Acetaminophen blocks spinal hyperalgesia induced by NMDA and substance P

The hypothesis tested was that inhibition of the L-arginine-nitric oxide (NO) pathway may represent a potential central mechanism of action for acetaminophen (paracetamol). Spinal administration of N-methyl-D-aspartate (NMDA, 0.5 nmol), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA, 0.1 nmol) or substance P (SP, 0.5 nmol) to the rat provoked a specific behaviour characterized by biting, scratching and licking (BSL). This behaviour was antagonized by pretreatment with acetaminophen for NMDA and SP but not for AMPA. Further, the antinociceptive effect of acetaminophen was readily reversed by administration of the natural substrate for nitric oxide synthase (NOS), L-arginine, but not by D-arginine. This suggests that the analgesic effect of acetaminophen is related to inhibition of NO generation. Potential mechanisms for this may involve NMDA and SP. Our data suggest that a significant portion of the analgesic effect of acetaminophen, when used clinically, may be related to an interaction with the central nervous system L-arginine-NO pathway.

Vasopressin alters female sexual behaviour by acting on the brain independently of alterations in blood pressure

Subcutaneous (s.c.) administration of Arg-vasopressin (AVP) prolongs retention of a learned behaviour and elevates arterial blood pressure. Intracerebroventricular (i.c.v.) injection of a thousandfold lower dose of AVP than needed with s.c. injection produces the same behavioural effect, suggesting that AVP acts on the brain to control behaviour. However, as i.c.v. injection of AVP also elevates arterial blood pressure, it was suggested that AVP, and perhaps other peptides as well, influences behaviour indirectly by eliciting a peripheral response, for example blood pressure changes, rather than by acting directly on the brain. The suprachiasmatic nuclei (SCN) of the hypothalamus, a source of vasopressin production, inhibit sexual receptivity in oestradiol-17 beta-treated ovariectomized rats during the light phase of the daily lighting cycle, leading to speculation that vasopressin might inhibit sexual behaviour. Here we report that i.c.v. injections of AVP (1, 4 or 10 ng) inhibit sexual behaviour in receptive rats. This behavioural response is prevented by i.c.v. injection of an antiserum to AVP 30 min before AVP injection. Subcutaneous injection of a high dose of AVP (1 microgram) has no behavioural effect but elevates arterial blood pressure within 30 min of administration. Intracerebroventricular injection of a behaviourally effective dose of AVP (1 ng) has no effect on blood pressure. The results provide direct evidence that AVP can alter behaviour by an action on the brain and independently of its effect on blood pressure.

Role of microcystins in poisoning and food ingestion inhibition of Daphnia galeata caused by the cyanobacterium Microcystis aeruginosa

The effects of microcystins on Daphnia galeata, a typical filter-feeding grazer in eutrophic lakes, were investigated. To do this, the microcystin-producing wild-type strain Microcystis aeruginosa PCC7806 was compared with a mcy- PCC7806 mutant, which could not synthesize any variant of microcystin due to mutation of a microcystin synthetase gene. The wild-type strain was found to be poisonous to D. galeata, whereas the mcy- mutant did not have any lethal effect on the animals. Both variants of PCC7806 were able to reduce the Daphnia ingestion rate. Our results suggest that microcystins are the most likely cause of the daphnid poisoning observed when wild-type strain PCC7806 is fed to the animals, but these toxins are not responsible for inhibition of the ingestion process.

Central hypotensive effect of alpha-methyldopa

In cats under chloralose anaesthesia l-α-methyldopa (20 mg/kg) was infused for 1 hr into the left vertebral artery. One to 3 hr after the end of the infusion a gradual and significant lowering of mean arterial blood pressure was observed. The dopamine and noradrenaline contents of the brain were significantly reduced while brain 5-hydroxytryptamine and heart noradrenaline concentrations remained normal. The same low dose of l-α-methyldopa infused into a systemic vein did not affect the blood pressure. However, brain dopamine and noradrenaline were depleted to the same extent as observed after infusion into the vertebral artery. Intravenous infusion of a large dose of l-α-methyldopa (200 mg/kg) did not significantly alter mean arterial blood pressure but lowered brain dopamine, noradrenaline and 5-hydroxytryptamine levels. No effect on heart noradrenaline was observed. Infusion of saline or the d-isomer of α-methyldopa (20 mg/kg) into the vertebral artery had no effect on blood pressure or tissue monoamines.

