Sensitization to 5-HT1C receptor agonist in rats observed following withdrawal from chronic ethanol

Anxiogenic action of m-chlorophenylpiperazine (mCPP), a 5-HT1C receptor agonist, was studied in naive rats and in ethanol-tolerant rats following withdrawal from chronic ethanol administration. The purpose of this investigation was to determine whether a sensitization to mCPP develops during withdrawal from chronic ethanol. Male Long-Evans hooded rats were fed a liquid diet containing 4.5% ethanol or dextrin (as control) for four days. Twelve hours (acute withdrawal) or 4 days (protracted withdrawal) after the last dose of ethanol, rats were injected with saline or mCPP (0.08-5.0 mg/kg) and were tested in the elevated plus-maze 15 min postinjection. A reduction in percent open-arm activity, indicative of anxiogenic behavior, was observed in ethanol-treated rats injected with saline. Administration of mCPP further reduced the percent open-arm entries and time in ethanol-withdrawn rats. An eightfold reduction in maximum effective dose of mCPP was observed during acute ethanol withdrawal as compared to that in naive rats. During protracted ethanol withdrawal the maximum effective dose of mCPP was reduced by 75%. A shift of the mCPP dose-response curve to the left following withdrawal from chronic ethanol may indicate that 5-HT1C receptor sites are more sensitive to the activation by an agonist. This effect may be exploited in developing specific 5-HT1C receptor antagonists for the treatment of ethanol withdrawal symptoms.

Potential role of 5HT1C and/or 5HT2 receptors in the mianserin-induced prevention of anxiogenic behaviors occurring during ethanol withdrawal

A single dose of mianserin (a 5HT1C/5HT2 antagonist), administered 1 hr, 48 hr, or 7 days before testing, was evaluated for its efficacy in alleviating or preventing the occurrence of anxiogenic behaviors observed during ethanol withdrawal. Other behavioral experiments using selected drug interactions were conducted to examine whether the effect of mianserin was related to a long-term modification of 5-hydroxy-tryptamine (5HT) receptor function. Rats were fed a liquid diet containing 4.5% ethanol for 4 days. They were tested on the elevated plus-maze (EPM) 12 hr (acute withdrawal) and 5 days (protracted withdrawal) after the last ethanol dose. Ethanol withdrawal induced a pattern of "anxiogenic" behavior that consisted of reduced activity (total entries) and a reduced proportion of open arm activity. Mianserin, injected as a single dose given either 1 hr (0.16-5 mg/kg, ip) before testing or given (20 mg/kg, ip) on the morning of the 3rd day of ethanol administration, i.e., 48 hr and 7 days before testing, dose-dependently prevented or reversed the ethanol withdrawal induced reduction in open-arm activity. In contrast, the 5HT1C/5HT2 receptor agonist (+/- )-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl (DOl) did not affect behaviors in the EPM in ethanol-naive rats, nor in those undergoing ethanol withdrawal. However, although there was a marked tolerance to DOl-induced body shakes (a measure of 5HT2 function) during withdrawal, DOl reversed the action of mianserin in the EPM. The 5HT1 receptor agonist, 5HT2 receptor antagonist 1-naphthyl-piperazine (1-NP) reduced open-arm activity in ethanol-naive rats and this action was enhanced during withdrawal.(ABSTRACT TRUNCATED AT 250 WORDS)

Conflicting evidence regarding the efficacy of ondansetron in benzodiazepine withdrawal

