In situ structural analysis of calcium aluminosilicate glasses under high pressure

In situ micro-Raman spectroscopy was used to investigate the structural evolution of OH(-)-free calcium aluminosilicate glasses, under high pressure and at room temperature. Evaluation was made of the role of the SiO2 concentration in percalcic join systems, for Al/(Al  +  Si) in the approximate range from 0.9 to 0.2. Under high pressure, the intensity of the main band related to the bending mode of bridging oxygen ([Formula: see text][T-O-T], where T  =  Si or Al) decreased gradually, suggesting that the bonds were severely altered or even destroyed. In Si-rich glasses, compression induced a transformation of Q (n) species to Q (n-1). In the case of Al-rich glass, the Al in the smallest Q (n) units evolved from tetrahedral to higher-coordinated Al (([5])Al and ([6])Al). Permanent structural changes were observed in samples recovered from the highest pressure of around 15 GPa and, particularly for Si-rich samples, the recovered structure showed an increase of three-membered rings in the Si/Al tetrahedral network.

Functional antagonism between nociceptin/orphanin FQ and corticotropin-releasing factor in rat anxiety-related behaviors: involvement of the serotonergic system

Nociceptin/orphanin FQ (N/OFQ) acts as an anxiolytic-like agent in the rat and behaves as a functional antagonist of corticotropin-releasing factor (CRF) due to its ability to oppose CRF biological actions. In response to stress, CRF triggers changes in neurotransmitter systems including serotonin (5-HT). The role of 5-HT1A receptor in anxiety has been supported by preclinical and clinical studies. The present study investigated the possible functional antagonism between N/OFQ (1nmol/rat) and CRF (0.2nmol/rat) in anxiety-related conditions in rats, using elevated plus maze and defensive burying tests, in order to confirm previous literature results. Moreover, possible changes in the serotonergic system were studied in areas rich of serotonergic neurons: frontal cortex and pons. In both tests N/OFQ showed anxiolytic-like effects while CRF displayed anxiogenic-like effects. N/OFQ before CRF treatment counteracted the anxiogenic-like effects evoked by CRF. In frontal cortex, N/OFQ significantly decreased 5-HT levels but did not modify the hydroxyindoleacetic acid (5-HIAA) ones; CRF modified neither 5-HT nor 5-HIAA content but counteracted changes induced by N/OFQ alone. In pons, N/OFQ induced no change in serotonergic activity while CRF significantly decreased 5-HT levels and increased 5-HIAA content. The two peptides' combination reinstated serotonergic parameters to controls. In frontal cortex, N/OFQ increased the 5HT1A receptor density but reduced its affinity, while CRF alone did not induce any change. In pons, CRF decreased 5HT1ABmax and KD whereas N/OFQ was ineffective. All biochemical modifications were reverted by N/OFQ plus CRF treatment. The present study confirms that N/OFQ counteracts CRF anxiogenic-like effects in the behavioral tests evaluated. These effects may involve central serotonergic mechanisms since N/OFQ plus CRF induces a reversion of serotonergic changes provoked by single peptide. Our data support the hypothesis that N/OFQ may behave as functional CRF antagonist, this action being of interest for the treatment of anxiety disorders.

Effect of acute and repeated administration of paracetamol on opioidergic and serotonergic systems in rats

OBJECTIVE AND DESIGN

We investigated the antinociceptive effect of paracetamol or morphine after repeated administration and the changes in the characteristics of central mu-, kappa- and 5-HT2 receptors.

TREATMENT

Male rats were injected twice a day for seven days with paracetamol (400 mg/kg, i. p.) or morphine (5 mg/kg, s. c.).

METHODS

The antinociceptive effect was evaluated 30 min after single and multiple doses of paracetamol and morphine through the hot-plate test. Binding techniques were used to evaluate the receptor characteristics in the frontal cortex.

RESULTS

Both paracetamol and morphine induced an antinociceptive effect on day 1 but only paracetamol maintained this effect for seven days while morphine did not. The number of mu-opioid receptors decreased on days 1, 3, and 7 by a similar percentage after paracetamol administration (by 29, 31 and 34 %, respectively), while morphine produced a progressive decrease in comparison with controls (by 37, 49 and 60 %, respectively) and kappa-opioid receptors were unaffected. Both drugs similarly decreased the 5-HT2 receptor number on all days of treatment (by about 30 %).

CONCLUSIONS

The opioidergic and serotonergic systems are involved in different ways in the induction and maintenance of antinociception after paracetamol or morphine treatment.

Differential involvement of central 5-HT 1B and 5-HT 3 receptor subtypes in the antinociceptive effect of paracetamol

OBJECTIVE

We investigated the effect of pre-treatment with ondansetron or CP 93129 (a 5-HT1B agonist) on the antinociceptive activity of paracetamol and the changes in central 5-HT3 receptors induced by paracetamol alone or co-administered with ondansetron.

MATERIALS AND SUBJECTS

Male Wistar rats (eight per group) were injected with ondansetron (2 and 4 mg/kg s.c.) or CP 93129 (0.5, 1 and 2 mg/kg s.c.) 15 min before paracetamol (400 mg/kg, i.p.).

METHODS

Pain threshold was evaluated in the hot-plate or in the paw pressure test 30 min after the last treatment. 5-HT3 receptor binding capacity was measured in the frontal cortex, temporal-parietal cortex and midbrain by means of radioligand binding technique. Statistical analysis was done using ANOVA followed by Student-Newman-Keuls test and 2X2 factorial analysis when appropriate.

RESULTS

Pre-treatment with ondansetron, at doses of 2 and 4 mg/kg, did not affect the antinociceptive activity of paracetamol in the hot-plate test and in the paw pressure test. Paracetamol did not change the characteristics of 5-HT3 receptors in all the areas investigated. Ondansetron (4 mg/kg s.c.) per se significantly increased the 5-HT3 receptor number in the areas used, the effect not being modified by co-administration with paracetamol. On the other hand, CP 93129 (2 mg/kg s.c.) significantly prevented the effect of paracetamol in both algesimetric tests used.

CONCLUSIONS

Our data indicate that 5-HT1B but not 5-HT3 receptors are involved in the antinociceptive effect of paracetamol in our experimental conditions.

The role of the left frontal lobe in action naming: rTMS evidence

BACKGROUND

Neuropsychological and neuroimaging studies suggest that whereas the left temporal neocortex plays a crucial role in all tasks involving lexical-semantic processing, some regions of the left prefrontal convexity are selectively recruited during verb processing.

OBJECTIVE

To determine if there are different neural correlates for noun and verb processing in the human brain.

METHODS

Repetitive transcranial magnetic stimulation (rTMS), 20 Hz at 90% of the motor threshold, was applied to left or right prefrontal brain during object- and action-naming tasks in nine healthy subjects.

