Development of tubulin polymerization inhibitors as anticancer agents

INTRODUCTION

Microtubules are intracellular, filamentous, polymeric structures that extend throughout the cytoplasm, composed of α-tubulin and β-tubulin subunits. They regulate many cellular functions including cell polarity, cell shape, mitosis, intracellular transport, cell signaling, gene expression, cell integrity, and are associated with tumorigenesis. Inhibition of tubulin polymerization within tumor cells represents a crucial focus in the pursuit of developing anticancer treatments.

AREAS COVERED

This review focuses on the natural product and their synthetic congeners as tubulin inhibitors along with their site of interaction on tubulin. This review also covers the developed novel tubulin inhibitors and important patents focusing on the development of tubulin inhibition for cancer treatment reported from 2018 to 2023. The scientific and patent literature has been searched on PubMed, Espacenet, ScienceDirect, and Patent Guru from 2018-2023.

EXPERT OPINION

Tubulin is one of the promising targets explored extensively for drug discovery. Compounds binding in the colchicine site could be given importance because they can elude resistance mediated by the P-glycoprotein efflux pump and no colchicine site binding inhibitor is approved by FDA so far. The research on the development of antibody drug conjugates (ADCs) for tubluin polymerization inhibition could be significant strategy for cancer treatment.

Optimizing the Agrobacterium tumifaciens mediated transformation conditions in Colletotrichum lindemuthianum: A step forward to unravel the functions of pathogenicity arsenals

Colletotrichum lindemuthianum is a hemibiotrophic fungal pathogen that causes bean anthracnose and it is rated among the top 10 important diseases infecting beans. Currently our knowledge on molecular mechanisms underlying C. lindemuthianum pathogenesis is limited. About five pathogenicity genes have been identified in C. lindemuthianum using Restricted Enzyme Mediated Integration (REMI) and the transformation using Agroinfection has not been optimized. In this study, a series of experiments were conducted to optimize the key parameters affecting the Agrobacterium tumefaciens- mediated transformation (ATMT) for C. lindemuthianum. The transformation efficiency increased with increase in spore concentration and co-cultivation time. However, the optimum conditions that yielded significant number of transformants were 10⁶ ml^-1 spore concentration, co-cultivation time of 72 h, incubation at 25ºC and using a cellulose membrane filter for the co-cultivation. The optimized protocol resulted in establishment of large mutant library (2400). A few mutants were melanin deficient and a few were unable to produce conidia. To determine the altered pathogenicity, two new approaches such as detached leaf and twig techniques proved reliable and require fewer resources to screen the large mutant libraries in a short time. Among the 1200 transformants tested for virulence, 90% transformants were pathogenically similar to wild type (race 2047), 96 and 24 were reduced and impaired, respectively. The altered avirulent transformants can prove vital for understanding the missing link between growth and developmental stages of pathogen with virulence. This platform will help to develop strategies to determine the potential pathogenicity genes and to decipher molecular mechanisms of host-pathogen interactions in more detail.

Heat induction in two-dimensional graphene-Fe3O4 nanohybrids for magnetic hyperthermia applications with artificial neural network modeling

We report the synthesis and characterization of graphene functionalized with iron (Fe³⁺) oxide (G-Fe₃O₄) nanohybrids for radio-frequency magnetic hyperthermia application. We adopted the wet chemical procedure, using various contents of Fe₃O₄ (magnetite) from 0-100% for making two-dimensional graphene-Fe₃O₄ nanohybrids. The homogeneous dispersal of Fe₃O₄ nanoparticles decorated on the graphene surface combined with their biocompatibility and high thermal conductivity make them an excellent material for magnetic hyperthermia. The morphological and magnetic properties of the nanohybrids were studied using scanning electron microscopy (SEM) and a vibrating sample magnetometer (VSM), respectively. The smart magnetic platforms were exposed to an alternating current (AC) magnetic field of 633 kHz and of strength 9.1 mT for studying their hyperthermic performance. The localized antitumor effects were investigated with artificial neural network modeling. A neural net time-series model was developed for the assessment of the best nanohybrid composition to serve the purpose with an accuracy close to 100%. Six Nonlinear Autoregressive with External Input (NARX) models were obtained, one for each of the components. The assessment of the accuracy of the predicted results has been done on the basis of Mean Squared Error (MSE). The highest Mean Squared Error value was obtained for the nanohybrid containing 45% magnetite and 55% graphene (F₄₅G₅₅) in the training phase i.e., 0.44703, which is where the model achieved optimal results after 71 epochs. The F₄₅G₅₅ nanohybrid was found to be the best for hyperthermia applications in low dosage with the highest specific absorption rate (SAR) and mean squared error values.