A prospective study of impairment of cognition and memory and recovery after subarachnoid hemorrhage

In this prospective study, a series of 89 patients with subarachnoid hemorrhage (SAH), most of whom had a "good" neurological outcome, were assessed with a range of tests of memory and cognition as inpatients and at 10 weeks and 12 months after SAH. On tests of verbal cognition and memory, most patients had scores in the normal range 12 months after SAH. However, a significant number of patients still showed impairment on tests of visuospatial construction and memory, mental flexibility, and psychomotor speed at the 12-month assessment. Statistical analyses were carried out for each test score to see whether aneurysm site, location of blood on the admission computed tomographic scan, vasospasm, ischemia, hydrocephalus, grades at admission to and at discharge from hospital, and Glasgow Outcome Scale score at follow-up were associated with test scores. Aneurysm site was not shown to be associated with performance on any test at any time, and the other complications of SAH had only minimal predictive value. The grade at discharge proved to be the best predictor of impairment of cognition and memory at both follow-up assessments. Older subjects did not recover to the same extent as younger subjects by the 12-month assessment. The authors conclude that the diffuse effects of SAH are more important than focal neuropathology in relation to cognitive impairment in this group of patients.

Evidence that the hypotensive action of methyldopa is mediated by central actions of methylnoradrenaline

Mean arterial blood pressure was recorded in conscious normotensive rats through indwelling arterial catheters. The effect of l-α-methyldopa (α-MD) (400 mg/kg, i.p.) was studied in animals pretreated with α-methyl-m-tyrosine (400 mg/kg i.p.) 27 and 15 h before α-MD, α-methyl-p-tyrosine methylester (H 44/68) (250 mg/kg, i.p.) 1 h before α-MD, and dl-α-hydrazino-α-methyl-β-(3,4-dihydroxyphenyl) propionic acid (MK 485, 100 mg/kg, i.p.) 30 min before α-MD. This pretreatment, which resulted in a severe depletion of endogenous catecholamines, did not alter the hypotensive effect of α-MD. The effect of α-MD (200 mg/kg, i.p.) was studied 30 min after pretreatment with the dopamine β-hydroxylase inhibitor, bis (4-methyl-l-homopiperazinyl-thiocarbonyl) disulphide (FLA-63) (25 mg/kg, i.p.). The hypotensive response to α-MD was completely abolished in these experiments. The formation of α-methylnoradrenaline from α-MD was prevented after FLA-63 but there was a significant increase in the amounts of α-methyldopamine formed.