These experiments tested the efficacy of the 5-hydroxytryptamine3 antagonist ondansetron (OND) in reversing various aspects of benzodiazepine withdrawal in rats. Three tests were used in which the benzodiazepine antagonist flumazenil was administered to rats receiving chronic administration of chlordiazepoxide. In one test, the elevated plus-maze, flumazenil produced a reduction in time spent in the open arms of the maze; OND completely reversed this effect of flumazenil in a dose-related fashion. However, OND failed to block the effects of the anxiogenic drug pentylenetetrazole (PTZ) in the elevated plus-maze. In a second test, rats were trained to discriminate PTZ. After chlordiazepoxide, flumazenil substituted for PTZ; OND failed to block flumazenil. In a third test, rats maintained on a chronic base line of chlordiazepoxide were trained to discriminate flumazenil from vehicle. In this discrimination, PTZ substituted for flumazenil, and pentobarbital blocked the flumazenil stimulus; OND, however, failed to block the flumazenil stimulus. In a separate set of experiments, OND also failed to reverse the suppression of responding produced in a conditioned emotional response paradigm. Thus, some data from the elevated plus-maze are consistent with the hypothesis that benzodiazepine withdrawal shares common effects with other stimuli known to be anxiogenic, and that OND blocks this aspect of withdrawal. However, all other data are inconsistent with the hypotheses that OND is anxiolytic or has efficacy in reversing benzodiazepine withdrawal. We suggest that ondansetron is likely to have minimal efficacy in humans for the treatment of sedative-hypnotic withdrawal.

Detection of antibodies to phenolic glycolipid by ELISA in leprosy patients

Antibody (IgM) response to PGL-1, a surface glycolipid unique to Mycobacterium leprae has been studied in 25 cases each of lepromatous and tuberculoid leprosy and in 25 healthy controls. The absorbance value at 488 nm was expressed as antibody titre. Serum antibody titre was found to be significantly higher in patients than controls. Results confirm that antibody response in leprosy patients depend upon bacterial load.

Anxiogenic effect of disulfiram evaluated in an animal model

The present experiment was designed to determine whether disulfiram produced an interoceptive discriminative stimulus (IDS) in rats similar to that exhibited by the anxiogenic drug pentylenetetrazol (PTZ). Rats were trained to discriminate PTZ (20 mg/kg IP) from saline, according to an FR10 schedule of food reinforcement. After training criteria had been met, discrimination testing revealed that disulfiram (100 mg/kg, IP) produced a PTZ-like IDS that fully substituted for PTZ 4 hours after injection, decaying to baseline values by the third day. The metabolite of disulfiram, diethyl dithiocarbamate (100 mg/kg, IP), followed much the same temporal pattern, but only showed partial substitution for PTZ. When ethanol (1 g/kg, gavage) or the monoamine oxidase inhibitor pargyline (50 mg/kg, IP) were administered in combination with disulfiram, no significant change of the PTZ-like stimulus was observed. Pargyline (100 mg/kg, IP) or acetaldehyde (200 mg/kg, IP), given alone, did not significantly substitute for PTZ. These data show that disulfiram produces an IDS in rats similar to that produced by other anxiogenic drugs. These data also suggest that the mechanism by which disulfiram produces its anxiogenic effect may not be entirely based upon the disulfiram metabolite diethyl dithiocarbamate, elevated acetaldehyde levels or stimulation of the catecholaminergic system.

Serum immunoglobulin E levels in children with chronic tonsillitis

Serum immunoglobulin E (IgE) levels were estimated by ELISA in 50 children with chronic tonsillitis before and after tonsillectomy. When compared with the control group, mean serum IgE concentration was found to be significantly higher in children with chronic tonsillitis (P less than 0.001). After tonsillectomy the levels returned to normal.

Within-subject behavioral analysis of recent memory in aging mice

Two experiments addressed the utility of a T-maze, delayed reversal paradigm for assessment of recent memory impairment in aging C57BL/6NNia mice. This paradigm involved acquisition of a learning set for identification of the correct arm choice in a daily multiple-trial discriminated avoidance session. During each session, the correct arm was always opposite that entered on an initial "information trial" and maximal performance thus required a reversal (or "lose-shift") strategy. Once the learning set had been acquired, retention performance was examined following delays of varying length which were introduced following the information trial during each session. In the first experiment, acquisition and retention components of delayed reversal were considered in a cross-sectional study involving separate groups of mice aged 7, 10, 15, or 27 months. Analysis of acquisition components suggested that relative to young mice, the old mice were slower to acquire both the first reversal and the learning set. Analysis of the retention phase suggested that memory decay gradients for goal arm discrimination became more pronounced with increasing age, whereas decay gradients for the avoidance response were similar among the age groups. Correlational analysis of data for the old mice suggested independence of age-related deficits in the acquisition and recent memory components of the delayed reversal paradigm. In the second experiment, survivors from the previous 7- and 10-month-old groups were retested when 27 months of age. The cross-sectional and longitudinal data led to the same conclusions with regard to the effect of age on recent memory function. Overall, these results suggest that the delayed reversal paradigm will be a valuable tool in the analysis and evaluation of interventions potentially affecting age-related cognitive impairment.