RESULTS

A shortening of naming latency for actions was observed only after stimulation of left prefrontal cortex.

CONCLUSION

The involvement of the left dorsolateral frontal cortex in action naming was demonstrated using rTMS.

Selective COX-2 inhibitors and dual acting anti-inflammatory drugs: critical remarks

Non steroidal anti-inflammatory drugs (NSAIDs) are still the most commonly used remedies for rheumatic diseases. But NSAIDs produce serious adverse effects, the most important being gastric injury up to gastric ulceration and renal damage. Several strategies have been adopted in order to avoid these shortcomings, especially gastrointestinal toxicity. So, non steroidal anti-inflammatory drugs have been associated with gastroprotective agents that counteract the damaging effects of prostaglandin synthesis suppression: however, a combination therapy introduces problems of pharmacokinetics, toxicity, and patient s compliance. Also incorporation of a nitric oxide (NO)-generating moiety into the molecule of several NSAIDs was shown to greatly attenuate their ulcerogenic activity: however, several findings suggest a possible involvement of NO in the pathogenesis of arthritis and subsequent tissue destruction. A most promising approach seemed to be the preparation of novel NSAIDs, specific for the inducible isoform of cyclooxygenase (COX-2): they appear to be devoid of gastrointestinal toxicity, in that they spare mucosal prostaglandin synthesis. However, a number of recent studies raised serious questions about the two central tenets that support this approach, namely that the prostaglandins that mediate inflammation and pain are produced solely via COX-2 and that the prostaglandins that are important in gastrointestinal and renal function are produced solely via COX-1. So, increasing evidence shows that COX-2 (not only COX-1) also plays a physiological role in several body functions and that, conversely, COX-1 (not only COX-2) may also be induced at sites of inflammation. Moreover, COX-2 selective NSAIDs have lost the cardiovascular protective effects of non-selective NSAIDs, effects which are mediated through COX-1 inhibition (in addition, COX-2 has a role in sustaining vascular prostacyclin production). The products generated by the 5-lipoxygenase pathway (leukotrienes) are particularly important in inflammation: indeed, leukotrienes increase microvascular permeability and are potent chemotactic agents; moreover, inhibition of 5-lipoxygenase indirectly reduces the expression of TNF-alpha (a cytokine that plays a key role in inflammation). This explains the efforts to obtain drugs able to inhibit both 5-lipoxygenase and cyclooxygenases: the so-called dual acting anti-inflammatory drugs. Such compounds retain the activity of classical NSAIDs, while avoiding their main drawbacks, in that curtailed production of gastroprotective prostaglandins is associated with a concurrent curtailed production of the gastro-damaging and bronchoconstrictive leukotrienes. Moreover, thanks to their mechanism of action, dual acting anti-inflammatory drugs could not merely alleviate symptoms of rheumatic diseases, but might also satisfy, at least in part, the criteria of curative drugs. Indeed, leukotrienes are pro-inflammatory, increase microvascular permeability, are potent chemotactic agents and attract eosinophils, neutrophils and monocytes into the synovium. Finally, recent data strongly suggest that dual inhibitors may have specific protective activity also in neurodegeneration.

Effect of rofecoxib on nociception and the serotonin system in the rat brain

OBJECTIVE AND DESIGN

The purpose of the present study was to determine whether the antinociceptive activity of rofecoxib is mediated, at least in part, through changes in the brain serotonergic system.

MATERIALS AND SUBJECTS

Male Wistar rats weighing 180-200 g (groups of eight) were subjected to the hot-plate and formalin tests after rofecoxib treatment. Cortical areas were removed for serotonin (5-HT) level, 5-HT2 and mu-receptor evaluation.

TREATMENT

Rofecoxib was administered orally at doses of 5, 10, 20 and 50 mg/kg for the time course evaluation in the hot-plate test (30, 60 and 120 min), and at the dose of 10 mg/kg for the formalin test and biochemical determinations.

METHODS

The tests performed were the hot-plate and the formalin assays. HPLC was used to determine 5-HT levels and radioligand-binding assays were utilized to evaluate the characteristics of 5-HT2 and mu-receptors. The data were analysed by ANOVA or Student's t test.

RESULTS

The lowest active dose of rofecoxib in the hot-plate test was 10 mg/kg. The percentage of the maximum possible effect (%MPE) values were: control = 1.7+/-3.4; treated 23.4+/-6.5 (p<0.05). The same dose had a significant effect on both phases of the formalin test. Pretreatment with p-chlorophenylalanine (PCPA) significantly decreased the activity of rofecoxib in the hot-plate test. Rofecoxib treatment increased serotonin levels and decreased the maximum number of 5-HT2 receptors. 5-HT levels (ng/g) were: control = 240.1 +/- 28.5, rofecoxib = 326.1 +/- 19.9 in the frontal cortex. The characteristics of mu-receptors did not change.

CONCLUSIONS

These results suggest that rofecoxib may exert its therapeutic effect, at least in part, through the central serotonergic system. The opioidergic system, on the other hand, seems to be unaffected.

