Cefazolin: a valid model of experimental epilepsy?

In various animal species (chicks, rats and rabbits) the intravenous injection of high doses of cefazolin, a cephalosporin not hitherto reported to produce epileptic seizures, was found to produce epileptiform electrocortrical changes similar to those evoked by intravenous benzylpenicillin. Similar phenomena as those reported after systemic injection were also observed after microinjection of cefazolin into the III cerebral ventricle. In fact, both in chicks and rats cefazolin given by the latter route produced wild running crisis, myoclonic jerks of the limbs and in some instances generalized clonic convulsions. Concomitantly, bilateral electrocortical high voltage bursts of spikes were observed, followed during the intercritic period by periodic bilateral or unilateral single spikes.

Pharmacokinetics and efficacy of teicoplanin against intramammary infections in sheep

The pharmacokinetics of teicoplanin were evaluated in 10 healthy sheep. After intravenous injection it showed monophasic behaviour, with a short mean (sd) elimination half-life (5 [0.24] hours). After intramuscular injection its bioavailability was 100 per cent but it was absorbed slowly; its elimination half-life was satisfactorily slow (9.23 [0.74] hours). Its efficacy was evaluated in 26 crossbreed sheep with milk positive to strains of Staphylococcus aureus, coagulase-negative staphylococci and Streptococcus agalactiae, and clinical signs of disease. In 19 of them a single intramuscular dose of 6 mg/kg bodyweight resulted in a complete resolution of the clinical signs, and no microorganisms were detected in milk by the fifth day; in the other seven sheep, with more severe intramammary infections, three consecutive daily intramuscular doses of 6 mg/kg bodyweight were necessary. There were no local or systemic side effects and no relapses during 30 days after the treatments in any of the sheep.

Levels and congener pattern of polychlorinated biphenyl and organochlorine pesticide residues in bluefin tuna (Thunnus thynnus) from the Straits of Messina (Sicily, Italy)

The aim of this study is to assess the accumulation of OCs and PCBs in Thunnus thynnus and to elucidate the suitability of this species as a bioindicator for monitoring contaminations of these compounds in the marine ecosystems of the Straits of Messina. This investigation was conducted on fat, liver and muscle samples of 14 T. thynnus collected during April 2004. Quantitative determination of OCs and PCBs in the various samples examined has been carried out using GC-ECD and GC-MS. The results obtained show the presence of low concentrations of p,p'-DDE and PCB congeners (138, 153 and 180) in all fat, liver and muscle samples caught in the Straits of Messina. Concentrations of p,p'-DDE and PCB congeners (138, 153 and 180) in all the samples examined were below MRLs (CE n. 97/41, 1999/65 and 1999/71).

Effects of clenbuterol on haemocoagulation process in calves

The aim of this investigation was to study the effects of clenbuterol treatment (1 mug/kg b.w. i.m. for 10 consecutive days) on haemocoagulation process in seven calves. From each animal, blood samples were taken before (basal sample) and 24, 72, 144, 216, 264, 336 and 360 h after the end of treatment and some parameters were evaluated: coagulation process [prothrombin (PTT) and thrombin times (PT)], a complete blood count and plasmatic levels of 3'5'-monophosphatocyclic-adenosine (c-AMP) . A comparison of the values in each time group during the whole course of the experiments shows a significant increase (P < 0.03, P < 0.01) in PT and PTT at 72, 144, 216 and 264 h. Significant increase (P < 0.01) in c-AMP plasma levels were observed at 144, 216 and 264 h. All these values returned to normal levels after 360 h.

Organochlorine compounds and heavy metals in the soft tissue of the mussel Mytilus galloprovincialis collected from Lake Faro (Sicily, Italy)

