Search PubMed⌕ Search

Biomedical subjects

J A Engel

Publications and source records attributed to J A Engel.

80 records · Page 5Linked to original sources
PubMedDate not supplied

Effect of ethanol on ascorbate release in the nucleus accumbens and striatum of freely moving rats.

An in vivo voltammetry technique was used to monitor the extracellular ascorbate (AA) concentration in the nucleus accumbens and striatum of unanesthetized, freely moving rats. A single injection of ethanol, 1.0 g/kg intraperitoneally (IP), induced a significant increase in extracellular AA concentration in both the nucleus accumbens and striatum. This effect was dose dependent within a dose range from 0.5-2.0 g/kg. 4-Methylpyrazole (50 mg/kg, IP), which inhibits alcoholdehydrogenase, could not prevent the increase in AA concentration, evoked by ethanol. Furthermore, systemic administration of acetaldehyde (20 mg/kg, IP), the main metabolite of ethanol, did not have any effect on the level of AA in the nucleus accumbens or striatum. These results show that ethanol can alter the brain extracellular AA levels and that this effect seems to be attributed to ethanol itself and not to acetaldehyde. Consequently, these results indicate that a role for AA in the action of ethanol in the brain should be considered.

Animals↗
PubMedDate not supplied

Involvement of the serotonergic system in ethanol intake in the rat.

A two-bottle, free-choice paradigm was used to investigate the influence of the serotonergic (5-HT) system on ethanol intake in genetically heterogeneous Wistar rats. Systemic administration of the 5-HT1A agonist ipsapirone (1.25-5.0 mg/kg) caused a dose-dependent decrease in ethanol preference and intake, while the 5-HT2 antagonist ritanserin (1.25-5.0 mg/kg) and the 5-HT3 antagonists ondansetron (0.01-1.0 mg/kg) and granisetron (0.5-1.0 mg/kg) failed to alter ethanol consumption. The effect of ipsapirone treatment on ethanol intake was more pronounced in high-preferring animals than in low-preferring. A closer look at the microstructure of the rat's drinking behaviour by means of a microcomputer-controlled data acquisition system showed that ipsapirone treatment caused a significant decrease in the number of licks recorded at the ethanol-containing bottle and a decrease in the time spent at this bottle. Furthermore, ipsapirone treatment caused a significant increase in the number of breaks in licking behaviour recorded at this bottle. The drinking behaviour at the water-containing bottle was not affected by the ipsapirone treatment. Neither was the rat's eating behaviour altered by this treatment. These findings support the hypothesis that the 5-HT system is involved in the regulation of ethanol intake, with special emphasis on the involvement of the 5-HT1A receptor subtype, and may indicate that central reward-mediating mechanisms are influenced.

Alcohol Drinking↗
PubMedDate not supplied

Involvement of corticosterone in the modulation of ethanol consumption in the rat.

Several studies report that rats exposed to stressful conditions may increase their ethanol consumption. Stress is accompanied by a rise in the secretion of adrenocortical hormones, and the possibility that these hormones exert an influence on ethanol consumption should be considered. The present investigation addressed this issue by studying the effect of adrenalectomy (ADX) and subsequent corticosterone (CORT) or aldosterone (ALDO) treatment on ethanol intake. The results showed that ADX rats decreased their ethanol intake compared to the sham-operated controls and that treatment with CORT restored the intake of ethanol to the preoperative level. In contrast, treatment with ALDO (0.25 or 0.75 mg/kg) had no effect on ethanol intake. Biochemical analyses showed increases in monoamine turnover in the brain stem and limbic forebrain after ADX. The reduction of ethanol consumption caused by ADX may thus be specifically attributed to the loss of one of the adrenal hormones, CORT. The results indicate that CORT may be a factor of importance in the modulation of alcohol consumption.

Adrenalectomy↗
PubMedDate not supplied

5-HT1A receptor agonists reduce ethanol-induced locomotor activity in mice.