Molecular phylogeny, pathogenic variability and phytohormone production of Fusarium species associated with bakanae disease of rice in temperate agro-ecosystems

Bakanae is the emerging disease threating the rice cultivation globally. Yield reduction of 4-70% is recorded in different parts of the world. A total of 119 Fusarium isolates were collected from rice plants at different geographical locations and seeds of different rice cultivars. The isolates were evaluated for morphological, biochemical and pathogenic diversity. The amplification of TEF-1α gene was carried out for exploring the species spectrum associated with the cultivated and pre-released rice varieties. The production of gibberellin varied from 0.53 to 2.26 µg/25 ml, while as that of Indole acetic acid varied from 0.60 to 3.15 µg/25 ml among the Fusarium isolates. The phylogenetic analysis identified 5 different species of the genus Fusarium viz. Fusarium fujikuroi, F. proliferatum, F. equiseti, F.oxysporum and F. persicinum after nucleotide blasting in NCBI. Only two Fusarium spp. F. fujikuroi and F. proliferatum were found to be pathogenic under virulence assays of the isolates. The isolates showed a considerable variation in morphological and pathogenic characters. The isolates were divided into different groups based on morphology and pathogenicity tests. The isolates showed a considerable variation in morphology, phytohormone profile and virulence indicative of population diversity. Three species F. equiseti, F.oxysporum and F. persicinum which have not been reported as pathogens of rice in India were found to be associated with bakanae disease of rice, however their pathogenicity could not be established.

Population structure of Venturia inaequalis, a hemibiotrophic fungus, under different host resistance specificities in the Kashmir valley

Venturia inaequalis is a notorious fungal pathogen and show classical gene for gene interaction with its apple host. Neutral markers provide clues about history, evolutionary potential, genetic diversity and population structure of V. inaequalis. The genetic diversity and population structure of fungus indicates that the pathogen is highly diverse with the capacity to breach the scab resistance genes. In the present study, we collected 108 V. inaequalis isolates from three apple cultivars differing in Rvi1 resistance gene. Based on the AMOVA, the variation was mostly distributed among the isolates, providing evidence of non-existence of subpopulation in orchards thus founder population is difficult to arise in Kashmir apple orchards. Pair wise genetic differentiation is less due to regular occurrence of gene flow between the populations residing on different orchard as infected material is transported without stringent quarantine measures. Based on principal coordinate analysis and clustering algorithm as implemented in STRUCTURE, we observed admixture between the two subpopulations, which is quite low, suggesting the existence of pre-zygotic and post-zygotic barriers to gene flow and we cannot rule out the existence of other structures shared by accessions belonging to different varieties. Due to the continuous increase in introduction and monoculture of apple varieties, mixed orchard with different host resistance specificities are more suitable for managing the apple scab in Kashmir valley.

Can extent of high grade dysplasia in Barrett's oesophagus predict the presence of adenocarcinoma at oesophagectomy?

BACKGROUND

Optimal management of Barrett's oesophagus complicated by high grade dysplasia is controversial. Recently, the extent of high grade dysplasia was described as a predictor of subsequent development of cancer in patients undergoing continued surveillance. However, there is no universal agreement on the definition of extent of high grade dysplasia.

AIM

To determine if extent of high grade dysplasia in Barrett's oesophagus is a predictor of the presence of adenocarcinoma at the time of oesophagectomy.

METHODS

Forty two patients with Barrett's oesophagus and high grade dysplasia who underwent oesophagectomy between 1985 and 1999 were identified from a prospective database. All pathological specimens, including preoperative endoscopic biopsies and post-oesophagectomy sections, were reviewed in a blinded fashion by one expert gastrointestinal pathologist to determine the extent of high grade dysplasia. The extent of high grade dysplasia was defined using two different criteria, one from the Cleveland Clinic and one from the Mayo Clinic.

RESULTS

Twenty four of 42 patients (57%) had unsuspected cancer at the time of oesophagectomy. Using the Cleveland Clinic definition, 10 of 21 (48%) patients with focal high grade dysplasia had carcinoma compared with 14 of 21 patients (67%) with diffuse high grade dysplasia (p=0.35). Using the Mayo Clinic definition, adenocarcinoma was found in five of seven (72%) patients with focal high grade dysplasia compared with 19 of 35 (54%) with diffuse high grade dysplasia (p=0.68).

CONCLUSIONS

The extent of high grade dysplasia, regardless of how it is defined, does not predict the presence of unsuspected adenocarcinoma at oesophagectomy. There is no evidence as yet that the extent of high grade dysplasia can be used as a basis for decision making in these patients.

