Dopamine release during ethanol drinking in AA rats

The dopamine overflow in the nucleus accumbens of rats from the high alcohol drinking AA line was measured by microdialysis before, during, and after one-half hour sessions of cued drinking of ethanol flavored with saccharin and peppermint or, as a control, saccharin-peppermint drinking. The animals had had extensive previous experience with ethanol drinking. Self-administration of the ethanol solution did not raise the dopamine level substantially: there was a small (17%) but significant increase only during the first 10 min after the onset of drinking. Giving the rats a cue for ethanol, which was part of their daily routine drinking regime, did not raise the dopamine level before ethanol was presented to the rats (i.e., during "anticipation"). The results are consistent with our previous studies showing a lack of a large ethanol-induced dopamine response in rats with previous experience of drinking ethanol and with the idea that although dopamine may play some role in alcohol drinking, it is not the central substrate producing the reinforcement from ethanol in AA rats.     

Diurnal variation in plasma ethanol levels of TO and CBA mice on chronic ethanol drinking or ethanol liquid diet schedules

Data accumulated from epidemiological observations, intervention trials and studies on experimental animals provide a growing body of evidence of the influence of various dietary components on blood pressure. Dietary sodium, usually taken in the form of sodium chloride (common salt), is positively associated with blood pressure, and in many hypertensive patients reduction in sodium intake lowers blood pressure. On the other hand, in certain patients potassium, calcium and magnesium may be protective electrolytes against hypertension. Dietary fats, especially n-3 polyunsaturated fatty acids, may also influence blood pressure, whereas the possible role of other macronutrients, such as proteins and carbohydrates, or vitamins in the regulation of blood pressure is less well understood. Occasional ingestion of coffee transiently increases blood pressure, but the effects of habitual coffee consumption are controversial. Excessive use of alcohol on a regular basis has been associated with elevated blood pressure. It has also been shown in case reports that large amounts of liquorice lead to the development of hypertension. Thus, with appropriate dietary modifications, it is possible to prevent the development of high blood pressure and to treat hypertensive patients with fewer drugs and with lower doses. In some patients antihypertensive medication may not be at all necessary.     

Effect of naltrexone and its derivatives, nalmefene and naltrindole, on conditioned anticipatory behaviour and saccharin intake in rats

Drug craving, the desire to re-experience the effects of a psychoactive substance, may be an important influence on drug-seeking and drug-taking behaviour. In rats, drug-seeking behaviour can be operationalized as conditioned anticipatory behaviour, evidenced by frequent visits to, and an increased time spent and distance travelled in, the drug administration area prior to the availability of the reinforcer. The effects of the opioid antagonist, naltrexone, and its derivatives, nalmefene and naltrindole, on conditioned anticipatory behaviour and drinking-associated behaviour and fluid intake during the access phase were examined. Male Wistar rats were trained to consume 0.1% saccharin and water in a distinct environment in a free-choice limited-access procedure. Naltrexone (0.3, 1 mg/kg) decreased conditioned anticipatory behaviour and drinking-associated behaviour in the saccharin zone without affecting the corresponding behaviour in the water zone. Its derivatives had different effects. Nalmefene (0.1 mg/kg) increased drinking-associated behaviour but not conditioned anticipatory behaviour, whereas naltrindole (1, 2 mg/kg) modestly decreased conditioned anticipatory behaviour but not drinking-associated behaviour. Naltrexone (0.3, 1 mg/kg) and naltrindole (1, 2 mg/kg), but not nalmefene, selectively decreased saccharin intake. These findings suggest that the blockade of selective opioid receptors may differentially alter conditioned anticipatory behaviour, drinking-associated behaviour and consumption levels, and that these behaviours can be modified separately.     