Central hypotensive effect of L-3,4-dihydroxyphenylalanine in the rat

Mean arterial blood pressure was recorded through in-dwelling arterial catheters in conscious normotensive Sprague-Dawley rats. L-3,4-Dihydroxyphenylalanine (L-dopa) was given in various doses intraperitoneally, alone and after pretreatment with an inhibitor of dopa decarboxylase, α-hydrazino-α-methyl-β-(3,4-dihydroxyphenyl) propionic acid (MK 485) or seryl-2,3,4-trihydroxybenzylhydrazine (Ro 4–4602). L-Dopa (50 mg/kg) produced a hypertensive response which was abolished by MK 485 (100 mg/kg). A larger dose of L-dopa (200 mg/kg) after MK 485 caused a significant lowering of blood pressure after 15–20 min. After Ro 4–4602 (400 + 200 mg/kg), injection of L-dopa (200 mg/kg) had no significant effect on blood pressure. The hypotensive response to L-dopa (200 mg/kg) after MK 485 was not influenced by the central dopamine receptor blocking agent, spiroperidol (0.1 mg/kg), but could be completely inhibited by the dopamine β-hydroxylase inhibitor, bis-(4-methyl-1-homopiperazinyl-thiocarbonyl)disulphide (FLA 63) (40 mg/kg). Pretreatment with protripty-line (10 mg/kg) completely blocked the hypotensive effect of L-dopa after MK 485. In correlative biochemical experiments, levels of noradrenaline and dopamine were determined in brain, heart and femoral muscle. L-Dopa (200 mg/kg) alone caused a significant increase of dopamine levels in all tissues. After MK 485 and Ro 4–4602 L-dopa did not significantly increase the levels of dopamine in heart or femoral muscle; however, brain dopamine levels were increased more than after L-dopa alone, but brain dopamine levels after Ro 4–4602 were significantly lower than after MK 485, indicating some central decarboxylase inhibition by Ro 4–4602. L-Dopa alone reduced the noradrenaline content of the heart and this effect was prevented by MK 485 and Ro 4–4602. The results show that decarboxylation of L-dopa in both the central and the peripheral nervous system leads to an increase in blood pressure. Decarboxylation of L-dopa in the central nervous system only results in a hypotensive response, provided that high amounts of dopamine are formed in the brain. This effect was prevented by an inhibitor of dopamine β-hydroxylase but not by a dopamine receptor blocker. Therefore, a central noradrenaline mechanism seems to be involved. The presence of an intact membrane pump in noradrenaline neurons may be essential since protriptyline also blocked the hypotensive action.

A placebo-controlled crossover trial of creatine in mitochondrial diseases

To test the efficacy and safety of creatine (Cr) monohydrate in mitochondrial diseases, 16 patients with chronic progressive external ophthalmoplegia or mitochondrial myopathy were randomized in a crossover design to receive double-blind placebo or 20 g Cr/day for 4 weeks. Cr was well tolerated, but there were no significant effects with regard to exercise performance, eye movements, or activities of daily life. The power of this pilot study was limited and future multicenter trials are needed.

Central, naloxone-reversible antinociception by diclofenac in the rat

The antinociceptive effect of subcutaneously (s.c.), intracerebroventricularly (i.c.v.) or intrathecally (i.t.) administered diclofenac was studied in a series of experiments employing the tail-flick (0.01-10.0 mg/kg body weight i.p., 1-50 micrograms i.c.v., 1-10 micrograms i.t.) and hot-plate (0.01-50 mg/kg body weight i.p., 1-50 micrograms i.c.v., 1-10 micrograms i.t.) models representing somatosensory stimuli and the writhing test (0.001 mg-10 mg s.c., 0.1-200 micrograms i.c.v., 0.1-100 micrograms i.t.) and colorectal distension (1-200 micrograms i.c.v.) models representing noxious visceral stimuli. Diclofenac did not exert any antinociceptive effects in the tail-flick or hot-plate models. In the writhing test, diclofenac dose-dependently inhibited the number of writhings after s.c. administration (0.001-10.0 mg/kg body weight) with an ED50 of 1 mg/kg. A similar dose-dependent action of diclofenac was seen after i.c.v. (0.1-200 micrograms) and i.t. (0.1-100 micrograms) administration with an ED50 of 3 micrograms in both cases. The antinociceptive effect of diclofenac administered s.c., i.c.v. or i.t. was almost completely reversed by pretreatment with naloxone, (1 mg/kg body weight s.c.). In the colorectal distension model, the i.c.v. administration of diclofenac (1-200 micrograms), which attenuated the cardiovascular response to colorectal distension, was reversed by naloxone. The pressor and tachycardia response to a 20 s, 80 mmHg colorectal distension was inhibited by diclofenac 100 micrograms i.c.v. (16.1 +/- 1.7 mmHg or 58% and 39.4 +/- 0.4 bpm or 70% versus control, respectively). It is concluded that diclofenac exerts a central, naloxone-reversible antinociceptive action in experimental animals after noxious visceral stimuli but not after somatosensory stimuli.

