1 The emetic action of Met-enkephalin, morphine and naloxone was studied following their administration into the cerebral ventricles of dogs through chronically implanted cannulae and the effect on the responses of ablating the chemorceptor trigger zone (CTZ) was investigated. The opiate antagonist, naloxone, was used to determine the role of enkephalin receptors in emetic responses.2 Administration of Met-enkephalin (1.0 mug/kg) into the IVth ventricle regularly evoked emesis with an average latency of 35 s. A dose of morphine (2.5 mug/kg) which was five times larger was required for a consistent emetic response when introduced into the lateral cerebral ventricle (i.c.v.) as compared to the dose required by the IVth ventricular route. The latency of emetic responses by the latter route of injection of morphine was shorter. This is in accord with an action of morphine on the emetic CTZ.3 After bilateral ablation of the CTZ, intraventricular injections of Met-enkephalin and morphine failed to produce emesis even when given in doses that were 5 to 10 times the dose which regularly elicited emesis in animals with intact CTZ. The emesis produced in dogs by intraventricular Met-enkephalin and morphine is thus fully accounted for by an action on the CTZ.4 Naloxone (i.c.v.) in doses up to 10.0 mug/kg did not cause emesis. However, higher doses of naloxone elicited dose-dependent emesis in dogs. The 100% emetic dose of naloxone was found to be 160 mug/kg and the latency of emesis was 180 s. Unlike Met-enkephalin and morphine, naloxone continued to elicit emesis in CTZ-ablated animals.5 Pretreatment with intraventricular naloxone (1 to 8 mug/kg) blocked the emetic responses induced by intraventricular Met-enkephalin and morphine but not that to apomorphine. The selective protective action of the opiate antagonist against Met-enkephalin and morphine supports the presence of enkephalin receptors in the emetic CTZ.

Animals↗

PubMed1981

Gallstone formation : transition of bile constituents into gallstones.

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Adult↗

PubMed1980

Purulent meningococcal arthritis in an adult.

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Arthritis, Infectious↗

PubMed1980

Islets of Langerhans in the parakeet, Psittacula krameri.

The pancreatic gland of Psittacula krameri is divisible into 4 lobes i.e. dorsal, ventral, third and splenic. The endocrine part is composed of alpha 1-, alpha 2- and beta-cells. The islets are of 4 kinds viz., alpha islets (having alpha 1- and alpha 2-cells), beta islets (having beta- and alpha 1-cells), pure beta islets (consisting of beta-cells exclusively) and mixed islets (with beta-, alpha 1- and alpha 2-cells). The distribution of alpha islets is mostly restricted to the splenic and third lobes whereas the beta islets are found in all 4 lobes. Though the alpha islets are only few in the dorsal lobe, their size is best developed in the third and dorsal lobes. Sometimes beta and alpha islets are present in very close proximity but their cells never mingle. An interesting feature was the complete absence of alpha islets from the ventral lobe.A relative abundance of alpha 2- cells in this bird seems to be associated with its comparatively higher blood glucose level and frugivorous habit. Tinctorial reactions suggest that the insulin content of the endocrine pancreas is low. There were no seasonal changes in the islet tissue of P. krameri.

Animals↗

PubMedDate not supplied

Effect of chronic treatment of melatonin on learning, memory and oxidative deficiencies induced by intracerebroventricular streptozotocin in rats.

Intracerebroventricular (ICV) streptozotocin (STZ) has been shown to cause cognitive impairment, which is associated with free radical generation in the brain of rats. Melatonin is a potent free radical scavenger and antioxidant. In the present study, the effect of melatonin was investigated against ICV STZ induced cognitive impairment and oxidative stress in rats. Adult male Wistar rats were injected with ICV STZ (3 mg/kg) bilaterally. The rats were treated with STZ twice, on days 1 and 3. The learning and memory behavior was assessed using passive avoidance paradigms, elevated plus maze and the closed field activity while the parameters of oxidative stress assessed were malondialdehyde (MDA) and glutathione. The rats were treated chronically with melatonin for 21 days starting from day 1 of STZ injection. The learning and memory behavior was evaluated on days 17, 18 and 19 and the rats were sacrificed on day 21 for estimation of MDA and glutathione. The rats treated with melatonin showed significantly less cognitive impairment. There was also insignificant increase in brain MDA and decrease in glutathione levels in melatonin-treated ICV STZ rats as compared to the vehicle-treated ICV STZ animals. The study demonstrates the effectiveness of melatonin in preventing the cognitive deficits as well as the oxidative stress caused by ICV STZ in rats and suggests it's potential in age and age-related neurodegenerative disorders where oxidative stress and cognitive impairment are involved.