Effect of administration and subsequent cessation of buserelin on cancellous bone of female rats

OBJECTIVE: Low-dose dopamine has been used in critically ill patients to minimize renal dysfunction without sufficient data to support its use. The aim of this study was to determine whether low-dose dopamine improves renal function, and whether dobutamine, a nondopaminergic inotrope, improves renal function. DESIGN: Prospective, randomized, double-blind trial. PATIENTS: Twenty-three patients at risk for renal dysfunction were entered into the study. Five patients were later withdrawn. Study data for the remaining 18 patients were: mean age 55 yrs; mean Acute Physiology and Chronic Health Evaluation (APACHE) II score of 18; mean weight 71 kg). The following conditions were present: mechanical ventilation (n = 17 [inverse-ratio ventilation, n = 6]); inotrope administration (n = 11); sepsis (n = 13); and adult respiratory distress syndrome or multiple organ failure syndrome (n = 9). INTERVENTIONS: The study patients were administered dopamine (200 micrograms/min), dobutamine (175 micrograms/min), and placebo (5% dextrose) over 5 hrs each in a randomized order. Ventilator settings, fluid management, and preexisting inotropic support were not altered during the study. MEASUREMENTS AND MAIN RESULTS: Systemic hemodynamic values and indices of renal function (4-hr urine volume, fractional excretion of sodium, and creatinine clearance) were measured during the last 4 hrs of each infusion. Dopamine produced a diuresis (145 +/- 148 mL/hr) compared with placebo (90 +/- 44 mL/hr; p < .01) without a change in creatinine clearance. Conversely, dobutamine caused a significant increase in creatinine clearance (97 +/- 54 mL/min) compared with placebo (79 +/- 38 mL/min; p < .01), without an increase in urine output. CONCLUSIONS: In stable critically ill patients, dopamine acted primarily as a diuretic and did not improve creatinine clearance. Dobutamine improved creatinine clearance without a significant change in urine output.     

Anxiogenic effect of naltrexone in social interaction test in rats

AIM: To study the anxiogenic effect of naltrexone (Nal) on the emotional state of rats. METHODS: The duration of active interaction was measured in the social interaction test in rats. RESULTS: Without influence on the locomotor activity, Nal (0.1-50 mg.kg-1) dose- and time-dependently decreased the duration of active interaction, which was antagonized by morphine (5 mg.kg-1) or fenclonine (Fen, 150 mg.kg-1 x 3 d) and was enhanced by 5-hydroxytryptophan (5-HTP, 50 mg.kg-1). CONCLUSION: Nal produced anxiety via its blockade of opioid receptors; central opioidergic neurons were involved in the regulation of anxiety through their tonic inhibitions in serotonergic neurons.     

Effect of consistency of reward during runway training on subsequent discrimination performance in rats.

Describes 2 experiments with male albino Holtzman rats (N = 64). In Exp. I, Ss were trained under partial (PR) or continuous (CR) reward in a gray or striped runway and were then trained on a simultaneous stripe-orientation discrimination. PR caused a decrement in discrimination performance after training in the striped runway but had no effect after training in the gray runway. In Exp. II, Ss received PR, CR, or no training in a runway with stripe cues on the floor of the runway varying randomly in orientation. All Ss were then trained on a simultaneous compound-cues discrimination with orientation and width of stripes relevant. After reaching criterion each S was given single-dimension tests on each dimension. PR Ss performed worse on orientation tests but not on width tests. Results are interpreted as supporting stimulus-analyzer theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibitory effects of naltrexone on the induction of parental behavior in juvenile rats

Juvenile rats are rapidly responsive to pups soon after weaning, displaying maternal-like behaviors such as licking, retrieving, grouping, and crouching over pups. As juveniles reach 30 days of age, they become less responsive to pups and show increased latencies to display the same parental behaviors. In light of previous data implicating opiates in the display of ongoing maternal behavior, we administered naltrexone, a long-acting opiate antagonist, beginning 5 and 9 days prior to and continuing throughout the period of behavioral testing, which started at 26 or 30 days of age. Male and female juveniles treated with 10 mg/kg of naltrexone SC for 9 days (days 21 to 29 of age) prior to and during behavioral testing (days 30 to 37) showed longer latencies to retrieve, group, and crouch over pups than did the vehicle-injected controls. These results suggest that opioids may have a stimulatory role in parental behavior during this prepubertal period.     