Modulation of ethanol-induced motor incoordination by mouse striatal A(1) adenosinergic receptor

We have demonstrated that ethanol-induced motor incoordination is modulated by cerebellar adenosine A(1) receptor. This study represents an extension into another important brain motor area, the striatum that, unlike cerebellum, has high density of both A(1) and A(2A) receptors. Direct intra-striatal micro-infusion of Ro15-4513 (0.05, 0.5, 1 ng), a partial inverse-agonist of benzodiazepine, significantly and nearly dose-dependently attenuated ethanol-induced motor incoordination indicating mediation of ethanol's motor incoordination by striatum. Intra-striatal A(1)-selective agonist N(6)-cyclohexyladenosine (CHA; 1, 2, 4 ng), A(1) = A(2A) non-selective agonist, 5'-N-ethylcarboxamidoadenosine (NECA; 1.5, 3, 6 ng), and A(1)-selective antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; 25, 50, 100 ng) dose-dependently accentuated and attenuated, respectively, ethanol-induced motor incoordination, strongly suggesting modulation by striatal adenosine A(1) receptor. Intra-striatal DPCPX significantly antagonized not only ethanol-induced motor incoordination but also its potentiation by intra-striatal CHA, R-(+)-N(6)-(2-phenylisopropyladenosine) (R-PIA), or NECA. No change in motor coordination occurred after the highest dose of CHA, R-PIA, or NECA followed by saline. Similarly, the highest intra-striatal dose of Ro15-4513 or DPCPX neither altered motor coordination or locomotor activity indicating relative selectivity of interaction with ethanol. Nearly 25-fold higher dose of A(2A)-selective agonist, CGS-21680, compared to CHA was necessary to produce a comparable potentiation of ethanol's motor incoordination perhaps suggesting a lack of or less significant striatal A(2A) involvement. Intra-striatal pertussis toxin (0.5 microg) pre-treatment markedly attenuated ethanol-induced motor incoordination as well as its potentiation by intra-striatal CHA. These results support that striatum is one of the brain motor areas mediating the motor impairing effects of acute ethanol and that the latter's modulation occurs via A(1)-selective receptors coupled to pertussis toxin-sensitive G proteins.

Involvement of the cerebellar adenosine A(1) receptor in cannabinoid-induced motor incoordination in the acute and tolerant state in mice

Cannabinoids are known to impair motor function in humans and laboratory animals. We have demonstrated an accentuation of cannabinoid (CP55,940)-induced motor incoordination in mice by the adenosine A(1) receptor-selective agonist N(6)-cyclohexyladenosine (CHA) (4 ng) using an intracerebellar (ICB) microinjection method. This effect was mediated by the A(1) receptor because pre-treatment with ICB 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) (100 ng), an adenosine A(1) receptor selective antagonist, completely abolished the accentuation. Furthermore, ICB pre-treatment with DPCPX (100 ng) before ICB CP55,940 (15 microg) attenuated the motor incoordination suggesting a modulation by an endogenous adenosine A(1) system. ICB microinjection of CHA or DPCPX prior to ICB vehicle had no effect on normal motor coordination. ICB microinjection of dipyridamole (25 microg), an adenosine transport inhibitor, significantly accentuated the motor incoordination by ICB CP55,940 (15 microg), providing further support for the involvement of endogenous adenosine in the action of CP55,940. Tolerance to the motor incoordinating effect of ICB CP55,940 was demonstrated following 3 days of i.p. CP55,940 (0.1, 1 or 2 mg/kg every 12 or 24 h; total of six or three injections, respectively). Interestingly, animals which exhibited tolerance to ICB CP55,940 also demonstrated tolerance to the accentuating effect of ICB CHA suggesting cross-tolerance between adenosine agonists and cannabinoids. Cross-tolerance was also demonstrated following 3 days of i.p. CHA (0.25 or 1 mg/kg every 24 h; total of three injections) as further evidence of the modulatory role of the cerebellar adenosine system in the acute manifestation of CP55,940-induced motor incoordination. The involvement of cerebellar adenosine and the A(1) receptor in cannabinoid actions is circumstantially supported by previous evidence that CB(1) receptors and A(1) receptors are both localized on cerebellar granule cell parallel fiber terminals and basket cell neurons where they serve to inhibit the release of neurotransmitters.