Animals↗

PubMedDate not supplied

Protective effect of trans-resveratrol against kainic acid-induced seizures and oxidative stress in rats.

Overexcitation of excitatory amino acid is an important mechanism in seizure genesis wherein free radicals have recently been suggested to play a critical role. Thus, intervention by antioxidants can be a potential beneficial approach in the treatment of epilepsy. The present study was undertaken to see the effect of trans-resveratrol, a potent antioxidant, against kainic acid-induced seizures, and effect on markers of oxidative stress in brain. Kainic acid, 10 mg/kg ip, induced long-lasting seizures and associated symptoms. The brain level of malondialdehyde (MDA) was found to be significantly raised after kainic acid administration (295 +/- 18 nmol/g wet tissue) as compared to control (195 +/- 26 nmol/g wet tissue). Pretreatment (5 min) of single dose of trans-resveratrol (40 mg/kg i.p.) could not inhibit the convulsions though the latency was significantly increased. When multiple doses of trans-resveratrol were injected in two-dose schedules in different animals (20 and 40 mg/kg ip, 5 min prior and repeated 30 and 90 min after kainic acid), there was significant reduction in incidence of convulsions in both treatment schedules. The brain MDA levels were found to be significantly attenuated in the trans-resveratrol-treated groups (multiple doses of 20 and 40 mg/kg) as compared to the kainic acid alone. However, the glutathione level in control, kainic acid- and trans-resveratrol-treated animals were not significantly different. The protective effect of trans-resveratrol against kainic acid-induced convulsions and the attenuation of raised MDA level suggest the potential use of antioxidants at least as adjunct therapy in epilepsy.

Animals↗

PubMedDate not supplied

Effect of Centella asiatica on cognition and oxidative stress in an intracerebroventricular streptozotocin model of Alzheimer's disease in rats.

1. Centella asiatica, an Indian medicinal plant, has been described as possessing central nervous system activity, such as improving intelligence. In addition, we have demonstrated that C. asiatica has cognitive-enhancing and anti-oxidant properties in normal rats. Oxidative stress or an impaired endogenous anti-oxidant mechanism is an important factor that has been implicated in Alzheimer's disease (AD) and cognitive deficits seen in the elderly. 2. Intracerebroventricular (i.c.v.) streptozotocin (STZ) in rats has been likened to sporadic AD in humans and the cognitive impairment is associated with free radical generation in this model. Therefore, in the present study, the effect of an aqueous extract of C. asiatica (100, 200 and 300 mg/kg for 21 days) was evaluated in i.c.v. STZ-induced cognitive impairment and oxidative stress in rats. 3. Male Wistar rats were injected with STZ (3 mg/kg, i.c.v.) bilaterally on the days 1 and 3. Cognitive behaviour was assessed using passive avoidance and elevated plus-maze paradigms on the days 13, 14 and 21. Rats were killed on the day 21 for estimation of oxidative stress parameters (malondialdehyde (MDA), glutathione, superoxide dismutase and catalase) in the whole brain upon completion of the behavioural task. 4. Rats treated with C. asiatica showed a dose-dependent increase in cognitive behaviour in both paradigms. A significant decrease in MDA and an increase in glutathione and catalase levels were observed only in rats treated with 200 and 300 mg/kg C. asiatica. 5. The present findings indicate that an aqueous extract of C. asiatica is effective in preventing the cognitive deficits, as well as the oxidative stress, caused by i.c.v. STZ in rats.

Alzheimer Disease↗

PubMedDate not supplied

Ocular drug targeting by liposomes and their corneal interactions.