Effects of on-farm diets for organic pig production on performance and carcass quality

An experiment was conducted to evaluate the effects of a restriction to home-grown feedstuffs and abstinence from supplementation with synthetic amino acids (AA), as ideal objectives in organic pig production according to the IFOAM standards, on growth performance and carcass characteristics. One hundred individually housed pigs were allocated to four dietary treatments and fed from growing through finishing to compare three organic barley/wheat-based diets with an isocaloric conventional diet supplemented with synthetic AA. Protein sources in the organic treatments were either faba beans, supplemented with potato protein to the same AA level as the control diet, peas and lupines, or faba beans and lupines, both without further supplementation, leading to a lower level of limited AA. Supplementation of organic diets with potato protein resulted in the same performance as supplementing the conventional diet with synthetic AA, although crude protein levels differed markedly. Pigs fed the organic diets without AA supplementation grew more slowly (P < .05) and had a decreased feed intake in the grower period (P < .05) but nearly the same feed efficiency (P > .05) as pigs fed conventional or organic diets with AA supplementation. Carcass characteristics differed in percentage of lean meat and longissimus area, being lower in the treatments without AA supplementation (P < .05). However, the intramuscular fat was higher without AA supplementation (2.9% fat) than with supplementation (1.2% fat) (P < .01). The data show that the exclusion of AA supplementation resulted in a reduction in pig performance but in an increase in intramuscular fat content; the latter is an important aspect of eating quality characteristics.

Cardiovascular effects in the rat of ketanserin, a novel 5-hydroxytryptamine receptor blocking agent

Following intravenous administration of ketanserin (0.3-10 mg kg-1) to conscious or anaesthetized normotensive and spontaneously hypertensive rats there were dose-dependent blood pressure reductions but no compensatory tachycardia. Intracerebroventricular administration of ketanserin (25-500 microgram) had inconsistent and largely insignificant cardiovascular effects. In a dose range where it produces hypotension ketanserin antagonized the pressor responses to adrenaline and noradrenaline as well as to 5-hydroxytryptamine in monoamine depleted and spinalized rats. It is suggested that the hypotensive action of ketanserin in the rat does not involve a central mechanism but a peripheral alpha-adrenolytic action is implicated.

Localization of the central antinociceptive effects of diclofenac in the rat

The ethacrynic acid-induced writhing response (WR) in the rat was studied after microinjections of diclofenac 0.1 ng-1 microgram/0.5 microliter (0.32 pmol to 3.2 nmol) into several brain regions involved in control of nociceptive behavior. The WR was inhibited after injections into the periaqueductal grey matter (PAG), ventromedial thalamus (VM), medial preoptic area (MPA) and the nucleus raphe magnus (NRM). Morphine 50 ng/0.5 microliter (0.16 nmol) was used as a positive control and vehicle injections were performed as negative reference. After diclofenac, there was a dose-dependent reduction of the WR with a threshold dose of approximately 1-10 ng in all brain areas studied except the nucleus reticularis paragigantocellularis interna (NRPGi). Naloxone 50 ng/0.5 microliter (0.15 nmol) administered into the same site 30 min after diclofenac injection, antagonized the diclofenac-induced inhibition of the WR almost completely in PAG and VM. Previous results demonstrate a central, naloxone-reversible component in the analgetic action of diclofenac. A qualitatively similar, centrally induced inhibition of the WR may be elicited after injections into PAG, VM and NRM. Thus, in addition to its peripheral mechanism of action, the non-steroidal anti-inflammatory drug, diclofenac, has a central mechanism of action which directly or indirectly involves a central opioid component.

Central cardiovascular and biochemical effects of baclofen in the conscious rat

Baclofen (beta-D-chlorophenyl-GABA, 1.25-10 mg kg-1 i.p.) elicited dose-dependent increases in blood pressure and heart rate in conscious rats. similar responses were observed after intracisternal or intracerebroventricular injections of baclofen 0.125-1 microgram kg-1. Baclofen i.p. was largely ineffective after spinal transection at C7. Pretreatment with phenoxybenzamine, bethanidine or hexamethonium antagonized the cardiovascular effects of i.p. baclofen. These actions were significantly attenuated after catecholamine depletion and synthesis inhibition by means of alpha-methyl-m-tyrosine and alpha-methyl-p-tyrosine. The responses to baclofen were not affected by bilateral adrenal demedullation but abolished by pentobarbitone anaesthesia. Hence, the cardiovascular effects of baclofen are probably evoked from central nervous structures and mediated via the sympathetic nervous system. In doses corresponding to those used in the circulatory studies i.p. baclofen increaed endogenous concentrations of brain DA and decreased DA utilization but only slightly affected brain NA concentrations and utilization.