Cannabinoid-induced motor incoordination through the cerebellar CB(1) receptor in mice

Cannabinoids are known to impair motor function in humans and laboratory animals. We have observed dose-dependent motor incoordination in mice evaluated by rotorod following direct intracerebellar (i.c.b.) microinjection of synthetic cannabinoid agonists CP55,940 (5-25 microg) and HU-210 (1.56-6.25 microg), through permanently implanted stainless steel guide cannulas. The motor incoordination was marked at 15, 35 and 55 min post-microinjection. The motor incoordination elicited by HU-210 (6.25 microg) and CP55,940 (20 microg) was significantly blocked by the CB(1) receptor-selective antagonist SR141716A (25 microg i.c.b.), indicating mediation by a cerebellar CB(1) receptor. Further direct evidence of CB(1) mediation was obtained through a CB(1) receptor antisense/mismatch oligodeoxynucleotide approach (3 microg/12 h; total of six doses). Mice treated with intracerebellar antisense had a significantly diminished motor incoordination response to intracerebellar CP55,940 15 microg compared to mice that received intracerebellar mismatch or no prior treatment. Also, the response to intracerebellar CP55,940 in the CB(1) mismatch-treated mice did not differ from the mice that received only CP55,940. A separate study using a cerebellar tissue punching technique, following intracerebellar [3H]-CP55,940 microinjection, confirmed that cannabinoid drug dispersion following microinjections was exclusively confined to the cerebellum. Microinjection of CP55,940 (20 microg) into the hippocampus, an area with a large density of CB(1) receptors, did not impair motor coordination. Taken together, these results indicate that cannabinoid-induced motor impairment occurs by activation of a CB(1) receptor in the cerebellum. The participation of other brain motor areas in cannabinoid-induced motor incoordination will require future study.

Cerebellar CB(1) receptor mediation of Delta(9)-THC-induced motor incoordination and its potentiation by ethanol and modulation by the cerebellar adenosinergic A(1) receptor in the mouse

The effect of intracerebellar microinfusion of antisense oligodeoxynucleotide to Delta(9)-tetrahydrocannabinol (Delta(9)-THC) and other naturally occurring cannabinoid receptor (CB(1)) mRNA on Delta(9)-THC-induced motor impairment was investigated in mice. Delta(9)-THC (15-30 microgram/microliter intracerebellar) resulted in a significant motor impairment in a dose-related manner. The intracerebellar pretreatment with antisense oligodeoxynucleotide (3.0 microgram/100 nl/12 h; six administrations/mouse) virtually abolished Delta(9)-THC (15 and 25 microgram/1 microliter intracerebellar)-induced motor impairment. However, intracerebellar pretreatment with the mismatched oligodeoxynucleotide in exactly the same manner as the antisense was completely ineffective in altering the Delta(9)-THC-induced motor impairment. These results strongly suggest the involvement of CB(1) receptor in the expression of Delta(9)-THC-induced motor impairment. The intracerebellar microinfusion of adenosine A(1)-selective agonist, N(6)-cyclohexyladenosine (CHA) (4 ng/100 nl) significantly enhanced Delta(9)-THC-induced motor impairment, suggesting a cerebellar A(1) adenosinergic modulation of motor impairment. A pretreatment with the antisense and the mismatched oligodeoxynucleotide also markedly attenuated and did not alter, respectively, the cerebellar A(1) adenosinergic modulation (enhancement) of Delta(9)-THC-induced motor impairment. There was no change in the normal motor coordination due to intracerebellar pretreatment with antisense and its mismatch, in the presence as well as absence of intracerebellar CHA indicating the selectivity of interactions with Delta(9)-THC. The Delta(9)-THC-induced motor incoordination was also significantly enhanced dose-dependently by systemic (i.p.) ethanol administration suggesting behavioral synergism between the two psychoactive drugs. Pretreatment (intracerebellar) with pertussis toxin (PTX) markedly attenuated Delta(9)-THC- and Delta(9)-THC+CHA-induced motor incoordination suggesting coupling of CB(1) receptor to PTX-sensitive G-protein (G(i)/G(o)). These data suggested co-modulation by cerebellar cannabinoid and adenosine system of Delta(9)-THC-induced motor impairment. Conversely, the results in the present study also suggested co-modulation by cerebellar adenosine A(1) and CB(1) receptors of ethanol-induced motor impairment, thereby indicating a possible common signal transduction pathway in the expression of motor impairment produced by Delta(9)-THC as well as ethanol.

Rat striatal adenosinergic modulation of ethanol-induced motor impairment: possible role of striatal cyclic AMP