Dual acting anti-inflammatory drugs: a reappraisal

Rheumatic diseases are the most prevalent causes of disability in western countries, and non-steroidal anti-inflammatory drugs (NSAIDs) are still the most commonly used remedies. However, NSAIDs cause several serious adverse effects, the most important being from gastric injury to gastric ulceration and renal damage. Attempts to develop non-steroidal anti-inflammatory remedies devoid of these shortcomings-especially gastrointestinal toxicity-have followed several strategies. Non-steroidal anti-inflammatory drugs have, therefore, been associated with gastroprotective agents that counteract the damaging effects of prostaglandin synthesis suppression; however, a combination therapy introduces other problems of pharmacokinetics, toxicity, and patient's compliance. More recently, incorporation of a nitric oxide (NO)-generating moiety into the molecule of several NSAIDs was shown to greatly attenuate their ulcerogenic activity; however, several findings suggest a possible involvement of NO in the pathogenesis of arthritis and subsequent tissue destruction. A most promising approach seemed to be the preparation of novel NSAIDs, targeted at the inducible isoform of prostaglandin synthase (COX-2); they appear to be devoid of gastrointestinal toxicity, in that they spare mucosal prostaglandin synthesis. However, a number of recent studies have raised serious questions about the two central tenets that support this approach, namely that the prostaglandins that mediate inflammation and pain are produced solely via COX-2 and that the prostaglandins that are important in gastrointestinal and renal function are produced solely via COX-1. So, a growing body of evidence shows that COX-2 (not only COX-1) also plays a physiological role in several body functions and that, conversely, COX-1 (not only COX-2) may also be induced at sites of inflammation. More recent and puzzling data shows that COX-2 is induced during the resolution of an inflammatory response, and at this point it produces anti-inflammatory (PGD2 and PGF2alpha), but not proinflammatory (PGE2) prostaglandins; inhibition of COX-2 at this point thus results in persistence of the inflammation. Moreover, COX-2 selective NSAIDs have lost the cardiovascular protective effects of non-selective NSAIDs, effects which are mediated through COX-1 inhibition (in addition, COX-2 has a role in sustaining vascular prostacyclin production). The generation of other very important products of the arachidonic acid cascade (besides cyclooxygenase-produced metabolites) is inhibited neither by non-selective nor by COX-2 selective NSAIDs. The products generated by the 5-lipoxygenase pathway (leukotrienes) are particularly important in inflammation; indeed, leukotrienes increase microvascular permeability and are potent chemotactic agents. Moreover, inhibition of 5-lipoxygenase indirectly reduces the expression of TNF-alpha (a cytokine that plays a key role in inflammation). These data and considerations explain the efforts to obtain drugs able to inhibit both 5-lipoxygenase and cyclooxygenases, the so-called dual acting anti-inflammatory drugs. Such compounds retain the activity of classical NSAIDs, while avoiding their main drawbacks, in that curtailed production of gastroprotective prostaglandins is associated with a concurrent curtailed production of the gastro-damaging and bronchoconstrictive leukotrienes. Moreover, thanks to their mechanism of action, dual acting anti-inflammatory drugs could not merely alleviate symptoms of rheumatic diseases, but might also satisfy, at least in part, the criteria of a more definitive treatment. Indeed, leukotrienes are pro-inflammatory, increase microvascular permeability, are potent chemotactic agents and attract eosinophils, neutrophils and monocytes into the synovium.

Clinical aspects of peritoneal sclerosis

Peritoneal sclerosis (PS) occurs in various clinical situations in Peritoneal Dialysis (PD) patients. Some degree of PS is often present in long-term PD patients, generally without clinical or functional consequences. At the other end of the spectrum of PS there is Sclerosing encapsulating peritonitis (SEP). Though infrequent, it is very severe. SEP is not a complication exclusive to PD; it is a syndrome related to many diseases of abdominal organs, some drugs and abdominal surgery. Remarkably, in many cases, the first symptoms of SEP appear months or years after the change from PD to HD has occurred. Today there is no full agreement about the microscopical findings of SEP or about the name of this syndrome: SEP or Encapsulating Peritoneal Sclerosis (EPS). The main etiopathogenetic factor for PS is the poor biocompatibility of PD solutions. In the etiopathogenesis of SEP, other factors in addition to the PD fluids have been suggested as possible causes (peritonitis, drugs, disinfectants, etc.). This paper reviews all the clinical aspects of PS and SEP: pathogenesis, clinical signs, diagnosis and therapy.

Long-term follow-up of patients treated for chronic headache with analgesic overuse

The study aim is to describe the long-term clinical outcome of 102 chronic headache patients with analgesic daily use. They were assessed for daily drug intake (DDI), headache index (HI) and quality of life (QoL) and compared with a parallel group of patients with active chronic daily headache but no analgesic overuse. For the primary study group, baseline 1995 DDI was 1.80 +/- 1.87 and did not differ significantly in 1999. Patients who daily continued to use analgesics had a higher 1995 baseline DDI (t = 2.275, P = 0.025), a longer drug abuse history (t = 2.282, P = 0.025) and a higher DDI (t = 4.042, P < 0.001) 4 years later. At 4 years of follow-up, only one-third of patients initially treated for chronic daily headache and analgesic overuse are successful in refraining from chronic overuse. Those subjects appear to have a persistence for combination analgesic agents; however, their QoL is slightly better than that of patients who revert to episodic headache or continue with chronic daily headache but do not overuse analgesic agents. Persistent analgesic overuse seems to be linked to the length of abuse and to the number of drugs ingested.

Number-Stroop performance in normal aging and Alzheimer's-type dementia

The number-Stroop paradigm was used to investigate changes in the inhibitory system and in numerical processing in healthy elderly and individuals with dementia of Alzheimer's type (DAT). The size-congruity effect (i.e., relative to neutral trials, incongruent pairs interfere and/or congruent pairs facilitate either numerical or physical comparison) was found in all groups, though the pattern of interference and facilitation varied across them. Overall, the selective attention breakdown was reflected by the increase in interference shown by the older group and the DAT group. On the other hand, the observation of a standard laterality effect andof automatic numerical processing in all groups suggests that access and retrieval of numerical information is relatively resistant to cognitive deterioration.

The effect of a paracetamol and morphine combination on dynorphin A levels in the rat brain

The purpose of this study was to find out whether the combination of inactive doses of paracetamol (PARA) and morphine was able to change dynorphin (DYN) A levels, evaluated by radioimmunoassay, and whether naloxone or [(-)-2-(3 furylmethyl)-normetazocine] (MR 2266), a kappa-opioid antagonist, modifies or prevents the activity of this combination on nociception and on DYN levels. The work was suggested by our previous findings which demonstrated that inactive doses of PARA and morphine, when given in combination, share an antinociceptive effect, and that PARA, at antinociceptive doses, decreases DYN levels in the frontal cortex, thus indicating a selective action within the CNS. Our present results demonstrate that the combination of inactive doses of PARA (100 mg/kg) and morphine (3 mg/kg) is just as effective in decreasing the levels of DYN A as full antinociceptive doses of PARA or morphine alone in the frontal cortex of the rat. The values, expressed in pmol/g tissue, were: control = 2.83 +/- 0.20; paracetamol (100) = 2.60 +/- 0.23; morphine (3) = 2.73 +/- 0.24; paracetamol + morphine = 1.34 + 0.16 (P < 0.05). The decrease was partially antagonised by MR 2266, but not by naloxone, suggesting that the activity of PARA and morphine in combination on DYN A levels could be mediated, at least in part, through kappa-receptors, although other systems may be involved. On the other hand, both naloxone and MR 2266 prevented the antinociceptive effect of the combination in the hot plate test. All our experimental data suggest that PARA and morphine in combination exert their antinociceptive effect through the opioidergic system, which in turn may cause a decrease in DYN levels in the CNS of the rat.

