Neurochemical and behavioral effects of fluoxetine on midazolam induce dependence in an animal model of addiction

In the present study we have monitored effects of repeated coadministration of fluoxetine with midazolam; a benzodiazepine (CNS depressant). It is the primary drug of choice for procedural sedation, preoperative sedation, and in emergency departments. Repeated administration of this drug is reported to have abuse potential and may cause this by increasing dopaminergic neurotransmission. Since an important role of serotonin is there in the pathophysiology of anxiety and addiction, administration of midazolam may involve altered 5-HT metabolism as well. Present study was designed to monitor effects of repeated administration of fluoxetine with midazolam. Effects of fluoxetine and midazolam coadministration were monitored on motor activities in familiar and novel environments, hot plate test, forced swim test, conditioned place preference test and levels of dopamine, 5-HT and their metabolites. Both midazolam (2.5mg/kg) and fluoxetine (1mg/kg) were administered orally for 12 days. Conditioned place preference test was performed on day 13. Rats were decapitated and whole brain samples were collected and stored at -70°C until neurochemical analysis by HPLC-EC. Findings from the present study show attenuation of midazolam-induced reinforcement upon repeated co-administration of fluoxetine. These could be implicated to increased therapeutic utility of midazolam and related benzodiazepines.

Neurochemical and behavioral effects of lorazepam: A dose related study

Present study was designed to monitor the dose dependent effects of lorazepam; a benzodiazepine (CNS depressant). It is the primary drug of choice for treatment of anxiety and to produce calming effects. However, repeated administration of this lorazepam causes dependence and this might be caused by increased dopaminergic neurotransmission. Besides dopamine, 5-hydroxy tryptamine (5-HT) has also been reported to have pivotal role in the pathophysiology as well as treatment of anxiety and addiction. Repeated administration of lorazepam might involve altered 5-HT metabolism as well. Present study was therefore designed to monitor dose-dependent effects of lorazepam and to select its optimum dose for further experiments and pharmacological interventions. Effects of lorazepam were monitored on food intake, growth rate, activities in familiar and novel environments, light dark box activity, forced swim test and metabolism of dopamine and 5-HT. oral administration of lorazepam was done at the doses of 0mg/kg, 2mg/kg, 4mg/kg and 6mg/kg. Behaviors parameters were monitored following single administration of lorazepam. Rats were decapitated and whole brain samples were collected and stored at -70°C until neurochemical analysis by HPLC-EC. Findings from the present study could be implicated to increased therapeutic utility of lorazepam and related benzodiazepines.

Effects of single administration of apomorphine on memory and monoamine metabolism: A dose related study

In the present study, we have monitored dose dependent effects of apomorphine on learning and memory. Behavioral sensitization and craving, which develop upon repeated treatment with dopamine receptor agonist apomorphine, are major limitations of the therapeutic use of apomorphine in Parkinson's patients. Effects of single (intraperitoneal) injection of apomorphine at different doses (i.e., 0.5, 1.0, & 2.0 mg/ml/kg) on locomotion in a familiar environment (Skinner's box) and memory in Morris water maze were investigated. Results show significantly enhanced activity in Skinner's box in a dose dependant manner. Low dose (0.5 mg/ml/kg) of apomorphine impaired both short- as well as long-term memory while both high and moderate doses of the drug (1.0, & 2.0 mg/ml/kg) enhanced the cognitive profile in rats. However, the memory-enhancing effects of apomorphine at moderate (1.0 mg/ml/kg) dose were more pronounced as compared to high (2.0 mg/ml/kg) dose of the drug. Rats were decapitated on day 2. Whole brains of rats were collected and stored at -70°C. Biogenic amines (i.e., 5-Hydroxytryptamine; 5-HT and dopamine) and metabolites (i.e., Dihydroxyphenylacetic acid; DOPAC, Homovanillic acid; HVA & 5-Hydroxyindoleacetic acid; 5HIAA) were estimated by reverse phase High Performance Liquid Chromatography with electrochemical detector (HPLC-EC). Both low (0.5mg/ml/kg) as well as moderate (1.0mg/ml/kg) dose of apomorphine increased levels of dopamine, DOPAC, HVA, 5-HT and 5-HIAA. Whereas, high (4.0 mg/kg) dose of apomorphine increased levels of dopamine, DOPAC and HVA, while decreased 5-HT and 5-HIAA levels. Results would be helpful in elucidating memory enhancing effects of apomorphine at different doses and its implication for extending therapeutics in cognitive disorders.

Characteristics, socioeconomic status and ethnic variations of primary idiopathic macular hole repair in vitreoretinal centers in the United Kingdom

OBJECTIVE

The purpose of this multicentre retrospective study was to investigate the characteristics and role of ethnicity and socioeconomic status amongst patients with idiopathic macular holes (IMH) and the surgical outcome.

SUBJECTS AND METHOD

Consecutive patients undergoing primary IMH surgery at three vitreoretinal units in the UK (King's College Hospital, London, UK, Western Eye Hospital, London, UK, Sunderland Eye Infirmary, Sunderland, UK) between January 2007 and May 2017 were included. The main outcome measure was anatomical closure of IMH.

RESULTS

Two hundred and thirty three primary IMH surgeries were included. All patients underwent pars plana vitrectomy, internal limiting membrane peeling, and gas tamponade. 69.10% of patients were European Caucasian, 6.44% were Asian, and 24.46% were Afro-Caribbean. The mean base macular hole diameter (BD) was 475.5mcm. Mean BD was 432.2mcm in European Caucasian patients, 481.3mcm in Asians (P=0.005), and 505.61mcm in Afro-Caribbeans (P=0.006). Regression analysis demonstrated that BD and Afro-Caribbean ethnicity were independent significant risk factors for surgical failure. Those who have longer duration of symptoms (Afro-Caribbeans) and leave in more deprived places (Afro-Caribbeans) in England where found to have lower success rate on macular hole closure.

CONCLUSION

Asian and Afro-Caribbean patients present with larger IMH than European Caucasians. In addition to IMH base diameter, black origin and lower socioeconomic status are independent risk factors for surgical failure. This study presents a large population-based data analysis on ethnic variation in macular holes and may assist in the management and predicting the surgical outcome.

Grading nuclear cataract: reproducibility and validity of a new method

AIMS

To assess the reproducibility and validity of a new instrument for grading nuclear cataract-the laser slit lamp, by comparison with an established method of lens grading-the Lens Opacities Classification System III (LOCS III).

METHODS

62 volunteers (113 eyes) were examined on two occasions. At each visit, a video image of the anterior segment was captured with the laser slit lamp and stored digitally. A measure of lens opacity for each laser slit lamp image was calculated using image analysis software. Each lens was also photographed on both visits for LOCS III grading of nuclear colour and nuclear opalescence.

RESULTS

There was a linear increasing relation between the laser slit lamp measure of nuclear lens opacity and the LOCS III nuclear opalescence scores. The overall reproducibility of the laser slit lamp measurement was comparable with LOCS III (intraclass correlation coefficient of 95% (95% CI 92.9-96.5) for the laser slit lamp method; 97% (95% CI 95. 6-97.9) for the LOCS III method). However, among healthy subjects, the reproducibility was lower (intraclass correlation for the laser slit lamp of 38.6% (95% CI 12.9-59.2) and 76.1% (95% CI 62.3-85.4) for LOCS III.

CONCLUSION

The laser slit lamp appears to give a valid measurement of nuclear cataract. The reproducibility of the instrument was high and similar to that of LOCS III. Modifications to the design would have to be made to improve its reproducibility among healthy subjects. It is simpler than other objective instruments, and could be useful in large scale studies of cataract.