We have previously reported the involvement of the striatum in acute ethanol-induced motor incoordination and the striatal adenosinergic modulation of ethanol-induced motor incoordination through A1 receptor-mediated mechanism(s). The present study, a continuation of our previous work, was carried out to investigate the possible functional correlation between striatal cyclic AMP and ethanol-induced motor incoordination, and its modulation by striatal adenosine in Sprague-Dawley rats. Forskolin (0.1, 0.5 and 1.0 pmol), a known activator of adenylate cyclase, significantly attenuated ethanol-induced motor incoordination in a dose-dependent manner following its direct intrastriatal microinfusion. Forskolin also antagonized the accentuating effect of intrastriatal N6-cyclohexyladenosine on ethanol-induced motor incoordination. These results suggested that ethanol-induced motor incoordination might be functionally correlated to a decrease in the striatal cyclic AMP levels and that the striatal adenosine A1 receptors might modulate ethanol-induced motor incoordination through cyclic AMP signaling mechanism(s). Further support to this hypothesis was obtained by the actual measurement of the striatal cyclic AMP levels in the same experimental conditions as in motor coordination studies using high-performance liquid chromatography with fluoroscence detection. Regardless of the method (focused microwave irradiation, cervical dislocation or decapitation into a dry ice-ethanol mixture) used to kill the animals, a significant decrease in the striatal cyclic AMP levels was observed due to ethanol. Intrastriatal adenosine A1-selective agonist, N6-cyclohexyladenosine (24 ng), caused a further significant decrease in the striatal cyclic AMP levels in the ethanol- but not in the vehicle-treated animals. The further enhancement in the ethanol-induced decrease in the striatal cyclic AMP levels by intrastriatal N6-cyclohexyladenosine, therefore, functionally correlated with the observed potentiating effect of intrastriatal N6-cyclohexyladenosine on ethanol-induced motor incoordination. The effects of intrastriatal N6-cyclohexyladenosine+ethanol and of ethanol alone on the striatal cyclic AMP levels were blocked by intrastriatal pertussis toxin (500 ng) pretreatment, indicating the involvement of pertussis toxin-sensitive G-proteins (Gi, Go) and possibly of the adenosine A1 receptor coupled to the G-proteins in the striatum. Furthermore, ethanol alone significantly decreased the basal as well as the cyclic AMP-stimulated catalytic activities of the striatal cyclic AMP protein kinase, which were further reduced by intrastriatal N6-cyclohexyladenosine. The results of the present study therefore support an involvement of a cyclic AMP signaling pathway in the striatal adenosinergic modulation of ethanol-induced motor incoordination at the post-adenosine A1 receptor level.

Adenosinergic modulation of ethanol-induced motor incoordination in the rat motor cortex

1. On going work in our laboratory has shown that adenosine modulates ethanol-induced motor incoordination (EIMI) when given systemically as well as directly into the cerebral ventricles, cerebellum and corpus striatum of the rat and/or mouse. 2. The objective of this study was to determine what effect adenosine agonists and antagonists would have within the rat motor cortex on EIMI. 3. The participation of the motor cortex in EIMI was suggested when microinfusion of the anti-ethanol compound, Ro15-4513, an inverse agonist of the benzodiazepine binding site, directly into the motor cortex significantly attenuated EIMI. Further, the adenosine agonists N6-cyclohexyladenosine (CHA) and 2-p-(2-carboxyethyl)-phenethylamino-5'-N-carboxaminoadenosine++ + hydrochloride (CGS-21680) significantly accentuated EIMI in a dose-related manner. The adenosine A1 receptor-selective agonist, CHA, appeared most potent in this modulatory effect when compared to the A2-selective agonist, CGS-21680. 4. The extent of diffusion of the adenosine drugs within the cortical tissue after their microinfusion was also checked by measuring the dispersion of microinfused [3H]CHA. The [3H]CHA dispersion study indirectly confirmed that the results of the present investigation were based on the effect of adenosine drugs within the motor cortex only. 5. Accentuation by the A1- and A2-selective adenosine agonists was significantly attenuated by the A1-selective antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) but not by the A2 receptor-selective antagonist 8-(3-chlorostyryl)caffeine (CSC) further suggesting modulation mainly by the A1-subtype. 6. Pretreatment of the motor cortex with pertussis toxin (PT) significantly reduced the capacity of both A1- and A2-selective adenosine agonists to accentuate EIMI suggesting the involvement of a PT-sensitive Gi/Go protein. 7. These data support earlier work which showed that adenosine modulates EIMI within the central nervous system (CNS), most likely via the A1 receptor, and moreover, extend that work by including the motor cortex as a brain area participating in the adenosinergic modulation of ethanol-induced motor impairment.

Involvement of kappa-opioids in the mouse cerebellar adenosinergic modulation of ethanol-induced motor incoordination