Detection of Chlamydia trachomatis antigen by enzyme immunoassay in patients with pelvic inflammatory disease

In 27 out of the 60 women clinically suspected to have pelvic inflammatory disease (PID) studied, the C. trachomatis antigen titre was found to be higher than the cut-off value. Since the presence of C. trachomatis antigen was detected in 45 per cent of women, it is suggested that all the PID patients may be investigated by ELISA to confirm the role of C. trachomatis as the etiological agent.

Learning and memory-enhancing effects of Ro 15-4513: a comparison with flumazenil

Synthetic benzodiazepines produce an anterograde amnesia, which can be reversed by selective benzodiazepine antagonists or inverse agonists. It has therefore been suggested that the memory-enhancing effects of the antagonists are due to antagonism of an endogenous "benzodiazepine-like" endocoid. If the memory-enhancing effects of the benzodiazepine antagonists are determined predominantly by the antagonism of such endogenous benzodiazepine-ligands, then it could be hypothesized that administration of an inverse agonist, which produces effects functionally opposite to those of benzodiazepine agonists, may also mimic the effects of benzodiazepine antagonists but not produce effects greater than those of the pure antagonists. The purpose of the present study was therefore to investigate the memory-enhancing effects of the benzodiazepine inverse agonist, ethyl-8-amido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo [1,5a] [1,4] benzodiazepine-3-carboxylate (Ro 15-4513) in young HSD:(ICR)BR mice and to compare these effects with those of the benzodiazepine antagonist, flumazenil. Pretraining injections of flumazenil and Ro 15-4513 (2.5 and 10.0 mg/kg) enhanced equally, both the acquisition and the retention of a task for 1 week requiring mice to discriminate the correct arm of a T-maze, to avoid a mild electric shock. Pretreatment with Ro 15-4513 also dose-dependently protected the animals from experimental amnesia, induced by the cholinergic receptor antagonist, scopolamine in a second model of memory, in which mice were required to passively avoid a dark chamber after shock. In contrast, Ro 15-4513, injected prior to daily active avoidance sessions, failed to significantly improve either the acquisition or retention performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Protracted withdrawal: sensitization of the anxiogenic response to cocaine in rats concurrently treated with ethanol

Rats were trained to respond on one lever following an injection of saline and the alternate lever after the anxiogenic drug pentylenetetrazol (PTZ 20 mg/kg), according to a fixed ratio (FR10) schedule of food reinforcement. The trained animals were then administered dependence-producing regimens of either cocaine (20 mg/kg, [IP], three times daily for 7 days) or ethanol (mixed 4.5% w/v with sweetened liquid diet given for 5 days). Separate groups of trained rats were given either subthreshold regimens of cocaine (20 mg/kg, IP, three times daily for 5 days), ethanol (2.25% w/v of the diet given for 5 days), or both. Additional groups were matched for control groups. After discontinuation of these regimens, rats were administered test injections of either saline or cocaine, and tested for elicitation of the PTZ-stimulus at selected intervals of withdrawal. After a saline injection, maximum elicitation of the PTZ-stimulus was observed 12 hours following chronic treatment with the higher dose of ethanol, and 120 hours following longer treatment with cocaine. During those periods of withdrawal when a saline injection failed to produce a PTZ-like stimulus, a test injection of cocaine (10 mg/kg) elicited the PTZ-stimulus in the ethanol withdrawn rats, although only partially eliciting the PTZ-stimulus in the cocaine withdrawn group. In the pair-fed controls, or rats withdrawn from the smaller dosage of either ethanol or cocaine, the test dose of saline or cocaine did not elicit the PTZ-stimulus; only 30% of rats selected the PTZ-appropriate level at the highest dose of cocaine tested (10 mg/kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of adenosine and inosine on carbon tetrachloride-induced liver damage in rats

