The possible modulation of morphine analgesia by the supramolecular GABA receptor complex.

In the present study, the mechanism of the antagonistic action of 0.5 mg/kg diazepam on the analgesic effect of morphine was investigated. While Ro 15-1788, a benzodiazepine receptor antagonist, was found to partially reverse the inhibitory action of diazepam on morphine analgesia, a chloride channel blocking agent, picrotoxin, produced complete antagonism of the action of diazepam. Furthermore, picrotoxin potentiated the partial antagonistic effect of Ro 15-1788 at a normally ineffective dose to affect the 0.5 mg/kg diazepam-morphine dose-response curve. These overall effects of picrotoxin on the supramolecular GABA receptor complex are discussed.

Melperone treatment in an organic delusional syndrome induced by hyperprolactinemia: a case report.

A young female with organic delusional syndrome induced by hyperprolactinemia was admitted to the Psychiatry Clinic of Ankara Social Security Hospital. The most striking characteristic of her history was either worsening of the endocrinologic clinical outcome under conventional neuroleptic treatment or worsening of clinical psychiatric outcome under bromocriptine therapy. A new atypical neuroleptic, melperone, suggested to minimally affect plasma prolactin levels, was started. Her psychotic complaints significantly subsided and she was devoid of any symptomatological change regarding her endocrinological status. These results were discussed.

The effects of flumazenil on two way active avoidance and locomotor activity in diazepam-treated rats.

The present study was undertaken to determine the effects of chronic flumazenil treatment alone and simultaneously with diazepam on acquisition performance in an active-avoidance task and on locomotor activity in rats. Flumazenil (5, 10 and 20 mg/kg) and diazepam (0,5, 1.0 and 2.0 mg/kg) were administered intraperitoneally to rats before each daily training session for 5 days. The baseline of avoidance performance was set to approximately 50% and responses were expressed as acquisition rate. Locomotor activity of the rats was simultaneously recorded but only following the first training session. Diazepam decreased acquisition rate between the dose range used. Flumazenil had no effect on the acquisition rate of naive rats but reversed low dose diazepam-induced learning and memory impairment. Diazepam induced locomotor depression within the same dose range that decreased acquisition rate. Flumazenil had no effect on locomotor activity, but reversed the locomotor depressant effect of diazepam. The striking contradiction with previous data that flumazenil has no effect on learning-memory processing is discussed.

Antiseizure activity of insulin: insulin inhibits pentylenetetrazole, penicillin and kainic acid-induced seizures in rats.

The present study was undertaken to evaluate the antiseizure activity spectrum of insulin against various behavioral seizure models in rats. Insulin was injected intraperitoneally (i.p.) at a test dose of 1 U/kg. Dextrose (3 g/kg) was administered simultaneously with insulin to counteract its hypoglycemic effect and induce a normoglycemic state. Insulin was found to significantly decrease the incidence, intensity and mortality rate and prolong the latency of generalized tonic-clonic convulsions induced by pentylenetetrazole (60 mg/kg i.p.) and significantly decrease the intensity and mortality rate and prolong the latency of generalized tonic-clonic convulsions induced by penicillin (2000 U/intracerebrocortical). Insulin was not only found to prolong the latency of all the seizure components but was found to reduce the incidence of focal myoclonic twitches and generalized tonic-clonic convulsions induced by kainic acid (12 mg/kg i.p.) as well. Insulin was shown to be ineffective to suppress ouabain (5 micrograms/intracerebroventricular) induced seizures. These findings indicate that insulin possesses a broad spectrum of antiseizure activity in rats. Interaction with brain Na(+)-K(+)-ATPase has been discussed as a possible mechanism of action.

The possible role of benzodiazepine receptors in morphine analgesia.

Diazepam within its therapeutic dose range, was shown to have no effect on nociception, but was shown to antagonize the analgesic action of morphine. This antagonism was found to be statistically significant at 0.5 mg/kg diazepam. To elucidate the mechanism of this inhibitory action of diazepam against morphine analgesia, Ro 15-1788, the specific antagonist of benzodiazepine receptors was used. As a result, Ro 15-1788 was found to partially reverse the inhibitory action of diazepam against morphine analgesia. This overall interaction between the supramolecular GABA receptor complex and morphine is discussed.

The art of scientific presentation.

While scientific research data can only become widespread by scientific communication, scientists generally underestimate the importance of communicating effectively. The present article is a current informational review of the guidelines for effective oral and poster presentation for young scientists. Emphasis has been given not only to effective structuring of the content but to effective verbal and non-verbal presentation techniques as well. References are mostly Internet sources, thus, have not been cited throughout the article but given at the end as a whole.

Iloprost-induced writhing in mice and its suppression by morphine.

Intraperitoneally (i.p.) administered iloprost produced a writhing response indicating nociception. This effect induced by 4 micrograms/kg iloprost was dose dependently protected by morphine with an ED50 (95% confidence limits) value of 0.039 (0.0018-0.067) mg/kg. On the other hand, indomethacin had no effect on iloprost-induced writhing. Thus, this effect of iloprost seems to be relatively more sensitive than other irritants-induced responses on determining the analgesic potency of narcotic drugs.

Perceptions of students in different phases of medical education of educational environment: ankara university faculty of medicine.

The present study was undertaken to identify the perceptions of students about their educational environment in a newly restructured curriculum. The Turkish version of the DREEM questionnaire (total score: 200) was used to diagnose the strengths and weaknesses of the curriculum which is known to be a major determinant of educational environment. Five hundred fifty three students (years 1, 3, 5) voluntarily replied to the questionnaire. The mean DREEM score was found to be 117.63 (58.8%). The mean scores for the whole DREEM questionnaire and the five essential domains were found to be significantly different in different phases of medical education. The scores were found to be highest (123.65) for year 3 students and lowest (109.39) for year 5 students. The results are the first data of a curriculum reform obtained from the students about the educational environment and give important feedback to curriculum planners and change managers of the faculty for necessary improvement.

