result of the pattern of alcohol intake.

Reversal of increased anxiety during benzodiazepine withdrawal: Evidence for an anxiogenic endogenous ligand for the benzodiazepine receptor

Rats were injected daily for 21 days with water or with chlordiazepoxide hydrochloride (10 mg/kg) and then tested in the elevated plus-maze 24–30 hr after the last of their chronic injections. At this time, rats withdrawn from chlordiazepoxide showed a significant decrease in the % of time spent on the open arms, compared with controls, thus indicating enhanced anxiety. The benzodiazepine antagonist, flumazenil (Ro 15-1788, 4 mg/kg, IP 20 min before test) significantly ( p < 0.01) reversed this withdrawal anxiety, and was without effect in the control group. The partial inverse agonist, FG 7142 (5 mg/kg IP 30 min before test) had no significant effect on the withdrawal anxiety. Possible mechanisms underlying the enhanced anxiety displayed by rats in withdrawal from chlordiazepoxide are discussed. It is concluded that a likely explanation is that chronic benzodiazepine treatment leads to an increased production and release of an endogenous ligand for the benzodiazepine receptor, with inverse agonist properties.

Diurnal changes in succinate and d-3-hydroxybutyrate dehydrogenase activities of rat liver mitochondria after chronic alcohol consumption and withdrawal

1. 1. The succinate dehydrogenase (SDH) and d-3-hydroxybutyrate dehydrogenase (HBDH) activities were measured over a 24-hr period in rat liver mitochondria after chronic alcohol ingestion and withdrawal. 2. 2. The diurnal patterns of both the enzyme activities were shown to change after alcohol consumption, with 64–66% decrease in the daily mean levels. 3. 3. The diurnal rhythms of the SDH and HBDH activities are partially restored 24–72 hr after alcohol withdrawal. 4. 4. There was no correlation between changes in both the enzyme activities and the NAD +/NADH ratio of liver mitochondria from control, ethanol-fed and withdrawn rats over the day.

Stress-induced immobility in rats with cholinergic supersensitivity

Immobility during forced swimming or after mild footshock (1 mA for 2 sec) was observed in five groups of rats. The Flinders Sensitive Line (FSL) of rats, known to be more sensitive to cholinergic agonists, exhibited the greatest degree of immobility in the forced swim test. Rats chronically treated with, and subsequently withdrawn from, either scopolamine (2 mg/kg, once daily) or amitriptyline (10 mg/kg, once daily) were also significantly more immobile than either a control group treated chronically with isotonic saline or the Flinders Resistant Line (FRL) of rats in the forced swim test. Similar trends were observed for locomotor depression in the open field following exposure to footshock. Receptor binding studies indicated significantly greater concentrations of muscarinic acetylcholine receptors in the hippocampus of the scopolamine, and amitriptyline, withdrawn rats. These findings indicate that rats with increased cholinergic sensitivity are more sensitive to the immobility-inducing effects of mild Stressors. Thus, they may prove to be useful models for studying the relationship between affective disorders and the cholinergic system.