Liver damage induced in rats by carbon tetrachloride (CCL4) was obvious macroscopically as well as microscopically in stained sections. Levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and gamma glutamyl transpeptidase (gamma-GT) were also significantly raised. Adenosine and inosine effectively countered the damage when these were given before and during the period during which CCl4 produces the typical damage. The beneficial effect was seen in biochemical as well as pathological studies.

Anxiogenic behavior in rats during acute and protracted ethanol withdrawal: reversal by buspirone

This study investigated the effectiveness of buspirone in reversing the anxiogenic behaviors occurring during ethanol withdrawal as measured in the elevated plus-maze. In response to anxiogenic drugs, rats spend less time in and make fewer entries onto the open arms of an elevated plus-maze, whereas anxiolytic drugs produce opposite effects. In this study, rats were fed a liquid diet containing 4.5% ethanol for 7 days. Twelve h (acute withdrawal) and 7 days (protracted withdrawal) following cessation of the ethanol diet, rats were tested on the elevated plus-maze. During these withdrawal periods, the percent open-arm entries and time spent on the open arms were significantly reduced relative to animals fed an ethanol-free diet, suggestive of anxiogenic-like symptoms. Buspirone (0.32-1.25 mg/kg) dose dependently reversed the withdrawal-induced decreases in open-arm activity. The anxiolytic-like activity of buspirone observed during ethanol withdrawal may be due to a reduction in serotonergic neurotransmission through activation of presynaptic 5-HT1A autoreceptors. The results obtained in this study suggest that pharmacotherapy with selective 5-HT1A agonists may be beneficial in alleviation of anxiety during ethanol withdrawal.

Tear lysozyme levels in bacterial, fungal and viral corneal ulcers

Low levels of tear lysozyme were observed in patients with infective corneal ulcers, when compared with controls. Lowest levels were seen in patients with bacterial corneal ulcers. The levels of tear lysozyme showed a corresponding decrease with the increase in Schirmer test values; meaning thereby, that in ocular conditions associated with increased rate of tear flow, the lysozyme content in tears tends to be low.

Immunoglobulins IgG, IgM and IgA levels in preterm and small for date newborns

Forty preterm [14 small for gestational age (SGA), 26 average for gestational age (AGA)] and 40 term (10 SGA and 30 AGA) babies were tested for immunoglobulins (Ig), G, M and A levels. IgG levels increased with gestational age from 922.00 +/- 14.00 mg/dl at 34 weeks to 1827.33 +/- 184.09 mg/dl at 40 weeks. Mean immunoglobulins were lower in SGA babies. IgG was 1029.59 +/- 122.80 mg/dl in SGA preterm babies and increased to 1262.00 +/- 200.0 mg/dl in 2 kg babies. IgM and IgA although increased with higher birth weight but rise was not statistically significant. More care to avoid infections in preterm and SGA babies, with lower immunoglobulin levels and less resistance, is recommended.

Effects of feeding low protein diet with and without leucine supplementation on protein status of lactating females and their pups

Female rats were fed low protein diet (10% casein) either as such or supplemented with 3% leucine during pregnancy and lactation. Changes in litter size and the survival rate, growth and protein status of the pups were noted. The milk yield and hepatic and mammary gland protein status of the mothers were also studied. Feeding low protein diet reduced litter size, increased their mortality and resulted in poor growth of the pups. It also resulted in poor hepatic and mammary gland protein status of the mothers, as well as reduced their milk yield. On adding 3% leucine to 10% casein in the diet, the changes observed in the low protein group, did not alter in any manner.