The effect of paracetamol on nociception and dynorphin A levels in the rat brain

Male Wistar rats were administered with naloxone (1 mg/kg i.p.) or MR 2266 (5 mg/kg i.p) 15 min before paracetamol (400 mg/kg i.p.) treatment and the pain threshold was evaluated. Rats were subjected to the hot-plate and formalin tests and immunoreactive dynorphin A (ir-dynorphin A) levels were measured in the hypothalamus, hippocampus, striatum, brainstem, frontal and parietal-temporal cortex by radioimmunoassay. Pretreatment with naloxone abolished paracetamol antinociceptive activity both in hot-plate and in the first phase, but not in the second phase of the formalin test, while MR 2266 pretreatment was able to antagonise paracetamol effect either in the hot-plate test or in both phases of the formalin test. Among different brain areas investigated paracetamol significantly decreased ir-dynorphin A levels only in the frontal cortex. MR 2266 but not naloxone reversed the decrease in ir-dynorphin A levels elicited by paracetamol. Paracetamol seems to exert its antinociceptive effect also through the opioidergic system modulating dynorphin release in the central nervous system (CNS) of the rat, as suggested by the decrease in the peptide levels.

Adequacy of dialysis reduces the doses of recombinant erythropoietin independently from the use of biocompatible membranes in haemodialysis patients

BACKGROUND

The effect of the adequacy of dialysis on the response to recombinant human erythropoietin (rHuEpo) therapy is still incompletely understood because of many confounding factors such as iron deficiency, biocompatibility of dialysis membranes, and dialysis modality that can interfere.

METHODS

We investigated the relationship between Kt/V and the weekly dose of rHuEpo in 68 stable haemodialysis (HD) patients (age 65+/-15 years) treated with bicarbonate HD and unsubstituted cellulose membranes for 6-343 months (median 67 months). Inclusion criteria were HD for at least 6 months, subcutaneous rHuEpo for at least 4 months, transferrin saturation (TSAT) > or = 20%, serum ferritin > or = 100 ng/ml, and haematocrit (Hct) level targeted to 35% for at least 3 months. Exclusion criteria included HBsAg and HIV positivity, need for blood transfusions or evidence of blood loss in the 3 months before the study, and acute or chronic infections. Hct and haemoglobin (Hb) levels were evaluated weekly for 4 weeks; TSAT, serum ferritin, Kt/V, PCRn, serum albumin (sAlb), and weekly dose of rHuEpo were evaluated at the end of observation. No change in dialysis or therapy prescription was made during the study.

RESULTS

The results for the whole group of patients were: Hct 35 +/- 1.2%, Hb 12.1 +/- 0.6 g/dl, TSAT 29 +/- 10%, serum ferritin 204 +/- 98 ng/ml, sAlb 4.1 +/- 0.3 g/dl, Kt/V 1.33 +/-0.19, PCRn 1.11+/- 0.28 g/kg/day, weekly dose of rHuEpo 123 +/- 76 U/kg. Hct did not correlate with Kt/V, whereas rHuEpo dose and Kt/V were inversely correlated (r = -0.49; P < 0.0001). Multiple regression analysis with rHuEpo as dependent variable confirmed Kt/V as the only significant variable (P < 0.002). Division of the patients into two groups according to Kt/V (group A, Kt/V < or = 1.2; group B, Kt/V > or = 1.4), showed no differences in Hct levels between the two groups, while weekly rHuEpo dose was significantly lower in group B than in group A (group B, 86 +/- 33 U/kg; group A, 183 +/- 95 U/kg, P < 0.0001).

CONCLUSIONS

In iron-replete HD patients treated with rHuEpo in the maintenance phase, Kt/V exerts a significant sparing effect on rHuEpo requirement independent of the use of biocompatible synthetic membranes. By optimizing rHuEpo responsiveness, an adequate dialysis treatment can contribute to the reduction of the costs of rHuEpo therapy.

Familial clustering of IgA nephropathy: further evidence in an Italian population

Several lines of evidence suggest that genetic factors have an important role in the pathogenesis of immunoglobulin A (IgA) nephropathy. We report the prevalence of familial IgA nephropathy in a referral center in northern Italy and present the data on HLA genotypes in the families identified. Twenty-six of 185 patients (14%) with IgA nephropathy investigated in Brescia, Italy, were related to at least one other patient with the disease. Restriction fragment length polymorphism (RFLP) analysis of HLA-DR beta and HLA-DQ alpha and beta genes, as well as polymerase chain reaction-based oligonucleotide typing, was performed in family members. The 26 patients with IgA nephropathy belonged to 10 families. Familial relationships between the patients varied greatly, ranging from parent-child to sib-pair to more distant familial relationships. No common nephrotoxic factor was identified in the families. The intervals separating the apparent onset of disease in relatives with IgA nephropathy varied from 8 months to 13 years. In patients with a family history of IgA nephropathy, there was an increased incidence of HLA-DRB1*08 compared with those with sporadic IgA nephropathy. The study shows that a significant number of the patients with IgA nephropathy followed up in Brescia had a family history of disease. The fact that the Italian population, an ethnic group not previously examined, also presents an increased familial susceptibility to IgA nephropathy suggests that familial predisposition is a very common finding for IgA nephropathy. Thus, clinicians should become aware that IgA nephropathy may aggregate within families in a substantial number of cases. In addition, this subgroup of patients with IgA nephropathy offers an ideal opportunity to elucidate the molecular genetics of this disease.

The potentiation of analgesic activity of paracetamol plus morphine involves the serotonergic system in rat brain

OBJECTIVE AND DESIGN

We investigated the antinociceptive effect of subactive doses of paracetamol and morphine, given in combination.

MATERIAL AND TREATMENT

Male Wistar rats were injected with paracetamol (50 or 100 mg/kg i.p.) and morphine (2, 3 or 5 mg/kg s.c.) 10 min later and subjected to algesimetric tests 20 min thereafter.

METHODS

Pain threshold was evaluated in the hot-plate and formalin tests. 5-HT2 receptor binding capacity and 5-HT and 5-HIAA levels were measured in cortical and pontine areas of the brain by means of radioligand binding technique and by HPLC, respectively. Statistical analysis was done using Student-Neuman-Keul's test and 2 x 2 factorial analysis.

RESULTS

Only when given in combination, paracetamol (100 mg/kg) and morphine (2 and 3 mg/kg) were able to evoke an antinociceptive effect in both tests associated with an increase in 5-HT levels and a decrease in 5-HT2 receptors in the cortex. These effects were prevented by i.p. pretreatment with naloxone (1 mg/kg i.p.).

CONCLUSIONS

Subactive doses of paracetamol and morphine exert an analgesic effect when given in combination in the rat and indicate an involvement of both serotonergic and opiatergic systems.

Effect of acetylsalicylic acid on formalin test and on serotonin system in the rat brain

1. Acetylsalicylic acid (ASA; 400 mg/kg, i.p.) increased serotonin (5-HT) content in rat brain but did not modify the number or the affinity of 5-HT1A receptors in the pons and the cerebral cortex, whereas the number of cortical 5-HT2 receptors decreased significantly. 2. Pretreatment with parachlorophenylaline (100 mg/kg/day for 4 days) depleted 5-HT brain content but modified neither the serum levels of salicylates nor the 5-HT2 cortical receptor characteristics, and it abolished the antinociceptive effect of ASA, 400 mg/kg, in the first phase of the formalin test. 3. These data support the involvement of the central serotonergic system in the antinociceptive activity of ASA.