Dynamic properties of a retrograde superfusion system for isolated right atria including effects of histamine H2 receptor agonists.

A retrograde superfusion technique is described for spontaneously beating guinea pig right atrium where both force of contraction and rate are recorded simultaneously. Drugs are applied to the system in bolus injections and the concentrations attained in the organ bath after these injections are computed through an analog system by means of measuring injected dye dilutions in a spectrophotometer. Actions of histamine and histamine H2-receptor agonists 4-methyl histamine, dimaprit, and impromidine on the preparation for the mentioned parameters are investigated. By comparing responses to bolus injections with infusions of agonists, it is concluded that all four agonists tested are rapidly passing to the biophase, and the system can be used as an alternative for the classical organ bath. Dose-response characteristics of the tested agonists are satisfactory and affinity values found are in agreement with the values reported for bathed systems.

Segmental and age-dependent changes of histamine's affinity in the rabbit aorta.

Affinities of contractile responses to histamine and H1-receptor agonists thiazolylethylamine (TEA) and pyridylethylamine (PEA) were evaluated in three segments of rabbit aorta and increase of affinity in the caudal direction was found. alpha-adrenergic affinity of noradrenaline did not possess such differentiation. Evaluation of the data with histamine receptor agonists and antagonists suggested H1-receptor liability of the phenomena. Affinities of histamine and noradrenaline were also investigated in relation to body weight which reflects age. Histamine's affinity was found to be age dependent, decreasing with the increase of age, while no correlation was found for noradrenaline between two parameters. Results are suggesting the presence of histamine specific vascular function in the rabbit which is receded by the advance of age.

Histamine H2 receptor subtypes in the guinea pig right atrium.

Inotropic and chronotropic responses to histamine and to selective histamine H2 receptor agonists (4-methyl histamine, dimaprit, impromidine) and antagonists (metiamide and cimetidine) were studied in retrogradely superfused guinea pig right atrium preparations. All agonists tested were acting as chronotropic and, except impromidine, as inotropic agonists; impromidine had a dual inotropic action. Affinities of the antagonists varied, showing approximately 20-fold more activity on chronotropism. The findings suggest the existence of subtypes of histamine H2 receptors in the development of chronotropic and inotropic responses.

Behavioural assessment of pinealectomy and foetal pineal gland transplantation in rats: Part II.

Pineal gland is an endocrine organ which exerts regulatory effects on the activity of various organs and systems. The present study was undertaken to highlight in experimental animals the possible integrative function of this endocrine organ on a behavioural pattern. Pinealectomy and foetal pineal gland transplantation to a subpial cortical area close to the pinealectomized region was performed. Behaviour was defined through motor activity induced by low (2 mg/kg) and high (10 mg/kg) doses of amphetamine in rats. It was shown that pinealectomy produced significant different patterns of behaviour induced by low and high doses of amphetamine. In sham operated animals low dose amphetamine induced a significant locomotor stimulation but without stereotyped activity. High dose amphetamine induced stereotyped activity. After pinealectomy even low dose amphetamine produced the behavioural pattern of stereotyped activity resembling a high dose amphetamine-induced behaviour. This differential effect of amphetamine, seen in pinealectomized rats, was completely restored after transplantation. On the other hand, melatonin treatment did not generate a significant alteration of behavioural profile either in the control or pinealectomized group of rats. Results are discussed with regard to the general regulatory function of the pineal gland.

Melatonin as a free radical scavenger in experimental head trauma.

Head trauma causes two kinds of injury in the neural tissue. One is the primary injury which occurs at the time of impact. The other one is a secondary injury and is a progressive process. Free radicals are produced during oxidative reactions formed after trauma. They have been thought to be responsible in the mechanism of the secondary injury. Some studies have been conducted to demonstrate the role of free oxygen radicals in neuronal injury. The alterations in the free radical level during the early posttraumatic period and the effect of a free radical scavenger on these alterations have not been studied as a whole. We aimed to demonstrate the free oxygen radical level changes in the early posttraumatic period and the effect of melatonin, which is a potent free radical scavenger, on the early posttraumatic free radical level. A two-staged experimental head trauma study was designed. In stage one, posttraumatic free radical level changes were determined. In the second stage, the effect of melatonin on the free radical level changes in the posttraumatic period was studied. Two main groups of rats each divided into four subgroups were studied. Rats in one of the main groups underwent severe head trauma, and malondealdehyde (MDA) levels were measured in the contused cerebral tissue at different time points. Rats in the other main group also underwent the same type of trauma, and melatonin was injected intraperitoneally at different time points after trauma. The MDA level alteration in the tissue was determined after the injection of melatonin. The MDA level increased rapidly in the early posttraumatic period. But in time, it decreased in the groups with only trauma. In the melatonin-treated group, the MDA level decreased after the injection of melatonin, when injected in the early posttraumatic period, compared to the control and trauma groups. However, melatonin increased MDA to a higher level than in the groups with only trauma and the control group when injected later than 2 h after trauma. The MDA level increases in the very early posttraumatic period of cerebral trauma and decreases in time. Melatonin, which is the most potent endogenous free radical scavenger, when injected intraperitoneally to the cerebral traumatized rats in the very early posttraumatic period, causes a significant decrease in the MDA level. But, melatonin, when injected more than 2 h after trauma, increases the MDA level in experimental cerebral trauma in rats.