5-HT1A receptors are differentially involved in the anxiolytic- and antidepressant-like effects of 8-OH-DPAT and fluoxetine in the rat.

Fluoxetine, a selective serotonin reuptake inhibitor, shows moderate efficacy and potency in the rat forced swimming depression test and the shock-induced ultrasonic vocalization anxiety test, whereas the 5-HT(1A) receptor agonist (+/-)-8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) is highly efficient and potent in both models. Whereas the 5-HT(1A) receptor antagonist WAY 100,635 abolishes the effect of 8-OH-DPAT in both models, it only attenuates the antidepressant-like effect of fluoxetine. Pretreatment with the 5-HT-depleting agent parachlorophenylalanine attenuates the antidepressant-like effect of fluoxetine, but not that of 8-OH-DPAT. This suggests that the antidepressant-like effect of fluoxetine and 8-OH-DPAT results from indirect (via increased synaptic availability of 5-HT) and direct stimulation of postsynaptic 5-HT(1A) receptors, respectively; whereas the anxiolytic-like effect of fluoxetine is not mediated by 5-HT(1A) receptors. The data support the hypothesis that the antidepressant- and anxiolytic-like effect of 8-OH-DPAT is predominantly mediated by post- and presynaptic 5-HT(1A) receptors, respectively, and that 5-HT(1A) receptors are only partially involved in the antidepressant-like effect of fluoxetine.

Behavioral effects of cannabinoids show differential sensitivity to cannabinoid receptor blockade and tolerance development.

This study compared the potency and efficacy of the cannabinoids delta-tetrahydrocannabinol (delta-THC), HU-210, WIN 55,212-2 and CP 55,940 in suppressing food-reinforced operant behavior, increasing reaction latency in a hot-plate test and inducing hypothermia, and tested whether these behavioral effects induced by CP 55,940 showed differential sensitivity to the cannabinoid CB1 receptor antagonist SR141716A, and to tolerance development. After acute i.p. administration to rats, operant behavior was more potently affected than reaction latency and body temperature, but the order of potency of the different drugs was similar across the tests: HU-210

Partial agonist-like profile of the cannabinoid receptor antagonist SR141716A in a food-reinforced operant paradigm.

Both cannabinoid CB1 receptor agonists, such as delta-tetrahydrocannabinol (delta-THC), CP 55,940 and WIN 55,212-2, and the antagonist/inverse agonist SR141716A, dose-dependently suppress operant behavior. The present study investigated to what extent combined i.p. application of SR141716A with these cannabinoids resulted in mutually antagonistic effects, in additive effects, or in no interactive effects on operant responding in rats trained in a fixed-ratio 10, food-reinforced 10-min procedure. Pretreatment with SR141716A either had no effect on (at 0.3-1mg/kg), or partially blocked (at 3 mg/kg), the inhibitory effects on responding induced by delta-THC (3-5 mg/kg) and CP 55,940 (0.03-0.2 mg/kg). Interestingly, while 3 mg/kg SR141716A induced moderate inhibitory effects on operant responding, its combination with either agonist resulted in the same level of inhibitory activity on responding as that obtained by SR141716A when tested alone. Pretreatment with a low dose of CP 55,940 (0.01 mg/kg) or WIN 55,212-2 (0.3 mg/kg) did not affect response inhibition induced by SR141716A. Combination of SR141716A (0.5 and 1mg/kg) with delta-THC (3 mg/kg) resulted in the same level of response inhibition, independently of whether SR141716A was given 5 min before or 15 min after delta-THC. Although alternative explanations are conceivable, the data may indicate that SR141716A is a partial agonist at those cannabinoid receptors mediating the response-rate suppressive effects of cannabinoids.

Intrinsic activity estimation of cannabinoid CB1 receptor ligands in a drug discrimination paradigm.