Three hundred samples of Mytilus galloprovincialis were collected from five stations (north, south, east, west and centre) of Lake Faro to evaluate the concentrations of organochlorine compounds and heavy metals. Quantitative determinations of organochlorine pesticides and PCBs were made by GC-ECD and confirmed with GC-MS. Concentrations of "essential" (Cu, Se and Zn) and "toxic" (As, Cd, Hg and Pb) metals were determined by an atomic absorption spectrophotometer. The results obtained show the low residue levels of p,p'-DDE in six samples of M. galloprovincialis from southern (7.00-11.00 ng/g w.w. and 148.3-275 ng/g l.w.) and western (7.60-15.37 ng/g w.w. and 126.7-256.2 ng/g l.w.) areas of Lake Faro. No appreciable residues of PCBs were found in any of the samples examined. Zn concentrations (range 11.0-18.5 microg/g w.w.) were higher than Cu (range 188.3-396.0 ng/g w.w.) and Se (range 93.5-288.9 ng/g w.w.) in all areas of origin. Cd (range 41.9-63.8 ng/g w.w.), Pb (range 64.8-93.0 ng/g w.w.) and Hg levels (range 5.7-13.1 ng/g w.w.) showed lower concentrations than permitted MRLs. The As levels were below detection limits for the all mussel samples. In conclusion, the absence of PCBs, the low levels of p,p'-DDE, the concentrations of Cd, Hg and Pb below permitted MRLs in M. galloprovincialis, used as a "biological indicator", show that Lake Faro is not at contamination risk from these contaminants and moreover is free from health problems for the consumer of mussel products.

Organochlorine pesticides and PCBs in wild boars from Calabria (Italy)

At present, there are no specific studies on the evaluation of environmental toxicological risks in Calabria (south of Italy) and on the presence of contaminants in the fauna of this region. The aim of the present research was to investigate the levels of contamination by OC pesticides and PCBs in some organs and tissues of wild boars (utilized as 'biological indicator') from various areas of Calabria. Quantitative determinations of organochlorines were carried out using GC-ECD and confirmed with GC-MS in 154 samples from wild boars (heart, liver, lung, kidney, muscle tissue and spleen) during the hunting season from 2000 to 2002. The results indicate the low residual levels of DDE in 8 samples and DDT in 4 samples and PCBs residues (Aroclor 1232) below the detection limits were found. Therefore, these results show that the Calabria region is not at contamination risk from organochlorines and moreover is free from health problems for the consumer of boar meat.

Levels of "toxic" and "essential" metals in samples of bovine milk from various dairy farms in Calabria, Italy

The aim of this research was to evaluate the possible contamination by heavy metals of milk from cows bred on various farms in Calabria. The concentrations of heavy metals were determined in 40 samples of bovine milk from the various dairy farms. Each sample, homogenized and powdered, was mineralized in a microwave oven. Quantitative analyses of Cd, Cr, Cu, Pb and Se were performed using an atomic absorption spectrophotometer with graphite furnace; As was analyzed by hot vapor generation technique and Zn with the flame method. As regards toxic heavy metals, highest values are those of As (g.m. 37.90 microg/kg w.w.) and Pb (g.m. 1.32 microg/kg w.w.), while lowest concentrations are those of Cd (g.m. 0.02 microg/kg w.w). With regard to essential metals, Zn (g.m. 2016 microg/kg w.w) and Se (g.m. 13.24 microg/kg w.w.) showed the highest concentrations, followed by Cr (g.m. 2.03 microg/kg w.w.) and Cu (g.m. 1.98 microg/kg w.w.). Further investigations of the levels of heavy metals (As) in a greater number of milk samples from various zones of Calabria are necessary, both to examine this problem from the clinical epidemiological point of view and to identify the possible causes of milk contamination.

Effects of monensin on Na+/K(+)-ATPase and Ca(++)-AtPase activities in chick skeletal muscle and myocardium after subacute treatment

Chicks were treated at 2 weeks of age with 4,15, 40, 100 and 150 mg/kg of monensin, an ionophore used for its anticoccidial and growth-promoting properties. In the present immunohistochemical study, the expressions and distribution of Na+/K(+)-ATPase and Ca(++)-ATPase were studied in myocardium and skeletal muscles (pectoral and quadriceps femoris). We detected an increase of Na+/K(+)-ATPase immunostaining with prominent staining of the sarcolemma and a slight increase of Ca(+)-ATPase with prominent staining of the sarcoplasma.