Effects of ethanol on Pavlovian autoshaping in rats

Approach responses, consummatory behaviors, and directed motor responses maintained by food reward resemble autoshaping CRs and are increased by lower doses of ethanol. This study evaluated the effects of presession i.p. injections of ethanol doses (0.00, 0.25, 0.50, 0.70. or 1.00 g/kg) on the acquisition of lever-press autoshaping CR performance in groups of male Long-Evans hooded rats. Paired groups received 15 daily sessions of Pavlovian autoshaping procedures, wherein the insertion of a retractable lever for 5 s (CS) was followed by the response-independent presentation of food (US). Ethanol facilitated lever-press autoshaping CR acquisition, as revealed by dose-related increases in the number of trials on which CRs were performed. The form of the dose-effect curve was inverted U-shaped with maximal responding induced during sessions 1-5 by the 0.70 g/kg ethanol dose. A similar dose-effect curve was observed during sessions 11-15, revealing that the effects of ethanol on autoshaping CR performance were relatively stable. A pseudoconditioning control group injected presession with 0.50 g/kg ethanol received training wherein the food US was presented randomly with respect to the lever CS. Few lever-presses were performed by the Random 0.50 group, indicating that ethanol's effects on autoshaping CR acquisition and maintenance observed in the Paired 0.50 group were not due to its psychomotor activating effects. A non-injection control group performed more autoshaping CRs than did the control group injected presession with saline, indicating that daily presession i.p. injections per se suppress autoshaping CR performance. Results reveal that low doses of ethanol enhance Pavlovian conditioning of directed motor and consummatory-like responding maintained by food reward. Implications for autoshaping accounts of impulsivity and drug abuse are considered.     

Oropharyngeal control of drinking in rats

Drinking was studied in water-deprived rats with chronic intragastric fistulas. Sham drinking, by which the ingested water was immediately lost through the open gastric fistula, was approximately four times greater than normal drinking. This proportion held across different levels of water deprivation, following 5-ml intragastric preloads of water or isotonic saline or ingestion of isotonic saline. The contribution of oropharyngeal controls in the normal drinking of rats is discussed and is compared with that of other species.     

Effects of naltrexone and signaling inescapable electric shock on nociception and gastric lesions in rats.

Two experiments, with 144 male Long-Evans hooded rats, examined the antinociceptive effects of signaled shock and its physiological underpinnings. In Exp I, Ss were exposed to 1 of 3 shock conditions: no shock, unsignaled shock, and signaled (by a 10-sec, 1,000-Hz tone) shock. In each condition, Ss were tested hourly in the absence of tones for nociception, with vocalization to shock used as the behavioral measure. Ss receiving signaled shocks had stomach ulcer scores intermediate between those of no-shock and unsignaled shock Ss. Signaled-shock Ss also displayed a pronounced vocalization antinociception effect. This suggested that signaled shock may be less aversive. Exp II investigated a possible role of endogenous opiate peptides in these effects. Ss received hourly injections of either the opiate antagonist naltrexone (7 mg/kg, ip) or saline. There were no significant effects of naltrexone on either stomach pathology or nociception scores. The same effects of signaled shock were obtained as in Exp I. It is concluded that the role of endogenous opiates in the effects of signaled shock seen here is minimal. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit priming of alcohol expectancy memory processes and subsequent drinking behavior.

Expectations about the effects of alcohol have been modeled as stored memories. This study tested the memory view for investigating the processes that influence drinking. Strategies taken from recent memory research were used to implicitly prime drinking. Consequent effects on consumption of a commercial nonalcoholic beer were measured. Participants were led to believe this beer contained alcohol. Eighty undergraduate women (n?=?20 per cell) participated in 2, apparently unrelated, studies. A 2?×?2 factorial design simultaneously varied videotaped primes (bar setting or neutral video) with semantic primes (expectancy or neutral words). Women exposed to unobtrusive alcohol primes of either type drank significantly greater amounts (p?     