The present study estimated the apparent intrinsic activity of the cannabinoid CB1 receptor ligands CP 55,940, Delta9-tetrahydrocannabinol (Delta9-THC) and SR 141716A in a highly sensitive in vivo assay. Rats were trained to discriminate the cannabinoid CB1 receptor agonist CP 55,940 (either 0.03 or 0.014 mg/kg, i.p., t=30 min) from vehicle, in a two-lever food-reinforced procedure, and were subsequently tested with the three compounds. Although reduction of the training dose did not affect the maximum level of generalization or antagonism (>80% generalization for CP 55,940 and Delta9-THC; 0% generalization and >80% antagonism for SR 141716A), the potency of the compounds was differentially affected. Thus, the generalization curves obtained with CP 55,940 and Delta9-THC were shifted three- and sixfold to the left; whereas no potency difference was obtained for the antagonism of CP 55,940 by SR 141716A. The data are consistent with the hypothesis that the level of intrinsic activity of CP 55,940 is higher than that of Delta9-THC, and that SR 141716A may have a very low level of intrinsic activity. It is concluded that variation of the training dose increases the sensitivity of the in vivo intrinsic activity estimation of cannabinoid CB1 receptor ligands.

Effects of serotonin 5-HT(1/2) receptor agonists in a limited-access operant food intake paradigm in the rat.

Hypophagic effects of serotonergic drugs have mostly been investigated in free-feeding paradigms and are generally ascribed to drug-induced acceleration of satiety, or to behavioral disruption. The present study investigated the hypophagic effects of various 5-HT(1/2) receptor agonists in an operant paradigm. Because of its limited duration (10-min session) the procedure was considered to be relatively insensitive to satiety processes. The behavioral specificity of the hypophagic effect was assessed by additional testing of the compounds in a locomotor activity assay. Male Wistar rats, maintained at about 80% of their free-feeding weights, were trained to acquire stable operant responding in daily fixed ratio:10 food-reinforced sessions; after which they were tested once a week with a 5-HT receptor agonist. Each compound dose-dependently suppressed the number of earned pellets after i.p. administration: DOI (5-HT(2A/2C) receptor agonist; ED(50): 0.36 mg/kg), TFMPP (5-HT(1B/2C/2A); 0.37 mg/kg), m-CPP (5-HT(2C/1B/2A); 0.54 mg/kg), ORG 37684 (5-HT(2C/2A); 0.85 mg/kg), CP-94,253 (5-HT(1B); 2.09 mg/kg), BW 723C86 (5-HT(2B); 6.26 mg/kg) and ipsapirone (5-HT(1A); 10.17 mg/kg). When tested at the dose equivalent to the ED(50) value in the operant paradigm, only ORG 37684 and DOI weakly suppressed activity counts in a locomotor activity assay; suggesting that the inhibition of operant food intake obtained with the other compounds at these doses is not a direct consequence of unconditioned motor effects. It is suggested that the hypophagic effect induced by relatively low doses of CP-94,253, TFMPP and m-CPP, and by moderate doses of ipsapirone and BW 723C86, is partly due to a drug-induced suppression of appetite. Although the exact contribution of the diverse 5-HT(1/2) receptor subtypes to appetite control remains to be studied in more detail, it is hypothesized that activation of 5-HT(1B) and/or 5-HT(2C) receptors attenuates appetite.

Role of the NMDA receptor NR2B subunit in the discriminative stimulus effects of ketamine.

The noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, ketamine, is a dissociative anesthetic with antihyperalgesic properties. However, its clinical use is compromised by psychotomimetic side-effects. As ketamine and other noncompetitive NMDA antagonists, such as phencyclidine and dizocilpine, are not selective for the NR2A-2D subunits of the NMDA receptor, it is unclear which of these subunits is responsible for the psychotomimetic side-effects. This study investigated the role of the NR2B subunit in the ketamine drug discrimination model, a possible correlate for such side-effects. In a first experiment aimed at assessing general potency and time dependency, ketamine, dizocilpine, phencyclidine and the NR2B-selective antagonists ifenprodil and Ro 25-6981, dose-dependently suppressed fixed ratio 10 food-reinforced responding in rats, with peak efficacy obtained around 15-40 min. In rats trained to discriminate ketamine from vehicle in a two-lever fixed ratio 10 food-reinforced procedure, ketamine, dizocilpine, phencyclidine and Ro 25-6981 induced complete generalization (>80%); whereas ifenprodil induced partial generalization (33%). These findings suggest that the NR2B subunit is involved in the discriminative stimulus effects of noncompetitive NMDA antagonists, and that selective NR2B antagonists may also induce psychotomimetic side-effects.