Effectiveness and kinetic behaviour of tilmicosin in the treatment of respiratory infections in sheep

Nineteen sheep which were anorexic, pyrexic, coughing, dyspnoeic and had a nasal discharge and symptomatic thoracic sounds on auscultation, received a single subcutaneous dose of 10 mg/kg bodyweight of tilmicosin. The clinical signs were eliminated within four to six days. The kinetic profiles of the drug after a single subcutaneous injection were compared in five healthy sheep and five infected sheep. More of the drug was absorbed by the infected animals and its concentration remained higher for significantly longer. The drug was well tolerated and no local or systemic side effects were observed.

Influence of D-cycloserine on the anticonvulsant activity of some antiepileptic drugs against audiogenic seizures in DBA/2 mice

D-Cycloserine (DCS; 1-100 mg/kg, intraperitoneally (i.p.)) was able to antagonise the audiogenic seizures in DBA/2 mice in a dose-dependent manner. DCS, 2.5 mg/kg i.p. did not significantly affect the occurrence of audiogenic seizures in DBA/2 mice, but potentiated the anticonvulsant activity of carbamazepine, diazepam, felbamate, lamotrigine, phenytoin, phenobarbital and valproate against sound-induced seizures in DBA/2 mice. The degree of potentiation induced by DCS was greatest for diazepam, phenobarbital, phenytoin and valproate, less for carbamazepine and least for lamotrigine and felbamate. The increase in anticonvulsant activity was usually associated with a comparable increase in motor impairment. However, the therapeutic index of the combined treatment of the above drugs+DCS, was more favourable than the same drugs+saline with the exception of DCS+carbamazepine and DCS+lamotrigine. Since DCS did not significantly influence the total and free plasma levels of the anticonvulsant drugs studied, pharmacokinetic interactions, in terms of plasma levels, are not probable. The possibility that DCS can modify the clearance from the brain of the anticonvulsant drugs studied cannot be excluded. DCS did not significantly affect the hypothermic effects of the anticonvulsants tested. In conclusion, DCS potentiates the anticonvulsant action of some classical antiepileptic drugs, most notably diazepam, phenobarbital, phenytoin and valproate.

Enhanced susceptibility of pentylenetetrazole kindled mice to quinolone effects

The present study was designed to examine the ability of different quinolones to affect the seizure severity and the latency of development of chemical kindling produced by repeated treatment using a subconvulsant dose of pentylenetetrazole (PTZ). A group of mice (kindled control) were treated subcutaneously (s.c.) with vehicle + PTZ (30 mg/kg, three times a week) for 6 consecutive weeks and the changes in excitability associated with the kindling state were observed over the following 2 h. A second group of mice were injected intraperitoneally (i.p.) with the following quinolone derivatives, ciprofloxacin (ciprox), pefloxacin (peflox), ofloxacin (oflox), cinoxacin (cinox), nalidixic acid (nalidixic), 1-cyclopropyl-6-amino-7-tetrahydroisoquinoline-8-methyl-4-oxo-1,4-dihydr oquinoline-3-carboxylic acid (M5) and 1-cyclopropyl-7-tetrahydro-isoquinoline-8-methyl-4-oxo-1,4-dihydroquinol ine-3-carboxylic acid (MH5) at a dose of 20 mg/kg 15 min before receiving a subconvulsant dose of PTZ (30 mg/kg, s.c.). The results showed that pretreatment with some of the quinolones tested facilitated the development of kindling to PTZ-induced seizures. In particular, ciprox, peflox, oflox, M5 and MH5 derivatives variously increased the development of kindling to PTZ induced seizures, whilst cinox and nalidix did not significantly affect it. Additionally we determined whether the enhanced susceptibility of kindled mice only occurred after relatively short intervals following the last seizure or whether it was a more permanent phenomenon. For the study of the persistence of kindling, the animals were rechallenged with the kindling stimulus (PTZ 25 mg/kg, s.c.) 15 and 30 days after the last injection of the chronic treatment with PTZ (30 mg/kg, s.c.) and the behavioural changes in the kindled mice were compared with the control ones (chronically treated with vehicle). The present data demonstrated that kindling produced long-lasting alterations, substantiating that epileptogenesis initiated by kindling renders the brain more susceptible to central nervous system (CNS) side effects of quinolones. An interaction between PTZ and quinolone derivatives which involves either an inhibition of gamma-aminobutyric acid (GABA) neurotransmission or/and an increase in the function of the excitatory amino acid (EAA) system is suggested.