Influence of ethanol on the pentylenetetrazol-induced kindling in rats

The effects of ethanol on the development of pentylenetetrazol (PTZ)-kindling as well as on fully PTZ-kindled convulsions in rats were investigated. Ethanol (0.5, 1.0 and 1.5 g/kg i.p.) administered 15 min prior to each PTZ-injection (35 mg/kg i.p.; 3 times/week) significantly inhibited the progressive seizure development compared to saline-treated controls. For the higher doses of ethanol the kindling process was restricted to seizure stages of 1 or 2. Tolerance to this antiepileptogenic action did not occur even after 20 PTZ-stimulations. In a second series of experiments, 0.5 g/kg ethanol administered 10h before each PTZ-injection facilitated the rate of kindling development after 7 to 10 PTZ-injections, while the higher doses of ethanol did not modulate or even slightly reduced the seizure development. In a third test, intermittent administration of a high dose of ethanol (2 g/kg p.o.; twice daily for 6 days) before the kindling procedure (0.5 g/kg i.p. ethanol 10h prior to each PTZ-injection), significantly intensified the kindling development. In addition, studies with fully PTZ-kindled rats demonstrated that ethanol (0.1 to 1.5 g/kg i.p.), given 15 min prior or 2 min after PTZ, reduced the seizure severity in a dose-dependent manner. In conclusion, the present findings provide evidence for pronounced antiepileptogenic and anticonvulsant effects of ethanol after acute application, whereas repeated administration of high doses with longer withdrawal periods leads to proconvulsant actions, possible mediated via neuroadaptive changes in NMDA and/or GABA(A) receptor-related mechanisms.     

The effect of gestational ethanol exposure on voluntary ethanol intake in early postnatal and adult rats.

Clinical and epidemiological studies provide strong data for a relationship between prenatal ethanol exposure and the risk for abuse in adolescent and young adult humans. However, drug-acceptance results in response to fetal exposure have differed by study, age at evaluation, and experimental animal. In the present study, the authors tested whether voluntary ethanol intake was enhanced in both the infantile and adult rat (15 and 90 days of age, respectively), as a consequence of chronic fetal drug experience. Experimental rats were exposed in utero by administering ethanol to a pregnant dam in a liquid diet during gestational Days 6-20. Compared with those for isocaloric pair-fed and ad lib chow control animals, the results for experimental animals demonstrated that fetal exposure significantly increased infantile affinity for ethanol ingestion without affecting intake patterns of an alternative fluid (water). Heightened affinity for ethanol was absent in adulthood. Moreover, the results argue against malnutrition as a principal factor underlying the infantile phenomenon. These data add to a growing literature indicative of heightened early postnatal acceptance patterns resulting from maternal use or abuse of ethanol during pregnancy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of different postnatal periods of protein-energy malnutrition in young rats upon subsequent protein utilization

Previously it had been shown that rat pups, malnourished during the 3-week suckling period and the nutritionally rehabilitated for about 30 weeks, showed an increase in the efficiency of dietary protein utilization of the protein was fed at a less than optimal level and if the protein was of poor nutritional quality (J. Nutr. 103, 273, 1973). The present study extends this observation to growing rats malnourished during the first 3 weeks of life and then rehabilitated with a 25% casein diet for 4 weeks. The test proteins were casein, fed at a level of 12%, and wheat gluten, at a level of 25%. Efficiency of nitrogen retention was greater for both proteins in rats previously malnourished than for control, non-malnourished rats. Malnutrition was then imposed on rats malnourished by feeding a low protein diet either during the first 4 weeks postweaning or from the 7th to 11th week of life. After these periods of malnourishment, the rats were rehabilitated for 4 weeks and efficiency of utilization measured for both casein and wheat gluten fed at 10% of the diet. No change in utilization was found for either protein fed to rats rehabilitated from either of these periods of malnutrition.     