Acute stress induced modifications of calcium signaling in learned helpless rats.

Previous reports have demonstrated reduced elevations of free intracellular calcium concentration in blood cells of depressed patients after various stimuli. Therefore, a disturbance of intracellular calcium (Ca2+) homeostasis has been postulated to be involved in the pathophysiology of mood disorders. It was the aim of the present study to investigate whether Ca2+ signaling was affected in spleen T-lymphocytes of rats submitted to a learned helplessness paradigm, an animal model of depression with a high level of construct, face and predictive validity. In addition, we tested for effects of acute stress on the Ca2+ signaling in helpless rats, as compared to non-stressed rats. It was found that mitogen-induced Ca2+ signaling only tended to be reduced in helpless rats. However, when helpless rats were submitted to acute immobilization stress, Ca2+ signaling appeared to be significantly blunted, whereas the same stressor did not affect Ca2+ signaling in the non-helpless control rats. These acute stress-induced differences in Ca2+ signaling were not paralleled by a differential increase in plasma corticosterone. It is hypothesized that blunted Ca2+ signaling, as assessed in spleen T-lymphocytes of helpless rats, may be a correlate of the increased vulnerability of helpless rats to acute stressors.

Comparison of hypericum extracts with imipramine and fluoxetine in animal models of depression and alcoholism.

Clinical evidence suggests that hypericum extracts (Hypericum perforatum L., St. John's wort) have antidepressive properties and may offer an interesting alternative for the treatment of mood disorders. In addition, hypericum extracts, as well as standard antidepressants such as the tricyclic, impramine, and the selective serotonin reuptake inhibitor, fluoxetine, have been reported to be of therapeutic benefit in the treatment of alcoholism, as these compounds may reduce alcohol craving and/or intake in particular subgroups of patients. It was the aim of the present study to compare the effects of hypericum extracts with those of imipramine and fluoxetine in the rat forced swimming test (RFST), a model of depression, as well as in cAA rats, a genetic model of alcoholism. In the RFST, triple i.p. administration of imipramine (3-30 mg/kg) and fluoxetine (3-30 mg/kg) induced a dose-dependent reduction in immobility: the minimal effective dose (MED) being 30 and 10 mg/kg, and the maximal effect being 50% and 57% immobility reduction, for imipramine and fluoxetine, respectively. In this test, the hypericum extracts Ze 117 (Remotiv) and LI 160 (Jarsin) also induced a statistically significant reduction of immobility when administered under the same application schedule (5-40 mg/kg, i.p., triple application). In the case of the hypericum extracts the dose-response relationship was inverted U-shaped with a MED value of 20 mg/kg and a maximal effect of 41% and 32% immobility reduction, for Ze 117 and LI 160, respectively. Interestingly, the anti-immobility effects tended to be more pronounced after subacute (1 week, B.I.D.) treatment with 10 mg/kg of imipramine, fluoxetine, or Ze 117, as compared with acute treatment. This phenomenon is in accordance with clinical experience and suggests that repeated treatment is required for full development of antidepressive effects. In the alcohol-preferring cAA rats, acute i.p. administration of imipramine (3-30 mg/kg), fluoxetine (1-10 mg/kg) and Ze 117 (10-40 mg/kg) dose-dependently reduced alcohol intake in a 12-h limited access two-bottle [ethanol 10% (v/v) versus water] choice procedure: with MED values of 30, 5 and 20 mg/kg, respectively. The anti-alcohol effects of fluoxetine and Ze 1-17 appeared to be specific, as reductions in alcohol intake coincided with reductions in alcohol preference. The present study suggests that hypericum extracts have antidepressant-like properties which resemble those of clinically established antidepressants, and that Remotiv may be an interesting adjunct for the treatment of alcoholism.

Discriminative stimulus properties of the 5-HT1A receptor agonist BAY x 3702 in the rat.