Effects of novel 6-desfluoroquinolones and classic quinolones on pentylenetetrazole-induced seizures in mice

There have been several reports that convulsions, although rare, occur in patients who receive fluoroquinolones. In this study, the proconvulsant effects exhibited by a novel series of 6-desfluoroquinolones and some classic quinolones on pentylenetetrazole (PTZ)-induced seizures in mice were evaluated and compared. Animals were intraperitoneally injected with vehicle or quinolone derivatives (5 to 100 microg/g of body weight) 30 min before the subcutaneous (s.c.) administration of PTZ (40 microg/g). In each experiment, mice were then observed for 1 h to monitor for the incidence and onset of clonic seizures. The order of proconvulsant activity in our epileptic model was MF5184 > MF5187 > pefloxacin > MF5189 > ofloxacin > ciprofloxacin > MF5140 > MF5181 > MF5137 > rufloxacin > MF5143 > MF5158 > MF5191 > MF5128 > MF5138 > cinoxacin > MF5142 > norfloxacin > nalidixic acid. The relationship between the chemical structure and the proconvulsant activity of 6-desfluoroquinolone derivatives was studied. We observed that, in terms of toxicity to the central nervous system (CNS), besides the heterocyclic side chain (moiety) at the C-7 position, the C-6 substituent also appears to play an important role. In particular, a hydrogen at the C-6 position seemed to be responsible for major neurotoxic activity in comparison to an amino group located in the same position. The relationship between lipophilicity and proconvulsant activity was also investigated. We did not find any clear relationship between a higher level of lipophilicity and major proconvulsant properties. Although the principal mechanism by which quinolones induce potentiation of the proconvulsant effects of PTZ cannot be easily determined, it is possible that the convulsions are caused by drug interactions, because both PTZ and quinolones are believed to increase excitation of the CNS by inhibition of gamma-aminobutyric acid binding to receptors.

Reduced plasma c-AMP levels in children with atopic dermatitis

Plasma levels of cAMP and serum concentrations of IgE have been determined in children with acute atopic dermatitis (AD) and in a healthy control group, to illuminate the pathophysiological mechanisms that cause AD. There were significantly lower plasma levels of cAMP (P < 0.001) and significantly higher levels of serum IgE (P < 0.004) in children with AD, in comparison with a healthy control group. It is possible that defective control of c-AMP levels could contribute to the immunopathogenesis of AD and monitoring levels may be of value in the clinical evaluation of the disease.

Morphological and immunohistochemical considerations on the basal ganglia in pigeon (Columba livia)

Morphological and immunohistochemical studies carried out particularly around the level of the basal ganglia (BG) in birds, are reported and commented on. Our results showed, on paraffin embedded avian BG, both the histological features and the immunohistochemical findings on immunofluorescence distribution of some neuropeptides (especially Metenkephalin) in the striatal complex. By comparing our results of Metenkephalin immunoreactivity (Menkir) with the referred analogous ones of Substance P (SP) quoted in literature, we confirmed the strikingly similar labelling at the levels of the Lobus paraolfactorius (LPO) and Paleostriatum augmentatum (PA), in contrast with the very low immunoreactivity at the Paleostriatum primitivum (PP) levels. We were able also to demonstrate the strong MEnk-ir of the neurons of the Nucleus accumbens, Nucleus septalis and paraventricularis. All these findings are also in accord to the interpretation by many AA (Wynne and Gunturkun, 1995; Reinez et al., 1983), about the anatomical correspondence between the LPO-PA complex of birds and the caudate-putamen in mammals. Some MEnk + 'wooly like fibres' described in our specimens in the PA (on the contrary reported in the Gpe segment of mammals) apparently escape these correspondence.