Antihypertensive effects of chronic 5-hydroxytryptamine (5-HT2) receptor blockade with ketanserin in the spontaneously hypertensive rat

The effects of chronic oral treatment with the 5-hydroxytryptamine (serotonin) receptor blocking agent ketanserin (17 mg/100 g dry food) on blood pressure, heart weight, peripheral vascular reactivity, baroreceptor sensitivity, central cardiovascular reactivity and central catecholamine turnover were investigated in the spontaneously hypertensive rat. Blood pressure measurements were performed in conscious rats 24 h after insertion of catheters. After 6 weeks treatment basal blood pressure was reduced (16%) compared to control rats (given identical food, except for ketanserin). Both heart weight and body weight were reduced (both to 93% of control values) leaving heart weight/body weight ratio unchanged. Pressor responses to phenylephrine and depressor responses to isoprenaline (after pretreatment with reserpine and atropin) were not different while the blood pressure increase to 5-hydroxytryptamine was inhibited, indicating that after 6 weeks treatment the blood pressure reduction is not directly related to alpha-adrenoceptor blockade. Cardiovascular response to stress (jet air), baroreceptor sensitivity (bradycardia to phenylephrine) and central catecholamine synthesis rates (accumulation of 5-hydroxytryptophan and dihydroxyphenylalanine after synthesis inhibition) were unchanged supporting earlier evidence that central mechanisms probably do not contribute to the hypotensive effects of ketanserin.

[Epidemiology and clinical aspects of cold urticaria]

To study the frequency and clinical aspects of cold urticaria in Central Europe, patient data from a university dermatology clinic and a private dermatology office between 1984-94 were analysed and the patients re-examined if possible. The incidence of cold urticaria was found to be 0.05%. Of the 56 patients with cold urticaria (31 women, 25 men), 49 had idiopathic cold urticaria. The mean age was 41.0 +/- 15.6 year, the mean duration of disease 7.9 +/- 5.8 years. Atopy was found in 46.5% of patients, and 23.2% of the patients suffered from other types of urticaria (cholinergic, chronic idiopathic, dermographic, aquagenic and heat-induced). Laboratory examinations were only rarely abnormal. 44 patients were treated with antihistamines, with generally only moderate symptomatic improvement. Treatment with antibiotics (penicillin, 1-2 mil IU/d over 2-4 weeks, n = 18, or tetracyclines, 2 g/d over 2 weeks, n = 10) induced full remission in 13 patients and symptomatic improvement in 8. During an average of 6.5 year-follow-up, 20 of 43 symptomatic patients went into spontaneous remission. The good therapeutic response to antibiotics in this study underlines the need for a better elucidation of the cause of cold urticaria, in view of possible infectious causes.

On the localization of the hypotensive effect of L-dopa

Mean arterial blood pressure was recorded in anaesthetized rats before and after a mid-collicular transection of the brain (decerebration). Basal blood pressure was not changed by the decerebration. Injection of l-dopa (200 mg/kg, i.p.) after peripheral dopa decarboxylase inhibition by l-α-hydrazino-α-methyl-β-(3,4-dihydroxyphenyl) propionic acid (MK 486, 100 mg/kg, i.p.) resulted in a significant reduction of arterial pressure to the same level in both control (sham- operated) and decerebrated rats after 30 min. In other experiments, anaesthetized rats were spinalized at C7-Th1. Basal blood pressure became significantly lower than in control and decerebrated rats and l-dopa after MK 486 in the same doses did not affect blood pressure. Biochemical determinations of noradrenaline and dopamine showed that administration of l-dopa after MK 486 to decerebrated rats in the same doses as in the blood pressure experiments resulted in a pronounced increase of dopamine in both parts of the brain.