The aminomethylchroman derivative BAY x 3702 (R-(-)-2-¿4-[(chroman-2-ylmethyl)-amino]-butyl¿-1,1-dioxo-benzo[d] isothiazolone HCl) has recently been characterized as a relatively selective, high affinity 5-HT1A receptor agonist with neuroprotective, anxiolytic- and antidepressant-like effects in animal models. It was the aim of the present study to further confirm its receptor binding profile in an in vivo assay. Rats were trained to discriminate BAY x 3702 (0.1 mg/kg, i.p.) from vehicle in a standard two-lever fixed ratio 10 food-reinforced procedure. All rats learned the discrimination, the median number of sessions to reach criterion being 38 (range: 22-58 sessions). Generalization tests with BAY x 3702 showed dose-dependent and complete generalization after different routes of administration; the ED50 values being: 0.030, 0.007 and 0.36 mg/kg, after i.p., i.v. and p.o. administration, respectively. Assessment of the duration of action after administration of 0.1 mg/kg BAY x 3702, i.p., resulted in a T1/2 of 65 min. Dose-dependent and complete generalization was also obtained with the 5-HT1A receptor agonists 8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)-tetralin, ED50 in mg/kg, i.p.: 0.086), flesinoxan (0.30), SR 57746A ((4-(3-trifluoromethylphenyl)-N-(2-(naphth-2-yl)ethyl)-1,2,3,6-tet rahydropyridine HCl, 1.0), the (+)-enantiomer of BAY x 3702 (1.3) and ipsapirone (1.8); the ED50 values being closely correlated with their respective affinities for the 5-HT1A receptor. Pretreatment with the selective 5-HT1A receptor antagonist WAY-100635 ((N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N(2-pyridinyl) cyclohexane carboxamide trihydrochloride) dose-dependently and completely blocked the discriminative effects of 0.1 mg/kg BAY x 3702 (ID50: 0.013 mg/kg, i.p.). WAY-100635, prazosin, idazoxan, raclopride, paroxetine, (-)-BAY k 8644 (methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoro-methyl-phenyl)-p yridine-5-carboxylate), ethanol, and the putative neuroprotectants MK-801 ((+)-5-methyl-10,11-dihydroxy-5H-dibenzo(a,d)cyclohepten-5,10-imin e), CNS 1102 (N-(1-naphthyl)-N'-(3-ethylphenyl)-N'-methyl-guanidine), CGS 19755 (cis-4-(phosphonomethyl) piperidine-2-carboxylic acid) and nimodipine did not induce more than 20% generalization. It is concluded that the BAY x 3702 cue is mediated by its agonistic activity at 5-HT1A receptors.

A rapid phantom technique for checking blocked vertex fields.

A simple phantom technique for quality assurance in beam arrangements involving a vertex field is described. Clinical personnel can quickly check that blocks for the vertex field have been cut to the proper magnification and that the vertex field is in proper registration with accompanying isocentric transverse fields. Errors can be identified rapidly and corrections made with no inconvenience to the patient.

Outcome for children with medulloblastoma treated with radiation and cisplatin, CCNU, and vincristine chemotherapy.