Acetylsalicylic acid potentiates the antinociceptive effect of morphine in the rat: involvement of the central serotonergic system

Acetylsalicylic acid and morphine are the most widely distributed and most frequently used drugs in the relief of pain, but their analgesic activity has adverse side-effects. Mixtures containing these two drugs are frequently used to relieve mild to moderate pain despite the paucity of relevant experimental evidence so far published. We set out to study the possible antinociceptive effect of a combination of subactive doses of the two drugs in rats. A combination of low doses of acetylsalicylic acid (50 mg/kg i.p.) and morphine (3 mg/kg s.c.) was administered and the pain threshold was evaluated in the hot-plate and formalin tests, and 5-HT2 receptor binding capacity, 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels were measured in the cortex and pontine areas of the brain. The combination of acetylsalicylic acid and morphine had an analgesic effect in both tests that was associated with an increase in 5-HT levels and a decrease in 5-HT2 receptors in the cortex. These effects were either completely abolished or partially prevented by i.p. pretreatment with naloxone (1 mg/kg i.p.). Our results demonstrate that subactive doses of acetylsalicylic acid and morphine can exert analgesic and biochemical effects when given in combination in the rat and suggest an involvement of serotonergic and opiatergic systems.

Naloxone-reversible antinociception by paracetamol in the rat

Paracetamol at the dose of 400 mg/kg i.p. displayed antinociceptive activity in the hot-plate test and the formalin test. Moreover, it induced a significant increase in brain serotonin (5-HT) concentration and a reduction in the number of 5-HT2 receptors in cortical membranes. Pretreatment with naloxone abolished this antinociceptive activity both in the hot-plate test and in the first phase of the formalin test without affecting the serum concentration of paracetamol. At the same time, naloxone prevented the increase in 5-HT concentration in the central nervous system and the reduction in 5-HT2 receptors in cortical membranes. Competition experiments demonstrated that paracetamol possesses affinity for [3H]naloxone binding sites. The action of morphine on nociception and on the serotonergic system was similar to that of paracetamol; all morphine-induced effects were blocked by naloxone. These data provide further evidence for a central antinociceptive effect of paracetamol and support the hypothesis that paracetamol exerts its antinociceptive activity through the serotonergic system. Moreover, our results point to the relationship between serotonergic and opiatergic systems in the antinociceptive activity of paracetamol.

Serotonin and opiate involvement in the antinociceptive effect of acetylsalicylic acid

Acetylsalicylic acid (ASA), 400 mg/kg i.p., displayed antinociceptive activity in both the hot-plate and the formalin test. ASA significantly increased brain serotonin (5-HT) content and reduced the number of 5-HT2 receptors in cortical brain membranes 30 min after drug administration. Pretreatment with naloxone abolished the antinociceptive activity of both ASA and morphine in the hot-plate and formalin tests and prevented the increase in cerebral 5-HT concentration and the reduction in 5-HT2 receptors in cortical membranes induced by ASA. The serum salicylate concentrations were not affected by pretreatment with naloxone. These data indicate a central antinociceptive activity of ASA and suggest that ASA may exert its antinociceptive action through serotonergic and opiatergic pathways.

Streptozotocin-induced diabetes provokes changes in serotonin concentration and on 5-HT1A and 5-HT2 receptors in the rat brain

Since reduced levels of brain serotonin are known to cause behavioural abnormalities, to which diabetics are also prone, we investigated the effect, in rats, of chronic diabetes on brain serotonin concentration and on the numbers of 5-HT(1A) and 5-HT2 receptors in cerebral cortex and brainstem. Our data show that streptozotocin induces a longlasting hyperglicemia that is associated with a decrease in cerebral concentration of serotonin and with an accompanying increase in the maximum number of 5-HT(1A) and 5-HT2 receptors in the brain areas studied. Our results may suggest that changes in serotonergic transmission in the CNS play a role in diabetes-related behavioural abnormalities.

The antinociceptive action of paracetamol is associated with changes in the serotonergic system in the rat brain

The antinociceptive activity of paracetamol in the hot plate and formalin tests was studied to establish the relationship between antinociceptive activity and the central serotonergic system. Significant antinociceptive activity of paracetamol was observed in the formalin test at the dose of 300 mg/kg, while, at the dose of 400 mg/kg, the drug was active both in the formalin and in the hot-plate test. Serum paracetamol levels remained sub-toxic and the behavioral profile remained unchanged. Depletion of brain serotonin with p-chlorophenylalanine prevented the antinociceptive effect of paracetamol in the hot-plate test and in the first phase of the formalin response. Paracetamol significantly increased the serotonin content in the pontine and cortical areas (by 75 and 70%, respectively). The pretreatment with p-chlorophenylalanine reduced the 5-hydroxytryptamine (5-HT) content in cortical and pontine areas to 12 and 19% of baseline values, respectively, and prevented the enhancement induced by paracetamol. The maximum number of cortical 5-HT2 receptors was reduced by paracetamol, while the number of 5-HT1A receptors in both cortical and pontine areas was unchanged. Pre-treatment with p-chlorophenylalanine prevented the reduction in the number of 5-HT2 receptors induced by paracetamol. These results provide evidence for the involvement of the central serotonergic system in the antinociceptive effect of paracetamol in the hot plate and formalin tests.

A prospective comparison of bicarbonate dialysis, hemodiafiltration, and acetate-free biofiltration in the elderly