Animal studies as well as clinical studies have suggested that the brain 5-HT system is important for the regulation of voluntary ethanol intake and preference. Previous studies have suggested that 5-HT1A receptor agonists may reduce ethanol preference in rats. In the present study on mice, the 5-HT1A receptor agonists (8-OH-DPAT), ipsapirone, and buspirone all antagonized the locomotor activity (LMA) stimulatory effect of ethanol (2.5 g/kg). The present results provide further support for the notion that the LMA-increasing effect of ethanol may be homologous to its reinforcing properties and that 5-HT1A receptor agonists may counteract these properties as well.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMedDate not supplied

Taste reactivity to ethanol in rats: influence of adrenalectomy or ipsapirone.

The affective mimetic responses of male Wistar rats with prior access to 6% ethanol in their home cages were observed during intraoral infusions of an equivalent alcohol solution. Ethanol preference in the home cage appeared unrelated to measures of aversion and ingestion in the taste reactivity tests in normal rats. Adrenalectomy, which significantly reduced home cage ethanol preference, failed to influence the taste reactions elicited by ethanol or water. On the other hand, treatment of intact rats with the 5-HT1A receptor agonist ipsapirone (2.5 mg/kg), a drug that also decreases ethanol drinking in two-bottle intake tests, did increase the duration of aversive groomings, whereas measures of ingestion remained unaffected. These results suggest that ipsapirone, but not adrenalectomy, may alter the palatability of ethanol; this perceptual change may partly underlie the ability of ipsapirone to reduce home cage alcohol drinking in the rat.

Adrenalectomy↗
PubMedDate not supplied

Amphetamine-induced hyperactivity: differences between rats with high or low preference for alcohol.

This study determined the relationship between ethanol intake and spontaneous and amphetamine-induced locomotor activity. Locomotion was studied in high-preferring (HP; > 70% of total fluid intake consumed as alcohol) and low-preferring (LP; < 20% of total fluid intake consumed as alcohol) male Wistar rats with free access to water and a 6% (v/v) ethanol solution for 3 weeks. Following an alcohol-free 3-week period, the animals were tested for spontaneous motor activity for 1 h. One week later, locomotion was recorded in the same activity boxes following a subcutaneous injection with d-amphetamine sulfate (1 mg/kg). For determination of plasma levels of corticosterone, blood samples were taken immediately after each of the two tests for locomotor activity. There was no difference between HP and LP rats with regard to spontaneous locomotor activity. Neither were there any differences in plasma levels of corticosterone between the groups. Amphetamine stimulated locomotion in both HP and LP rats, but to a significantly greater extent in HP animals. Both groups had higher blood levels of corticosterone after the amphetamine test than after the drug-free test, but the corticosterone increase was significantly larger in the HP than in the LP rats. These data indicate that the same neural substrate (e.g., the mesocorticolimbic dopamine system) may mediate important aspects of both ethanol drinking and amphetamine responsiveness. Individual differences in the properties of this substrate may account for the finding that ethanol drinking and amphetamine responsiveness covary. A possible explanation for this association may be that prior consumption of ethanol sensitizes the neural substrate responsible for amphetamine-induced hyperactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Drinking↗
PubMedDate not supplied

A longitudinal study of the validity of parental reporting in the detection of otitis media and related hearing impairment in infancy.

A total of 150 full-term and 66 pre-term infants were selected at birth and prospectively examined at three-monthly intervals from birth until the age of 27 months. Parental reports of middle ear infection and/or hearing impairment were obtained prior to otoscopic and audiometric evaluation. The relationships between parental reports and the diagnoses acute otitis media (AOM), otitis media with effusion (OME) and hearing impairment (HI), were assessed in terms of sensitivity, specificity and positive and negative predictive values, using the data obtained during the follow-up period. AOM and OME were diagnosed using otoscopy and tympanometry. Hearing was assessed by conditioned orientation reflex audiometry. HI was defined as averaged thresholds > or = 20 dB compared with age-appropriate response levels. Despite the repeated feedback which parents received on the middle ear condition and hearing of their infants, the majority fail to recognize the presence of AOM, OME and HI. The limited sensitivity of parental reporting should discourage both researchers and clinicians from using it as a diagnostic or monitoring instrument, but they should not disregard parental concern when confronted with it.

Acoustic Impedance Tests↗