It has previously been reported in a single-institution trial that progression-free survival of children with medulloblastoma treated with radiotherapy and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), cisplatin, and vincristine chemotherapy during and after radiotherapy was better than the outcome in children treated with radiotherapy alone. To better characterize long-term outcome and duration of disease control, this treatment approach was used for 10 years and expanded to three institutions. Sixty-three children with posterior fossa medulloblastomas were treated with craniospinal local-boost radiotherapy and adjuvant chemotherapy with vincristine weekly during radiotherapy followed by eight 6-week cycles of cisplatin, CCNU, and vincristine. To be eligible for study entry, patients had to be older than 18 months of age at diagnosis and have a subtotal resection, evidence of metastatic disease, and/or brainstem involvement. Patients younger than 5 years of age and without these poor risk factors who received reduced-dose craniospinal radiotherapy (2400 cGy) were also eligible for entry into the study. Sixty-three of 66 eligible patients (95%) were entered and placed on this treatment regimen. Forty-two patients had brainstem involvement, 15 had metastatic disease at the time of diagnosis, and 19 had received a subtotal resection. Progression-free survival for the entire group at 5 years is 85% +/- 6%. Three children have succumbed to a second malignancy, and overall 5-year event-free survival is 83% +/- 6%. Progression-free survival was not adversely affected by younger age at diagnosis, brainstem involvement, or subtotal resection. Five-year actuarial progression-free survival for patients who received reduced-dose radiotherapy was similar to that for patients receiving conventional-dose radiotherapy. Patients with metastatic disease at the time of diagnosis had a 5-year progression-free survival rate of 67% +/- 15%, as compared to 90% +/- 6% for those patients with localized disease at the time of diagnosis (p = 0.037). The authors conclude that overall progression-free survival remains excellent for children with posterior fossa medulloblastomas treated with this drug regimen. Chemotherapy has a definite role in the management of children with medulloblastoma. Further studies are indicated to define which subpopulations of children with medulloblastoma benefit from chemotherapy and what regimens are optimum in increasing disease control and, possibly, in reducing the amount of radiotherapy required.

Failure of hyperfractionated radiotherapy to reduce bone growth arrest in rats.

PURPOSE: Radiotherapy of the craniospinal axis is causing an age dependent growth arrest in children. The purpose of this paper was to examine in an animal model, whether hyperfractionated radiotherapy, given with twice daily fractions in conventional overall treatment time, would cause less growth arrest of the spinal column than a regular treatment schedule. METHODS AND MATERIALS: The time-dose-fraction schedule for the treatment of the craniospinal axis of children with medulloblastomas was used as model for the treatment of the spine in rats. The entire spine of weanling rats received either 3570 cGy in 21 daily fractions of the 170 cGy, 5 times per week over 27 days, or 3630 cGy in 33 fractions of 110 cGy, given twice daily with 6-hr intervals over 21 days. RESULTS: Both fraction schedules were isoeffective and caused a growth inhibition of 9.5%. The growth arrest was complete after 1870-2420 cGy. The alpha/beta ratio for the growing rat vertebrae was 3400 cGy. This result contrasts with the growth sparing effect observed with hyperfractionation of accelerated treatment schedules. CONCLUSION: Growing bone is a fast proliferating tissue. Hyperfractionation with 110 cGy BID compared to 170 cGy given once a day, has no sparing effect on bone growth in rats if given in conventional overall treatment time.

Mediastinoscopy incisional metastasis. A radiotherapeutic approach.

Tumor seeding of the mediastinoscopy tract has been described. Although it is a rare occurrence, it can present the radiation oncologist with a therapeutic dilemma. Two cases of mediastinoscopy scar recurrences are reported. Their response to treatment and a review of previous cases are included.

Angiotensin-converting enzyme and other peptidolytic enzymes in human semen and relations to its spermatologic parameters.

Angiotensin-converting enzyme (ACE) and other enzymes of the renin-angiotensin system (RAS) occur in human semen in high activities. In contrast to bull ejaculates, not all zinc-dependent metallopeptidases are found to be in close correlation to the microscopically determined semen parameters; such a relationship was established only partly for the ACE. On the other hand, the RAS-dependent spermatozoa-bound enzymes, inclusive ACE, uniformly show negative correlations to the spermatologic parameters of human semen. These results, for the first time, point to different functions of the sperm-cell-bound (testicular) and of the seminal plasma (pulmonary) ACE activities.

Glioblastoma oncometry.

A prospective study of 20 patients was conducted to determine changes in the computed tomography appearance of glioblastomas seen at the completion of radiation therapy. An interval CT was obtained after 4000 to 4500 cGy to the whole brain and was compared to a similar baseline study. The tumor volume increased in twelve patients by 13 to 878% (mean 126%) and decreased in seven by 13 to 73% (mean 37%). It remained unchanged in one patient. A broadening or thinning of the enhancing rim frequently accompanied the increased or decreased tumor, respectively. Volume change immediately after whole brain radiotherapy was no prognostic indicator. The volume increase seen in 60% of the patients had implications for treatment planning of the boost field. It translated into a potential field size increase of up to 5.6 cm (mean 3.5 cm) and could contribute to a geographic miss. It is concluded that following whole brain radiation therapy, a repeat CT scan or magnetic resonance imaging, depending on the initial exam, is necessary for optimal planning of the reduced radiation field.