Hemodiafiltration (HDF) and more recently acetate-free biofiltration (AFB) have shown good blood purification and cardiovascular stability in young and middle-aged hemodialysis patients. It is not clear if this is also valid for elderly patients. Twelve patients aged more than 70 years (mean age +/- SD, 76 +/- 4 years) on regular dialysis for at least 5 months were treated with bicarbonate dialysis (BD), HDF, or AFB in a randomized sequence and prospectively followed for 6 months (72 dialysis sessions/patient) for each procedure. The dialysis solution (containing bicarbonate), blood flow rate, and dialysate flow rate were the same with all the methods. During HDF and AFB solutions containing bicarbonate at a concentration of 27 to 30 mEq/L and 145 mEq/L, respectively, were infused postdilution at a rate of 66 +/- 7 mL/min and 2.81 +/- 0.12 L/hr, respectively. During the period of observation we evaluated the number of intradialytic hypotensions, the episodes of nausea, vomiting, headache (dialysis intolerance), body weight, the interdialysis weight gain, the duration of the dialysis session, the number of hospitalizations/patient, and the length of hospitalization/patient. At the end of each observation period we determined: Kt/V, protein catabolic rate, acid base balance, serum creatinine, serum calcium, serum phosphorus, alkaline phosphatases, and serum intact parathyroid hormone. After the switch from BD to either HDF or AFB, the results have shown a significant reduction of dialysis hypotension episodes (18 percent on BD, 14 percent on HDF, and 13 percent on AFB; BD v HDF, P = 0.001; BD v AFB, P = 0.0001; and HDF v AFB, P = NS) and of dialysis intolerance (3.3 percent on BD, 1.3 percent on HDF, and 1.1 percent on AFB; BD v HDF, P = 0.021; BD v AFB, P = 0.019; and HDF v AFB, P = NS). Kt/V improved significantly after the switch from BD to either HDF or AFB (1.17 +/- 0.06 on BD, 1.32 +/- 0.12 on HDF, and 1.32 +/- 0.13 on AFB; BD v HDF, P = 0.021; BD v AFB, P = 0.003; HDF v AFB, P = NS). Protein catabolic rate also improved in HDF and AFB compared with BD (0.90 +/- 0.12 on BD, 1.03 +/- 0.15 on HDF, and 1.04 +/- 0.14 on AFB; BD v HDF, P = 0.001; BD v AFB, P = 0.009; and HDF v AFB, P = NS). AFB showed a better correction of acidosis compared either with BD or HDF (serum bicarbonate, 20.3 +/- 1.1 mEq/L on BD, 20.8 +/- 2.2 mEqL on HDF, and 22.2 +/- 2.4 mEq/L on AFB; BD v HDF, P = NS; BD v AFB, P = 0.01; and HDF v AFB, P = 0.030). The other parameters observed did not differ. In conclusion HDF and AFB show a better dialysis efficiency and a better hemodynamic tolerance compared with BD. This fact is associated with an improvement in protein intake as assessed by kinetic criteria. Acetate-free biofiltration has the further advantage of a better control of the acid-base balance compared with BD and HDF. HDF and AFB are useful dialytic options to traditional BD hemodialysis even in patients older than 70 years.

Effect of acute and chronic treatment with triiodothyronine on serotonin levels and serotonergic receptor subtypes in the rat brain

Hyperthyroidism is often associated with behavioral disorders, and thyroid hormones modify receptor sensitivity as well as the synthesis and/or turnover rate of many neurotransmitters. We evaluated the influence in adult rats of triiodothyronine (T3), administered s.c. (100 micrograms/kg) acutely (once only) or chronically (once a day for 3 or 7 consecutive days), on brain serotonin concentration and on the density and affinity of two brain serotonin (5-HT) receptor subtypes mainly involved in behavioral effects. After both acute and chronic T3 treatment, serotonin levels increased in the cerebral cortex but not in the hippocampus. The density and affinity of 5-HT1A receptors (using [3H]-8-OH-DPAT as ligand) were not affected, while there was a significant decrease in the number of 5-HT2 receptors in the cerebral cortex (using [3H]ketanserin as ligand). This observation might indicate that thyroid hormones enhance 5-HT concentration in certain brain areas, thus causing a down-regulation of 5-HT2 receptors. The serotonergic system could be involved in the complex brain-neurotransmitter imbalance underlying hyperthyroidism-linked behavioral changes.

Effects of acetylsalicylic acid on serotonin brain receptor subtypes

1. The lysine salt of acetyl salicylic acid (ASA) at a dose equivalent to 400 mg/kg of acetyl salicylic acid (ASA) was intraperitoneally administered in rats. 2. After 30 and 120 min ASA did not modify the number of receptors nor the affinity of [3H] 8-OH-DPAT binding sites in pons and cerebral cortex. On the other hand, the receptor number in the cortex membranes decreased significantly using [3H] ketanserin as ligand, while the receptor number in the pontine membranes did not change. 3. These data support the involvement of central 5-HT receptors in the mode of action of ASA.

Influence of protein catabolic rate on nutritional status, morbidity and mortality in elderly uraemic patients on chronic haemodialysis: a prospective 3-year follow-up study

It has been recently reported that elderly chronic haemodialysis (CHD) patients have a reduced protein catabolic rate (PCRn) in spite of an adequate Kt/V. However until now the long-term consequences of this fact on the nutritional status, morbidity, and mortality were not known. This prospective study evaluates, over a period of 3 years, the effect of the reduced PCRn on some nutritional parameters, morbidity mortality in CHD patients older than 65 years with adequate and stable Kt/V. Over the period 1990-1993 we evaluated 42 CHD patients over 65 years (mean +/- SD 72 +/- 5 years). PCRn, total serum proteins, serum albumin concentration, body weight, body mass index (BMI) and serum transferrin were determined at the start of the study and followed yearly until the end of observation. The incidence of hospitalization/patient-year, the mortality rate and the causes of death were also recorded. All the patients were managed to maintain a Kt/V > 0.9 throughout the study. Twenty-two patients (Group A), mean age 70 +/- 4 years, completed the entire period of observation. Their Kt/V was 1.10 +/- 0.12, PCRn was 0.95 +/- 0.12 g/kg/day, and serum albumin concentration was 40.2 +/- 1.5 g/l, and these did not change significantly. The other parameters also remained stable over time. Twenty patients (Group B) died. Their mean age was 74 +/- 6 years. This group's Kt/V was 1.11 +/- 0.15, PCRn was 0.94 +/- 0.18 g/kg/day, and serum albumin concentration was 39 +/- 3.1 g/l, and there were no significant variations between the start and the end of observation for all the parameters studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Opening of brain potassium-channels inhibits the ACTH-induced behavioral syndrome in the male rat

In adult male rats, the intracerebroventricular (i.c.v.) injection of pinacidil, a potassium channel opener, at the doses of 100, 200 or 300 micrograms/rat, dose-dependently reduced the display of the most typical behavioral symptoms (excessive grooming, stretching, yawning, penile erections) induced by the i.c.v. administration of ACTH-(1-24) (4 micrograms/rat). These data indicate that the complex mechanism of the melanocortin-induced behavioral syndrome involves closure of potassium channels in target neurons, and provide further experimental support to the idea that melanocortins are functional antagonists of opioids.

Involvement of brain serotonergic system in the antinociceptive action of acetylsalicylic acid in the rat

The pain-threshold in the hot-plate test and serotonin (5-HT) receptor binding capacity in the cortex and pontine areas of rat brain were studied after intraperitoneal (ip) administration of acetyl salicylate of lysine equivalent to 400 mg/kg of acetylsalicylic acid (ASA). The antinociceptive activity of ASA was prevented by ip pre-treatment with Parachlorophenylalanine (PCPA) at the rate of 100 mg/kg/day for 4 days. PCPA pre-treatment increased the number of 5-HT receptors and abolished the ASA-induced reduction in 5-HT receptor binding capacity in the cortex but did not affect serum salicylate levels. These results provide support for the hypothesis that the antinociceptive action of ASA, at least in the hot-plate test, involves the central serotonergic system.