Using rotorod performance as the test response, possible modulation and co-modulation of ethanol-induced motor incoordination by the cerebellar kappa-opioid and adenosine A1 receptors was studied. A dose-related accentuation of ethanol-induced motor incoordination was observed after direct cerebellar microinfusion of three kappa-opioid receptor agonists: U-50488, U-62066, and bremazocine. On the contrary, significant and dose-related attenuation of ethanol's motor impairment was produced by intracerebellar nor-binaltorphimine, a kappa-opioid receptor antagonist. Furthermore, the accentuation by kappa-agonists was virtually abolished by kappa-antagonist nor-binaltorphimine. Therefore, the accentuation and attenuation by kappa-opioid receptor agonists/antagonist, respectively, was through specific kappa-opioid receptors. Pretreatment with the intracerebellar adenosine A1-selective agonist, N6-cyclohexyladenosine, further enhanced the ethanol-induced motor incoordination and its accentuation by intracerebellar kappa-opioid receptor agonists. Ethanol-induced motor incoordination was markedly attenuated by intracerebellar pertussis toxin (PTX) pretreatment, suggesting an involvement of PTX-sensitive G protein in the expression of motor incoordinating effect of ethanol. Additionally, the intracerebellar PTX also markedly attenuated the accentuation by kappa-opioid agonists of ethanol-induced motor impairment, suggesting participation of PTX-sensitive GTP-binding G protein (Gi, Go) in the kappa-opioid modulation of ethanol's motor impairment. It also confirms that kappa-opioid receptors are linked to PTX-sensitive G protein. The functional similarity between kappa-opioid and adenosine A1 receptors in increasing ethanol's motor incoordination, together with their anatomical co-localization primarily on the axons and axonal terminals of the cerebellar granule cells, suggests a possible common catalytic unit of adenylate cyclase as the basis of modulation of ethanol-induced motor incoordination by both receptor mechanisms.

The striatal adenosinergic modulation of ethanol-induced motor incoordination in rats: possible role of chloride flux

Previous studies from our laboratory have provided strong evidence that brain adenosine modulates acute ethanol (i.p.)-induced motor incoordination (MI) through receptor mediated mechanism(s). Recently, we have reported the involvement of the striatum in ethanol-induced MI as well as the striatal adenosinergic modulation of the ethanol-induced motor deficit. The present study was thus designed to further characterize the modulatory effect of striatal adenosine on ethanol-induced MI and to look for its functional correlation with chloride flux within the rat striatum. Intrastriatal microinfusion of adenosine A1 receptor agonist N6-cyclohexyladenosine (CHA) and antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), significantly accentuated and attenuated, respectively, the motor incoordinating effect of ethanol while having no effect on the normal motor coordination in saline-treated control animals. These data confirmed the role of striatal adenosine in ethanol-induced MI. The selectivity of interactions between adenosine A1 agonist and antagonist and ethanol was further confirmed by the study in which neither intrastriatal CHA nor DPCPX significantly altered the MI induced by sodium pentobarbital. Previously, we have shown that intrastriatal Ro15-4513 not only significantly attenuated ethanol-induced MI but also blocked its accentuation by intrastriatal CHA. It is well known that Ro15-4513 antagonizes many, but not all, CNS effects of ethanol by blocking the ethanol potentiation of GABA-stimulated uptake of chloride. Therefore, experiments using striatal microsac preparations were carried out to investigate the possible modulation of chloride conductance by CHA and its relationship to ethanol. High concentrations of CHA (10 and 100 nM) increased the total chloride uptake by the striatal microsacs. Corresponding to the ethanol-adenosine interaction observed behaviorally, a much lower concentration (1 nM) of CHA, being ineffective itself, significantly enhanced the stimulatory action of ethanol on chloride uptake. This effect was blocked by either Ro15-4513 (100 nM) or DPCPX (10 nM). The modulatory effect of GABA and/or ethanol on chloride influx was also evaluated, and the results supported the appropriateness to use striatal microsac preparations in the present study. Overall, the data suggested a functional interaction between ethanol and striatal adenosine and further supported the hypothesis that striatal adenosine might, in part, modulate ethanol-induced MI through its effect on chloride conductance through chloride channels coupled to GABA-benzodiazepine receptor complex.

Mouse cerebellar adenosinergic modulation of ethanol-induced motor incoordination: possible involvement of cAMP