Topical drug delivery is preferred in the eye to avoid under or over medication and undesired side effects of systemic administration. In order to maintain adequate drug levels in ocular tissues, frequent drug installation is necessary in vision threatening conditions like glaucoma, corneal ulcers due to microbial infections, etc. Only a part of the installed drug reaches the aqueous humor and the rest of it is drained by the nasolacrimal duct. Positively charged liposomes have been found to enhance the penetration of drugs into the cornea. The present study was conducted to visualize the interaction of liposomes with the cornea. Briefly, positively charged liposomes entrapped with Carboxyfluorescein (CF), Propidium iodide (PI), Horseradish peroxidase (HRP), Biotin, Hydroxy benzimide (Hoechst No: 33258), and Ethoxy benzimide (Hoechst No: 33342) were prepared by sonication. Their size and shape were analysed by laser dynamic light spectra and electron microscopy, respectively. The liposome encapsulated and free materials in buffer were instilled, in a volume of 20 microliters, into eyes of anesthetized albino rats. After 30 min and 1 h, the eyes were enucleated and quickly processed for cryosections of 3-5 microns thickness. The interaction of liposome entrapped propidium iodide and HRP was visualized on the outer epithelium of the cornea after specific processing.

Animals↗

PubMedDate not supplied

Effect of different lithium priming schedule on pilocarpine-induced status epilepticus in rats.

The conventional method of inducing status epilepticus by injecting pilocarpine 24 h after lithium chloride (LiCl) administration lacks kinetic correlate. Therefore, the present study was conducted to see the effect of altering the time schedule of lithium administration (from 2 to 72 h) on the convulsive behavior in response to pilocarpine challenge in rats. It was observed that reducing the pretreatment time of lithium from 24 to 2 h produced convulsions in 100% of the rats. However, incidence of convulsions decreased when lithium pretreatment time was increased to 48 h and no convulsions were recorded with 72-h lithium time schedule. The neuronal damage assessed histologically and the effectiveness of diazepam was similar irrespective of time schedule. This study provides evidence that LiCl pretreatment schedule can be adopted at any time between 2 to 24 h to suit the convenience and objectives of the experiment.

Animals↗

PubMedDate not supplied

Adenosinergic and dopaminergic interaction in nigrostriatum in FeCl3-induced model of parkinsonism in rats.

The effect of adenosine modulating drugs was studied in the FeCl3-induced model of parkinsonism in rats. In rats bearing unilateral FeCl3 induced lesion of the dopaminergic nigrostriatal pathway, stimulation of adenosine receptors with adenosine, dose-dependently reduced the ipsilateral rotations induced by apomorphine. A specific agonist of adenosine A2A receptor, CGS-21680, also completely blocked the rotations while the specific A2 receptor antagonist, CGS-15943A, potentiated rotations induced by apomorphine. The nonspecific adenosine antagonist, theophylline (50 mg/kg i.p.) potentiated stereotype behavior although blocking rotations. This study provides evidence for a negative postsynaptic interaction between dopamine and adenosine receptors.

Adenosine↗

PubMedDate not supplied

Dopaminergic involvement in adenosine A1 receptor-mediated antinociception in the tail flick latency model in mice.

The interaction between the adenosinergic and dopaminergic systems in nociception was assessed in the tail flick latency (TFL) test in mice. Adenosine exhibited qualitatively different responses depending on the dose: Adenosine 10 and 100 mg/kg i.p. caused antinociception as evidenced by an increase in TFL while the middle dose of 30 mg/kg decreased TFL. On the other hand, the specific adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) at doses of 0.05, 0.1, 0.25 and 0.5 mg/kg (i.p.) resulted in dose-dependent antinociception. The antinociceptive effect of CPA was reversed by classical albeit nonspecific adenosine receptor antagonist theophylline (5 mg/kg) at a dose which had no effect on TFL per se. A low dose (1 mg/kg i.p.) of the dopaminergic agonist apomorphine caused an early mild hyperalgesic response while the high dose (10 mg/kg i.p.) had no significant effect on TFL. The antinociceptive effect of CPA was attenuated by pretreatment with low dose apomorphine while pretreatment with the high dose caused mild but insignificant potentiation. Theophylline, when administered prior to apomorphine failed to modify the nociceptive response. The results suggest that an interaction between adenosine and dopamine may be involved in nociception.

Adenosine↗

PubMedDate not supplied

Juxtacortical osteogenic sarcoma of mandible. A case report.

Juxtacortical osteogenic sarcoma of bone is a relatively uncommon form of osteogenic sarcoma. In the jaw bones, it is extremely rare. Here, we present a case of Juxtacortical Osteogenic Sarcoma of mandible in a 45 year old man which presented as an epulis in the mandibular incisor region.

Diagnosis, Differential↗