Effect of intravenous administration of apolipoprotein A-IV on patterns of feeding, drinking and ambulatory activity of rats

To characterize the anorectic effect of apolipoprotein A-IV (apo A-IV), we examined the effect of apo A-IV on the patterns of feeding, drinking and ambulation of rats fed ad libitum. A single dose of 200, 135 or 60 micrograms was infused intravenously through a chronically indwelling right atrial catheter just before the dark period. Apo A-IV suppressed food intake by decreasing meal size, but did not affect the interval between meals, the speed of eating, or the latency to eat the first meal after infusion. The anorectic effect of apo A-IV was dose-dependent and was effective for about 3 h after the infusion. The anorectic effect of apo A-IV is specific because inactivation of apo A-IV abolishes its anorectic effect. The anorectic effect of apo A-IV is not shared by apo A-I. Apo A-IV had no effect on drinking behavior or ambulatory activity. The results seem to indicate that apo A-IV specifically decreases the meal size, which supports our hypothesis that apo A-IV may act as a physiological signal for satiation after the ingestion of a lipid meal.     

Differential effects of ethanol in adolescent and adult rats

Alcohol use in children and adolescents is widespread. However, very little is known about the effects of alcohol exposure during this period of postnatal development. The goal of the present study was to compare the relative sensitivity to the sedative effects of alcohol in periadolescent and adult rats. After treatment with either 4 or 5 g/kg ethanol, both 20- and 30-day-old rats regained their righting reflex significantly earlier than 60-day old rats. In 30-day-old rats, serum ethanol concentrations (SECs) were significantly greater at the time of the recovery of the righting reflex than 60-day-old rats. Developmental differences in the effects of ethanol on locomotor activity were also observed. In 60-day-old rats, 2.5 g/kg ethanol generally decreased locomotor activity. Ethanol did not significantly alter locomotor activity in 20- and 30-day-old rats. Finally there were significant developmental differences in the pharmacokinetics of ethanol with a significant delay in the time to peak SECs in 60-day-old rats relative to 20- and 30-day-old rats. These findings indicate that peri-adolescent rats are less sensitive to the sedative effects of ethanol as they recovered their righting reflex earlier and at significantly higher SECs than adult rats.     

Effects of ethanol on nonspatial working memory and attention in rats.

Investigation into the neural basis for ethanol-induced cognitive dysfunction requires the use of valid animal models. An operant signal detection procedure was developed to assess simultaneously the processes of sustained attention and working memory in rats, and to determine the effects of ethanol on these cognitive functions. Ethanol, at 0.75 g/kg intraperitoneal/ly (ip), produced delay- and stimulus length-dependent decreases in choice accuracy, effects that are consistent with deficits in both working memory and sustained attention. Local infusion of ethanol directly into the medial septal area resulted in a selective loss of choice accuracy at the long delay. The impairment by intraseptal ethanol did not interact with stimulus length. Thus, the working memory impairment, but not the decrement in sustained attention, was mimicked by intraseptal ethanol. The current model provides a foundation for studying the neural basis of ethanol's cognitive effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of drinking behavior in preweanling rats.

Studied the development of drinking behavior in 3–20 day old Sprague-Dawley rats by tracing their ability to perform progressively more complex components of the drinking act. Even 3-day-old Ss responded to cellular dehydration by actively swallowing intraoral infusions of milk and water or by licking these fluids when they were spread in a thin film across the floor of the test container. Ss were not able to approach and maintain contact with a distant fluid source until 10–25 days of age. By 20 days of age, dehydration reduced the consumption of milk and other types of food (dehydration anorexia). Results show that young Ss were able to respond to dehydration in a manner that resembled the adult response. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)