As an extension of our previous work pertaining to brain adenosinergic modulation of ethanol-induced motor incoordination, the effect of direct intracerebellar administration of the A1-selective adenosine agonist, N6-cyclohexyladenosine (CHA) on ethanol-induced motor incoordination was evaluated. Marked accentuation of ethanol-induced motor impairment by CHA was observed. No change in the normal motor coordination was noted when CHA administration was followed by saline instead of ethanol. Intracerebellar cAMP or its analog, 8-(4-chlorophenylthio)-cAMP, significantly inhibited ethanol's motor impairment in a dose-related manner as well as abolished CHA's accentuating effect on ethanol-induced motor incoordination. These observations suggested a possible involvement of cAMP in the adenosinergic modulation and in the expression of ethanol-induced motor incoordination. Further support was provided by the observation of a marked accentuation and attenuation in a dose-related manner of ethanol-induced motor impairment as well as CHA's accentuation of ethanol's motor impairment by intracerebellar miconazole and forskolin, respectively. However, equimolar intracerebellar doses of miconazole and forskolin (inhibitor and stimulator of adenylyl cyclase, respectively) failed to significantly alter ethanol-induced motor incoordination probably due to their mutual functional antagonism. The expression of adenosinergic modulation and that of ethanol-induced motor impairment most likely involved Gi protein-coupled receptor(s) (such as adenosine receptors). The involvement of receptors linked to pertussis toxin-sensitive G-proteins was suggested because intracerebellar pertussis toxin pretreatment markedly inhibited ethanol-induced motor incoordination as well as CHA's accentuation of ethanol's motor impairment. Finally, cAMP, unlike its antagonism to CHA's accentuation, failed to antagonize the accentuation of ethanol-induced motor impairment by intracerebellar GABA(A) agonist (+)-muscimol. This indicated selectivity of cAMP participation in G protein coupled receptor (such as adenosine)-mediated response and not in ionic channel coupled receptor (such as GABA(A))-mediated mechanism. Overall, the data suggested a possible involvement of cerebellar adenylyl cyclase-cAMP signalling pathway in the adenosinergic modulation of ethanol's ataxia.

Dispersion characteristics of [3H]-labeled adenosine agonist/antagonist following their intrastriatal microinfusion

Following their intrastriatal microinfusion, the dispersion patterns of an adenosine receptor agonist (N6-cyclohexyladenosine) and an antagonist (8-cyclopentyl-1,3-dipropylxanthine) within the striatal tissue were investigated in Sprague-Dawley rats. The [3H]-labeled ligands were microinfused into the striatum of conscious rats through preimplanted guide cannulae in the volume of either 200 (0.1 microCi) or 1000 nl (0.5 microCi) and the animals were killed 15 or 30 min later. The diffusion of the radioactive ligands was evaluated by measuring the radioactivity in the striatal tissue samples using a tissue punching technique. When the volume of microinfusion was 200 nl, the diffusion within the striatum was limited as the radioactivity remained confined to the immediate vicinity of microinfusion site regardless of the postmicroinfusion time (15 or 30 min). The pattern of tissue diffusion was similar at 15 min after the intrastriatal microinfusion of 1000 nl of [3H]-ligands. At 30 min after the intrastriatal microinfusion of 1000 nl volume, a relatively larger area of striatal tissue was covered by the drug solution. In addition, the 1000 nl intrastriatal microinfusion probably resulted in the diffusion of some of the drug solution into the extrastriatal area since small but significant radioactivity was detected at sites outside the striatum. The intrastriatal diffusion of the [3H]-ligand solution was not uniform in all directions from the site of microinfusion. The relationship between the amount of radioactivity remaining at the site of microinfusion and the postmicroinfusion time was inverse. Additionally, at the same postmicroinfusion time (15 or 30 min), a lower percent of the total microinfused radioactivity was found remaining at the microinfusion site with the 1000 nl microinfusion volume than that with the 200 nl volume. Overall, the diffusion patterns of intrastriatal adenosine agonist and antagonist were similar. The results of the present investigation suggest that both the microinfusion volume and the postmicroinfusion time may be important factors in determining the diffusion pattern and tissue content of intrastriatally microinfused adenosine drugs. This information could be important for the correct understanding and interpretation of the data from studies involving drug microinfusions.

Antagonism by intracerebellar Ro15-4513 of acute ethanol-induced motor incoordination in mice

The possible antiethanol effect of intracerebellarly microinjected Ro15-4513 was investigated using motor incoordination as the test response. The results of this study further confirmed reports from this and other laboratories that this partially negative ligand of benzodiazepine selectively attenuated and nearly reversed the motor impairment of acute ethanol. The attenuation observed after microinjections of doses of 0.05, 0.1, and 0.5 ng was significant and dose related. There was no effect on normal coordination when the highest dose, 0.5 ng, was administered followed by saline instead of a test dose of ethanol. When 0.5 ng of Ro15-4513 alone was microinjected into the cerebellum, no significant change in the locomotor activity was observed. Even a 10-fold higher intracerebellar dose (5 ng) of Ro15-4513 administered alone produced no significant changes in locomotor activity. This suggests that attenuation of ethanol-induced motor incoordination was most likely due to the selective antiethanol effect of Ro15-4513 at the dose range used in the present investigation. The antiethanol effect of intracerebellar Ro15-4513 also reaffirmed the well-known belief that the cerebellum is an important brain region for ethanol's motor-impairing effect. The results also indirectly suggest the inhibition of GABAA-gated chloride ion channel activity as the most likely basis of Ro15-4513's antiethanol effect.