Tolerance and pharmacokinetics of ciprofloxacin in the chick. Preliminary experience in subjects of pediatric age with urinary tract infections (UTI)

We studied the tolerance and pharmacokinetic parameters of ciprofloxacin in (2 mg/kg, i.v.) in 45 chicks. Serum concentrations of ciprofloxacin at various times of drawing (15 min, 30 min, 1 hr, 3 hr, 6 hr, 8 hr and 12 hr) peaked in the first 15 min with a trough after 6 hr, and were completely absent after 8 hr. We found no neurotoxic effects or behavioral changes. Encouraged by a good tolerance for this quinolone, we conducted a preliminary study concerning the therapeutic efficacy of ciprofloxacin in 8 subjects of pediatric age (8-14 years) with urinary tract infections (UTI) that are resistant to classic antibiotics. The results and normality of hematologic parameters, checked before and after therapy, allow us to recommend the monitored use of ciprofloxacin in children with UTI resulting from bacteria resistant to other antibiotics.

Comparative epileptogenic properties of two monobactam derivatives in C57, Swiss and DBA/2 mice

The behavioural and electrocortical effects of two monobactam derivatives were studied after intraperitoneal (ip) administration in DBA/2 mice, a strain genetically susceptible to sound-induced seizures, and in C57 and Swiss mice, two strains not prone to seizure. DBA/2 mice were more susceptible than Swiss and C57 mice to seizures induced by aztreonam or carumonam. No significant differences were observed between seizures elicited by aztreonam and carumonam in animals (DBA/2 only) administered intracerebroventricularly or ip. Although the main mechanism for seizure-like activity of monobactams cannot be easily determined, we believe that several mechanisms may be involved. An increased excitation of the central nervous system (CNS) by inhibition of GABA binding to receptors and a slow clearance of aztreonam and carumonam from the CNS may be postulated.

GABA concentrations in different cerebral areas of bass (dicentrarchus labrax)

In these investigations GABA concentrations in different cerebral areas (cortex, diencephalon, optic lobes and mesencephalon) of bass (Dicentrarchus labrax) were evaluated. According to the results obtained, the GABA, like other chemical mediators (noradrenaline, dopamine, serotonin), investigated in different animal species, shows a variable distribution in the CNS of bass. The highest levels of GABA were observed in the cerebral cortex and the lowest ones in the mesencephalon. Mean values were observed in the diencephalon and the optic lobes. The study of the GABA-ergic system of the CNS of fish, could provide a valid contribution to the comprehension of several biochemical and physiopathological mechanisms responsible for the behavioural activity and/or the appearance of neurotoxic phenomena.

Stimulatory effects on lactotrophs and crop-sac of interleukin-1 and interleukin-2 in pigeons (Columba livia)

The ultrastructural effects of human-recombinant interleukin-1 beta (IL-1 beta) and human-recombinant interleukin-2 (IL-2) on the crop-sac (the target organ for prolactin secretion in birds) and the anterior pituitary lactotrophs, were studied in pigeons (Columba livia). The intraventricular microinfusion of the two interleukins produced maximal crop-sac stimulation with milk-like secretion, as demonstrated by the observation of ultrastructural changes in the lactiferous areas through scanning and transmission electron microscopy of crop-sac mucosa. A marked activation of the anterior pituitary lactotrophs was also observed. Crop-sac and pituitary lactotrophs stimulatory effects were prevented by a previous intraventricular treatment with monoclonal antibodies for IL-1 beta and IL-2 receptors, but not by an intraperitoneal administration of naloxone. The present results show that interleukins possess in pigeons marked stimulatory effects on prolactin secretion and that these are mediated by specific receptors.

Ribavirin-induced behavioral, body temperature and electrocortical spectra effects in the rat

Behavioral, electrocortical spectra and body temperature effects, following a single intracerebroventricular (i.c.v.) or intraperitoneal (i.p.) injection of ribavirin, were studied in male adult rats. Ribavirin, when administered i.p., induced squatting posture, sedation, electrocortical synchronization, piloerection and a slight decrease of tactile and/or auditory stimuli/responses lasting from 45 min to 16 hr, as well as a longer lasting hypothermic effect. Following i.c.v. administration, ribavirin (50, 100 and 200 micrograms) elicited a soporific effect and produced changes in the electrocortical spectra. Pretreatment, 15 min before, with either prazosin (10 mg/kg, i.p.), an alpha 1-adrenoceptor blocker, or piperoxan (20 mg/kg, i.p.) and yohimbine (1 mg/kg, i.p.), two alpha 2-adrenoceptor blockers, or naloxone (1 mg/kg, i.p.), an opioid antagonist, did not prevent the hypothermic and behavioral effects induced by i.p. or i.c.v. administration of ribavirin. The present findings exclude an involvement of alpha-adrenergic and opioid neurotransmission in mediating the hypothermic, electrocortical and behavioral effects induced by ribavirin.