Effect of GABA analogues on blood pressure and central GABA metabolism in the rat

Gamma aminobutyric acid (GABA) and different GABA analogues were examined for their cardiovascular actions and their influence on striatal dopamine (DA) levels and GABA accumulation after aminooxyacetic acid (AOAA). Gamma hydroxybutyric acid (GHBA) and baclofen caused hypertension and tachycardia after systemic as well as intracerebroventricular administration, while the opposite was true for GABA and muscimol. The hypertension after GHBA and baclofen was not reduced by picrotoxin or bicuculline and was not influenced by varying GABA levels by 3-mercaptopropionic acid (3-MPA) or AOAA. GHBA and muscimol but not baclofen reduced GABA accumulation induced by AOAA. Picrotoxin in a subconvulsive dose increased GABA accumulation and antagonized the inhibition after GHBA or muscimol. Bicuculline and a moderate dose of picrotoxin tended to decrease GABA accumulation by themselves and if anything augmented the effects of GHBA and muscimol. GHBA and baclofen but not muscimol in combination with AOAA increased DA levels, which was not prevented by picrotoxin or bicuculline. We conclude that the cardiovascular actions of GHBA and baclofen are probably not mediated by mechanisms identical to those of muscimol or exogenous GABA. In view of the biochemical results their actions would however be compatible with a concept of different GABA receptors.

Steroid 11ß-hydroxylation by a fungal microsomal cytochrome P450

The steroid 11ß-hydroxylase activity of the fungus Cochliobolus lunatus was increased about 100-fold by cultivation of mycelia for 4-5 h with 20-hydroxymethyl-1,4-pregnadien-3-one. Cell-free extracts revealed a maximum activity of 45 nmol 11ß-hydroxyprogesterone/h·mg protein in the 100,000 g pellet fraction. The 11ß-hydroxylation was dependent on NADPH. The formation of 11ß-hydroxyprogesterone correlated linearly with the cytochrome P450 concentration. The fungal 11ß-hydroxylase transformed both 21-methyl and 21-hydroxymethyl steroids. The enzyme showed a broader substrate specificity and lower regioselectivity as compared with the adrenal cytochrome P45011ß system. The fungal cytochrome P450 was partially purified to a specific content of 700 pmol P450/mg protein. Western blots showed that polyclonal antibodies against cytochrome P45011α from Rhizopus nigricans cross-react with a 60 kD protein of partially purified fractions. The NADPH-cytochrome c reductase was enriched up to a specific activity of 20 U/mg protein. Polyclonal antibodies against NADPH-cytochrome P450 reductases from Candida maltosa and rat liver cross-reacted with the fungal reductase. It is concluded that the 11ß-hydroxylase of Cochliobolus lunatus represents a microsomal two-component monooxygenase system which is composed of a cytochrome P450 (M(r) 60 kD) and a NADPH-cytochrome P450 reductase (M(r) 79 kD).

On the disulfiram-like effect of coprine, the pharmacologically active principle of Coprinus atramentarius

Coprine or disulfiram was given to rats in various doses at various time intervals before the administration of 2 g/kg ethanol. The ratio acetaldehyde/ethanol in the alveolar air was measured by gas chromatography and was taken as an index of the aldehyde dehydrogenase (ALDH) activity. The activity of dopamine beta-hydroxylase (DBH) was estimated in the same animals by measuring the amount of 14C-octopamine formed from 14C-tyramine in the heart. Coprine and disulfiram both caused an increase in the acetylaldehyde/ethanol ratio, coprine being more potent than disulfiram. Disulfiram, but not coprine, reduced the net yield of 14C-octopamine. In rats pretreated with either coprine or disulfiram, blood-pressure and heart-rate were recorded before and after intraperitoneal injections of 0.4 g/kg ethanol. In both cases ethanol caused a marked and rapid fall in blood-pressure. However, this effect was accompanied by tachycardia only in animals treated with coprine. It is concluded that coprine like disulfiram inhibits ALDH, but only disulfiram causes an additional inhibition of DBH. This difference may account for differences in the cardiovascular response to ethanol.