Occurrence and potential importance of angiotensin-converting enzyme in semen of boars.

The activities of angiotensin-converting enzyme (ACE) and leucinaminopeptidase (LAP) are positively correlated with corresponding concentrations of sperm cells in semen of boars kept under normal conditions. The spermatozoa bound ACE activity, in general, does not reflect differences in the quality of semen (bull and boars). On the other hand, the ACE activity directly bound on the sperm cells is significantly elevated, if 'exogenic noxes' (by feeding or keeping) influence the fertility of boars in a drastic manner. These results are discussed with regard to the differential diagnostic importance for estimating the semen quality and to the causal relations between increased enzyme binding and injury of sperm cells.

Occurrence and potential importance of selected peptidases in bull ejaculates.

The zinc containing peptidases angiotensin-converting enzyme (ACE), neutral metalloendopeptidase (NEP), and leucine aminopeptidase (LAP) occur in bull ejaculates in high activities. These enzyme activities are in close correlation with some routineously determined semen parameters. These ejaculat parameters are used for quality classification and selection of ejaculates and are according to long term experience in good correlation to the male fertility. Semen quality related correlations could not be found for the dipeptidyl aminopeptidase (DPIV) and the aminopeptidase A (APA). Origin and possible function of the zinc containing peptidases in the semen are examined and discussed.

[Possible involvement of the renin-angiotensin system in reproduction. I. Occurrence and role in the male reproductive tract]. / Zur möglichen Mitbeteiligung des Renin-Angiotensin-Systems am Fortpflanzungsgeschehen. I. Vorkommen und Rolle im männlichen Reproduktionstrakt.

With regard to the blood pressure the regulative function of the renin-angiotensin-system (RAS) is well known. Knowledge of the last years is that components of the RAS are available also in organs and excrets of the male reproductive tract. So, the angiotensin-converting-enzyme (ACE) - a key enzyme of the RAS - exists in the testes in an extraordinary high activity exceeding those of the lung tissue. In the ejaculate this so-called "testicular ACE" is associated with sperms, whereas the seminal plasma contains the higher molecular "pulmonary ACE". Because both isoenzymes posses the same catalytic effectiveness, the occurrence of adequate substrates (angiotensin I, bradykinin) and degrading products as effectors (angiotensin II), respectively, is of high importance for the valuation of the physiological relevance of the RAS in the process of fertility. Up to date, the knowledge is still insufficient, partly even contradictory. Therefore at present the regulative function(s) of the RAS in the male reproductive tract can only be expressed as postulates.

[Possible involvement of the renin-angiotensin system in reproduction. II. Occurrence and role in the female reproductive tract]. / Zur möglichen Mitbeteiligung des Renin- Angiotensin-Systems am Fortpflanzungsgeschehen. II. Vorkommen und Rolle im weiblichen Reproduktionstrakt.

Biochemical and immunological studies of the last years reveal the existence of an "ovarian renin-angiotensin system (RAS)". Despite of the low angiotensin-conterting enzyme (ACE) activity in the ovary the follicular fluid is rich in angiotensin II (AII). The detection of AII receptors on cells within maturating follicles proves them as AII targets. Therefore, it is supposed that AII may be involved in the regulation of fundamental processes of follicle maturation and/or corpus luteum formation. Further interesting findings are the high concentration of prorenin in the follicle fluid of women causing an increase of the prorenin blood plasma level at time of ovulation, and a second increase of the blood prorenin concentration in the middle of the luteal phase. With respect to the ACE activity in the ejaculate it is imaginable that the smooth muscle tonus of the uterus and the oviduct could be affected by local generation von AII and/or degradation of bradykinin and thus the transit of the semen may be facilitated. Further systematic research is necessary to bring more light into the physiological context and to replace hypothetical interpretations of the findings by exact knowledge.