Evaluation of cefotaxime concentrations in rat cerebral areas and serum by microbiological method and HPLC

The aim of the investigation was to verify the reliability and sensitivity of High Performance Liquid Chromatography (HPLC), compared to the classic microbiological method of plate diffusion, in evaluating cefotaxime concentrations in some cerebral areas and serum of the rat. The mean concentration of cefotaxime in the serum (after acute administration of 15 mg/kg i.m.) was 20 micrograms/ml with the microbiological method and 23 micrograms/ml with HPLC. No antibiotic was detectable, with both methods, in the cerebral areas. The results with both methods are in good accordance, although the HPLC technique is more sensitive and accurate.

Lack of effects of thallium on GABAergic mechanisms in discrete areas of the rat brain

The effects of intramuscular treatment for 3 and 5 consecutive days with thallium sulphate (2.5, 5 and 10 mg/Kg) on GABA content, glutamate - decarboxylase (GAD) and GABA-transaminase (GABA-T) activity in different areas of the rat brain were studied. Thallium at the dose levels used did not produce significant changes in GABA content, GAD and GABA-T activity in the brain hemispheres, brainstem, hypothalamus, diencephalon and caudate nucleus.

Long-lasting hypothermic effects of vincristine in rats

The effects of vincristine given intravenously on deep and superficial body temperature were assessed in rats kept at ambient temperature within the thermoneutral range. Vincristine (0.5 and 1 mg/kg i.v.) produced a gradual but marked hypothermic response which was dose-dependent, reached its maximum after approximately 3 h and lasting approximately 48 h. Vincristine induced a decrease in deep body temperature which was accompanied by piloerection and a decrease in skin temperature. Pretreatment with phentolamine, an alpha-adrenoceptor blocking agent (0.5 mg/kg i.v. 15 min before) prevented the hypothermic effects induced by subsequent administration of vincristine (0.5 mg/kg i.v.). These experiments showed that vincristine produced a marked hypothermic response in rats. However, the precise site of action remains to be established.

Behavioral and electrocortical effects after intrastriatal cefazolin in rats are antagonized by drugs enhancing GABA-ergic transmission

Cefazolin, a semisynthetic cephalosporin, reported to reproduce in several animal species an experimental model of epilepsy, was microinjected into the head of the caudate nucleus in rats. The effects on behavior, electrocortical activity and the antagonism by GABA receptor agonists and GABA-transaminase activity inhibitors were studied. Cefazolin given into the III cerbral ventricle produced an intense pattern of behavioral and locomotor stimulation culminating into several episodes of wild-running crisis, myoclonic jerks of the limbs and in some occasions generalized clonic seizures, these effects lasting over 2 h. At the same time bursts of electrocortical high-voltage spikes followed bu intermittent high-voltage single spikes were recorded. Similarly cefazolin, given into the caudate nucleus produced contralateral circling, an increase locomotor activity, myoclonic jerks of contralateral limbs, intense stereotyped behavior and occasionally generalized clonic convulsions. In addition postural changes consisting in tonic contralateral head-neck deviation were observed. This picture was accompanied by epileptic electrocortical changes, i.e. high-voltage spikes, spike-waves complexes, recruiting polyspikes. The subsequent intraventricular or intrastriatal infusion of GABA, GABOB, muscimol or of GABA-transaminase inhibitors, ethanolamine-o-sulphate and GABA-vinyl-GABA was able to antagonize clinical and electrocortical changes evoked by cefazolin. In conclusion, the present results suggest that cefazolin motor and electrocortical effects are due to an impairment of GABA-ergic transmission.