Lack of activity of ketorolac in hot-plate test and serotonin binding capacity of brain membranes in rats

An increasing number of observations indicate that prostaglandin synthesis inhibition is not a satisfactory explanation for the antinociceptive activity of the non-steroidal anti-inflammatory drugs. In the hot-plate test performed 1 or 2 h after ketorolac at 40, 70 and 100 mg/kg i.p., the drug does not display any significant antinociceptive activity. Nor, at the two higher doses used, does it affect the cortical and pontine serotonin binding capacity of rat brain membranes 2 h after treatment. The data suggest that this lack of anti-nociceptive activity in the hot-plate test is associated with the drug's inability to affect the central serotoninergic system.

Lack of influence of aromatase and 5 alpha-reductase inhibition on [3H]imipramine binding in the male rat brain

In intact adult male rats an inhibitor of aromatase and an inhibitor of 5 alpha-reductase did not change the characteristics of [3H]imipramine binding sites in cerebral cortex, hypothalamus, and hippocampus. Testosterone, estradiol and dihydrotestosterone prevented the effect of castration on the number of [3H]imipramine binding sites, but had no effect in non-castrated animals. These data suggest that testosterone and its major metabolites, estradiol and dihydrotestosterone, are equally effective with regard to imipramine binding sites.

Changes in partition of extracellular fluid volumes in anemic dialyzed uremic patients after partial correction of the anemia with recombinant human erythropoietin treatment

The purpose of this work was to study the effects of correcting anemia on the distribution and partition of body fluids in dialyzed uremic subjects. We studied nine (7 m, 2 f) patients before and three months after the start of i.v. treatment with rHu-EPO, measuring total body water (TBW) with 3H2O, extracellular fluid volume (ECFV) with 35SO4 and plasma volume (PV) with 125I-SA. The intracellular water (ICW) and the interstitial fluid volumes (IFV) were derived by calculation from those measurements. The total blood volume (TBV) was calculated from the PV and the packed cell volume (PCV). Mean TBW, 482 +/- 45 (M +/- SD) ml/kg/bw and ECFV, 168 +/- 27.5 ml were significantly lower in patients than in nine matched normal controls, while the mean ICW (315 +/- 43 ml/kg) was similar. PCV before the start of rHu-EPO was 17.2 +/- 2.9% and had risen significantly to 31.3 +/- 4.8% (p = 0.000) after three months of therapy. Body weight (58 +/- 13 kg), TBW, ECFV and ICW did not change. TBV before rHU-EPO was 68.7 +/- 7.5 ml/kg and remained nearly unchanged, while PV fell significantly from 57 +/- 9 to 48 +/- 8 ml/kg (p < 0.025), with the calculated IFV rising from 111 +/- 25 to 127 +/- 27 (p = 0.000). The PV/IFV ratio decreased from 0.53 +/- 0.12 to 0.38 +/- 0.09 (p = 0.001). The decrease in PV/IFV ratio was paralleled by simultaneous increase in PCV in all but one patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of chronic treatment with phenazone on the hot-plate test and [3H]serotonin binding sites in pons and cortex membranes of the rat

Many reports indicate that nonsteroidal anti-inflammatory drugs exert their antinociceptive effect through adrenergic and serotoninergic systems. We investigated the acute and chronic effects of phenazone on the pain threshold and on brain serotonin binding sites. A relationship between phenazone serum levels and the antinociceptive effect was found; acute treatment with phenazone provokes a significant decrease in serotonin binding sites both in the pons and cerebral cortex after 2, 4 and 8 h, but not after 24 h. After 15 and 30 days of treatment, the number of binding sites increases both in the pons and cortex.

No modifications of GABAA and benzodiazepine receptors following experimental dysthyroidism in rats

The effect of a treatment with L-triiodothyronine (T3) or propylthiouracil (PTU) on the characteristics of benzodiazepine and chloride ion channel binding sites in rat hippocampus and cerebral cortex was studied using a radiolabelled technique. In our experimental conditions, neither hyper- nor hypothyroidism modified number and affinity of [3H]flunitrazepam or [3H]butylbicycloorthobenzoate (TBOB) binding sites. These data indicate that neither benzodiazepine nor chloride ionophore sites of the GABA complex are modified in an experimental condition of dysthyroidism.

Repeated administration of triiodothyronine enhances the susceptibility of rats to isoniazid- and picrotoxin-induced seizures

In an experimental condition of hyperthyroidism, obtained by repeated administration of triiodothyronine in adult rats (100 micrograms/kg/day, sc for 7 consecutive days), there is an increased susceptibility to the convulsant effect of isoniazid (300 mg/kg, ip) and picrotoxin (4 mg/kg, ip). On the other hand, the characteristics of brain [3H] flunitrazepam binding sites are not modified. These data afford further experimental evidence of the influence of thyroid hormones on brain function.

Improvement in exercise capacity after correction of anemia in patients with end-stage renal failure

Changes in exercise tolerance occurring after correction of anemia with recombinant human erythropoietin in a group of patients with end-stage renal failure were evaluated. Ten patients, aged 29 +/- 11 years, on chronic hemodialysis treatment, with no associated diseases, were evaluated by cardiopulmonary bicycle exercise testing and M-mode, 2-dimensional and pulsed doppler echocardiography before and after anemia correction. After 1 and 3 months of therapy, hemoglobin plasma levels increased from 5.9 +/- 1.2 to 7.7 +/- 1.3 and 9.9 +/- 1.4 g/dl, with a concomitant increase in peak oxygen consumption (VO2) from 21.4 +/- 4.3 to 24.4 +/- 4.3 and 26.6 +/- 4.6 ml/kg/min and of VO2 at the ventilatory threshold from 15.0 +/- 3.7 to 17.3 +/- 3.7 and 16.8 +/- 3.4 ml/kg/min. After 3 months of therapy, systolic blood pressure significantly decreased both at peak exercise (159 +/- 35 to 134 +/- 22 mm Hg) and ventilatory threshold (140 +/- 27 to 123 +/- 19 mm Hg), whereas cardiac index at rest decreased from 3.3 +/- 0.7 to 2.8 +/- 0.5 liters/min/m2 and heart rate from 77 +/- 12 to 70 +/- 10 beats/min. However, no significant relation was found between hemoglobin plasma levels and peak VO2, whereas a significant relation was found between hemoglobin concentration and cardiac index at rest.