Exercise does not modify spatial memory, brain autoimmunity, or antibody response in aged F-344 rats

Old F-344 rats were given endurance training over a 10-week period on a motorized treadmill. This treatment resulted in substantial heart-to-body weight ratio increases, indicative of effective training. To determine whether endurance training might alter some of the known immune system and cognitive changes observed during aging, exercised old rats were compared to nonexercised old and young controls on three variables: in vivo antigen-specific immune activity, brain-reactive antibody formation, and spatial memory. The exercise training did not influence any of these measures in the old rats. Both groups of old rats showed poorer antibody response to a specific antigen, more brain-reactive antibody formation, and poorer spatial memory than the young controls. There was, however, a significant relationship between brain-reactive antibody formation and spatial memory performance, regardless of training condition.

Modulation of benzodiazepine agonist and inverse-agonist receptor binding by GABA during ethanol withdrawal

1. The present study examined the capacity of GABA to modulate flunitrazepam and Ro15-4513 binding to putative GABAA receptors. Binding was measured in distinct brain regions both before and during selected periods of withdrawal from ethanol. 2. Rats were fed a nutritionally complete liquid ethanol (4.5% w/v) diet for 4 days and at various times after the last dose of ethanol (0, 12, 24, & 72 hr), rats were sacrificed and extensively washed brain membrane fractions were prepared. 3. Competitive inhibition of 3H-flunitrazepam binding by either flunitrazepam or Ro15-4513 (10(-10)M to 10(-7)M) was performed in the absence and presence of GABA (10(-5)M). In the presence of GABA, the apparent affinity for flunitrazepam was increased approximately 1.7 fold and the apparent affinity for Ro15-4513 was decreased by 1.7 fold. 4. No alteration in the capacity of GABA to modulate flunitrazepam or Ro15-4513 affinity (e.g. GABA-shift) was observed in cortical membrane preparations either 12 or 72 hr following ethanol cessation. 5. Further, no changes in GABA-modulation of flunitrazepam binding was evident 0, 12, 24, or 72 hr after the last ethanol dose in membranes prepared from cortex, hippocampus or cerebellum. 6. Therefore, results from the present study indicate that the capacity of GABA to modulate receptor affinity for benzodiazepine agonists and inverse-agonists in rat cortex, hippocampus or cerebellum is not altered during withdrawal from chronic ethanol.

Animal models of age-related dementia: neurobehavioral dysfunctions in autoimmune mice

The development of strategies for treatment of Alzheimer's disease and other age-associated dementias is an important goal of research in the neurosciences. It is suggested that advances in understanding of the etiology of those disorders would provide the most obvious avenues to development of preventative treatments. Research findings from both clinical investigations and studies of animal models are presented which suggest a neuroimmunologic component in age-associated dementia. Clinical studies suggest an association between dementia and brain-reactive autoantibodies in subsets of patients with Alzheimer's disease. Studies of mice suggest that: 1) when compared with normal genotypes, mutant mice with accelerated autoimmunity show learning and memory impairments at earlier chronological ages; 2) the learning and memory deficits of autoimmune and normal mice are qualitatively similar; 3) the behavioral deficits of normal aged and autoimmune mice are sensitive to similar pharmacologic interventions. Overall, these findings suggest that intervention strategies targeting the immune system might be useful in the treatment or prevention of aging-associated dementia. Autoimmune mice would be useful as models for the development and testing of such immune-based interventions.

Flumazenil improves active avoidance performance in aging NZB/BlNJ and C57BL/6NNia mice

C57BL/6NNia and autoimmune NZB/BlNJ mice aged 12-14 months were tested for acquisition and retention of an active avoidance response following vehicle or flumazenil (40 mg/kg), a benzodiazepine antagonist. Acquisition and retention performance was improved in flumazenil-treated mice when compared with vehicle-treated mice, although the degree of improvement varied with the level of performance in vehicle-treated mice of each strain. The NZB/BlNJ mice, which generally performed more poorly than the C57BL/6NNia mice, showed the greater improvements following flumazenil. These results suggest that antagonism of benzodiazepine receptors leads to improved learning and/or memory performance in mice with spontaneous age-associated deficits.