Enhanced behavioural, electrocortical and hyperthermic effects of serotonin-like agents after impairment of serotonin transmission in fowl brain

In adult fowls and in young chicks (Gallus domesticus) the effects were studied on body temperature, behaviour and electrocortical activity of 5-HT and other direct or indirect serotonin agonists given into the III cerebral ventricle in conditions of prolonged impairment of serotoninergic transmission. In chicks pretreated with 5,6-dihydroxytryptamine the subsequent intraventricular injection of 5-HT produced more intense and longer-lasting hyperthermic response and behavioural and electrocortical sleep. On the other hand fenfluramine given intraventricularly in fowls pretreated with 5,6-DHT did not produce significant body temperature and behavioural changes. After 14 and 21 day treatment with methysergide the subsequent administration of 5-HT, fenfluramine and quipazine produced in fowls an hyperthermic response and behavioural sleep more marked and longer-lasting than in control animals. The present experiments show that in conditions of chronic impairment of 5-HT function there is an enhanced behavioural and body temperature response to 5-HT and drugs acting by releasing endogenous 5-HT or 5-HT agonists.

Effects of intraventricular beta-endorphin and D-ALA2-methionine-enkephalinamide on behaviour, spectrum power of electrocortical activity and body temperature in chicks

In chicks (Gallus domesticus) the effects of beta-endorphin and D-Ala-2-methionine-enkephalinamide given into the third cerebral ventricle on behaviour, electrocortical activity and body temperature were studied. Dose-dependent behavioural stuporous state, decrease in painful stimuli and hypothermic effects were observed after both peptides. Electrocortical high-amplitude slow frequency waves occurred during behavioural sedation and stupor. Spectrum power analysis has allowed to quantify the ECoG activity and has revealed an increase in total voltage output with a predominant increase within the lower spectrum frequencies. The hypothermic effects were significantly more marked when chicks were kept at ambient temperature below their thermoneutral range. Behavioural, electrocortical and body temperature effects were rapidly reversed by naloxone showing that these effects are mediated through an activation of specific opioid receptors.

Central effects of histamine and H1 and H2 receptors agonists and antagonists after intraventricular infusion in fowls

In adult fowls (Gallus deomesticus) the effects of histamine H2 and H2 histamine receptors angonists and antagonists infused into the III cerebral ventricle were studied on behaviour, electrocortical activity and body temperature. Histamine produced biphasic effects, i.e. an initial period of electrocortical synchronization was followed by a longer-lasting behavioural stimulation, electrocortical desynchronization and shivering. Body temperature was increased in a dose-dependent manner. Dimaprit, an agonist at H2 receptors, produced behavioural and electrocortical sleep and decreased body temperature whereas, 2-(2-thiazolyl-)-ethyl-amine, an agonist at H1 receptors, behavioural stimulation, electrocortical desynchronization, vocalization and hyperthermia. Cimetidine, an antagonist at H2 receptors, produced intense behavioural stimulation and electrocortical desynchronization accompanied by vocalization, tachypnoea, occasional escape responses and stereotypies. Body temperature was increased. Mepyramine, an antagonist at H1 receptors, produced behavioural and electrocortical sleep and prevented behavioural excitation elicited by subsequent infusion of histamine and hyperthermia evoked by 2-(2-thiazolyl -ethylamine. Haloperidol, a neuroleptic drug, sharing with mepyramine membrane stabilizing properties, was unable to antagonize histamine-induced behavioural excitation. In conclusion, present experiments provide pharmacological evidence for the existence of H1 and H2 histamine receptors in avian brain and suggest an involvement of histamine H1 and H2 receptors in the control of arousal-sleep and thermoregulatory mechanisms.

Effects of intraventricular beta-endorphin on GABA system in some areas of chick brain

In chicks with cannulae chronically implanted into the III cerebral ventricle, the effects of a single dose (10 micrograms) of beta-endorphin on GABA and free glutamic acid content, GAD and GABA-T activities in the diencephalon, brain-stem and brain hemispheres were studied at the time of maximal behavioural stuporous state and analgesia. A significant decrease in GABA concentration both in the diencephalon and brain-stem, accompanied by a significant increase in GABA-T activity in the same areas, was shown to occur. No changes were observed in GAD activity and in glutamic acid content in the studied areas of the brain. In conclusion, present experiments suggest that some central effects of a beta-endorphin may be due to an interference with GABA-ergic transmission.