Reversal of left ventricular hypertrophy following recombinant human erythropoietin treatment of anaemic dialysed uraemic patients

To clarify the role of chronic anaemia in the pathogenesis of the left ventricular hypertrophy (LVH) of chronic uraemia, nine normotensive dialysed patients were studied before and 3 and 6 months after start of intravenous treatment with recombinant human erythropoietin (rHuEpo). M-Mode echocardiographic estimations of left ventricular mass indices (LVMi) and plasma noradrenaline determinations were made at 3 and 6 months, and total blood volume (TBV) only at 6 months. Resting haemoglobin values were 5.9 +/- 1.3 (SD) g/dl, increased within 3 months to 10.2 +/- 1.2 (P less than 0.001), then remained unchanged. Baseline LVMi was 115 +/- 18 g/m2 body surface area (b.s.a.) and decreased significantly (P less than 0.0025) over the entire period to a final value of 78 +/- 13 g, which did not differ from the average value for 19 healthy controls. Resting plasma noradrenaline was 1.45 +/- 0.44 pmol/ml and did not change significantly, although values were reduced at the 3rd month, when decreased heart rates and slightly and non-significantly increased blood pressures were recorded. TBV did not vary because the increased erythrocyte mass was compensated for by parallel decreases in plasma volume. These data demonstrate the existence of a cause-effect relationship between uraemic anaemia and LVH, although the precise mechanism remains unknown. Amelioration of anaemia with rHuEpo, by allowing recovery from the attendant LVH, might improve long-term cardiovascular prognosis in some dialysed uraemic patients.

Influence of the selective cholecystokinin antagonist L-364,718 on pain threshold and morphine analgesia

The intracerebroventricular injection of the cholecystokinin-A receptor antagonist L-364,718, at the doses of 0.5, 5, 10 or 20 micrograms/mouse, while having no effect on pain threshold (hot plate, 51 degrees C), antagonized the analgesic activity of morphine (10 mg/kg i.p.). This effect was obtained with a dose of 10 micrograms/mouse and was associated with a reduction of brainstem opiate-binding sites.

Effects of thyroid status on the characteristics of alpha 1-, alpha 2-, beta, imipramine and GABA receptors in the rat brain

The effects of a chronic treatment with L-triiodothyronine (T3; 100 mg/rat/day s.c. for 7 days) or with propylthiouracil (PTU; 50 mg/rat/day for 35 days by stomach tube) on the characteristics of alpha 1, alpha 2, beta, imipramine and GABA binding sites in different brain areas of the adult rat have been studied. T3-treatment caused an increase in the number of [3H]dihydroalprenolol and a decrease in the number of [3H]muscimol binding sites in the cerebral cortex. PTU-treatment caused a decrease in the number of [3H]prazosin, [3H]yohimbine and [3H]dihydroalprenolol binding sites in the cerebral cortex, while the number of [3H]imipramine binding sites was reduced in the cerebral cortex and hypothalamus, and increased in the hippocampus. Affinity constants were never modified. Concurrent experiments showed that the "in vitro" addition of T3 and PTU did not influence the binding of any of the ligands employed to control rat brain membranes. The present data further support the view that neurotransmission in the CNS is influenced by the thyroid status.

Renormalization of high cardiac output and of left ventricular size following long-term recombinant human erythropoietin treatment of anemic dialyzed uremic patients

To obtain information on the effects of the correction of uremic anemia on cardiac function and size, nine normotensive dialyzed patients were studied before, during and six months after the start of i.v. treatment with recombinant human erythropoietin (rHuEPO). Pulsed-doppler echocardiographic determinations of the cardiac index (CI) and M-Mode echocardiographic estimations of the indexed left ventricular end diastolic diameter (LVEDDi), interventricular septum (IVSi), left ventricular posterior wall (LVPWi), with calculations of the left ventricular mass index (LVMi), were made on every occasion. Mean (+/- SD) hemoglobin (Hb) concentration before rHuEPO was 5.9 +/- 1.3 g/dl and rose significantly (p less than 0.0001) up to the third month, then remained constant. Baseline CI (3.4 +/- 0.6 l/min/m2bsa) was significantly higher (p less than 0.0001) than in healthy subjects (2.5 +/- 0.5 l), and decreased after the third month to a value (2.8 +/- 0.5 l) no longer different from that of controls. From pooled baseline and third month data, an inverse relationship between Hb and CI was found (p less than 0.0001). Baseline LVEDDi (32.7 +/- 4.3 mm/m2bsa), IVSi (6 +/- 1.1 mm/m2bsa) and LVPWi (5 +/- 0.8 mm/m2bsa) were all significantly higher than in controls. After three months of therapy, the only change was a decrease in LVPWi while after six months all indices, including the LVMi, decreased to values no longer higher than in controls. From pooled baseline and six months data, an inverse relationship between Hb and LVMi was found (p less than 0.0001). We conclude that treatment of uremic patients by rHuEPO is able to renormalize their already increased cardiac output soon after correction of the anemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of gonadotropin-releasing hormone on castration-induced 'depression' in mice: a behavioral and binding study

Long-term (33-35 days) castration caused a significant increase in the duration of immobility of male and female mice in the tail suspension test (an animal model of depression), and a significant decrease in the maximum number (Bmax) of [3H]imipramine binding sites in the cerebral cortex of male mice. In the tail suspension test, gonadotropin-releasing hormone (GnRH), s.c. injected 3 times at 3-h intervals at doses of 0.2, 2 or 20 micrograms/kg, did not significantly modify the duration of immobility of castrated animals and did not reduce that of sham-operated ones, while desipramine (20 mg/kg s.c. 1 h before testing) restored immobility to normal in castrated animals and reduced it significantly in sham-operated ones. The same treatment schedule with GnRH produced an increase in the number of [3H]imipramine Bmax in cortical membranes that was statistically significant at the dose of 2 micrograms/kg. It is concluded that the castration-induced depression-like behavior in mice seems not to be due to the decreased levels and release of GnRH, and that GnRH has no antidepressant-like effect in mice, at least at our dose levels; however, GnRH seems to increase the number of cortical [3H]imipramine binding sites.

[3H]imipramine binding in discrete brain areas is affected by castration in male rats

In adult male rats, castration induces a progressive decrease in the number of [3H]imipramine binding sites in the cerebral cortex and hypothalamus, and a progressive increase in the hippocampus. Testosterone completely prevents this effect of castration, but has no effect on the characteristics of brain imipramine binding sites in intact, non-castrated animals. These data suggest that threshold levels of testosterone are necessary for the maintenance of a normal number of imipramine binding sites in the rat brain, but that these binding sites are not modified by excess testosterone.