Possible role of striatal adenosine in the modulation of acute ethanol-induced motor incoordination in rats

Several reports from our laboratory have suggested the involvement of the brain adenosinergic system in ethanol-induced motor incoordination (EIMI). This study is an extension of the previous work and pertains to the evaluation of the role of the striatal adenosine in EIMI in male Sprague-Dawley rats. Using the motor incoordination induced by 1.5 g/kg of ethanol (ip) as a test response, the possible behavioral interactions between ethanol and adenosine agonists and antagonists in the striatum were investigated. Intrastriatal (IST) administration of adenosine A1-, A1 = A2-, and As-selective agonists, R(-)N6-(2-phenylisopropyl)adenosine (R-PIA), 5'-N-ethylcarboxamido-adenosine (NECA), and 5'-(N-cyclopropyl)-carboxamidoadenosine, respectively, significantly and dose-dependently accentuated EIMI when evaluated by rotorod test, suggesting the striatal adenosinergic modulation of EIMI. No significant change in normal motor coordination was noted, even when the highest IST doses of adenosine agonists were followed by saline instead of ethanol, suggesting that the observed behavioral interactions of these drugs were selective to ethanol. Hippocampus, which is known not to be involved in the normal motor functions, was selected as a control brain area because of the presence of high density of adenosine receptors, as well as the high levels of adenosine. Intrahippocampal NECA failed to alter EIMI, indicating the specific role of striatal and not hippocampal adenosinergic system in the modulation of EIMI. The potentiating effects of adenosine agonists N6-cyclohexyladenosine (CHA) and CGS-21680 on EIMI were blocked by adenosine A1- and A2-selective antagonists, 8-cyclopentyl-1,3-dipropylxanthine and 3,7-dimethyl-1-propargylxanthine, respectively, suggesting the participation of specific adenosine receptors in this functional interaction. A role for the adenosine A1 receptor in the striatal adenosinergic modulation of EIMI was favored based on the rank-order potency of adenosine agonists. IST pretreatment with pertussis toxin (PT), but not with PT beta-oligomer, nearly completely eliminated the accentuation of EIMI by CHA, further supporting the favored role of adenosine A1 receptors in EIMI. Histological and IST [3H]R-PIA distribution data confirmed that the observed behavioral effects were caused by exclusive striatal distribution of intrastriatally microinjected drugs. Data obtained suggested modulation of acute EIMI by striatal adenosine receptor-mediated mechanism(s) and the coupling of these adenosine receptor to the PT-sensitive Gi protein.

Possible central adenosinergic modulation of ethanol-induced alterations in [14C]glucose utilization in mice

The possible role of brain adenosine in acute ethanol-induced alteration in glucose utilization in the whole brain, as well as in the specific brain areas (cerebellum and brain stem), was investigated. Mice were killed 20-min postethanol, and the fresh tissue slices (300 microns) of brain and/or specific brain areas were incubated for 100 min in a 5.5 mM glucose medium in Warburg flasks using [6-(14)C]glucose as a tracer. Trapped 14CO2 was counted to estimate glucose utilization. Ethanol (2 g/kg, i.p.) markedly increased the glucose utilization in whole brain and in both motor areas of brain. Theophylline (50 mg/kg, i.p.), an adenosine antagonist, significantly reduced ethanol-induced increase in glucose utilization in whole brain, as well as in brain areas. However, adenosine agonist N6-cyclohexyladenosine (CHA; 0.1 mg/kg, i.p.) on the contrary, significantly accentuated ethanol-induced increase in glucose utilization in these tissues that was nearly completely blocked by theophylline pretreatment. Theophylline alone did not produce any significant change in glucose utilization, whereas CHA alone (in vivo and in vitro) significantly increased glucose utilization, as well as ethanol-induced increase in glucose utilization in an additive manner. Relevant supportive data were obtained by experiments in which adenosine deaminase (ADA), p-sulfophenyltheophylline (8-SPT), and CHA were administered in vitro to the slice preparations. Both ADA and 8-SPT were effective in almost completely blocking the ethanol-induced increase in glucose utilization, whereas CHA further enhanced the ethanol-induced increase in glucose utilization in an additive manner.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo effects of (-)-nicotine on ethanol-induced increase in glucose utilization in the mouse cerebellum

The purpose of this study was to investigate the possible in vivo effects of (-)-nicotine, ethanol, and an adenosine agonist N6-cyclohexyladenosine (CHA) when injected individually as well as in various combinations on glucose utilization in the fresh cerebellar slices of mice. Mice received ICV (-)-nicotine or CHA followed 5 min later by a test dose of ethanol (2 g/kg; IP). Animals were killed 20 min postethanol treatment and fresh slices (300 microns) of cerebellum were incubated in a glucose medium in Warburg flasks using 14C-glucose as a tracer. Trapped 14CO2 was counted to estimate glucose utilization. Ethanol treatment markedly accentuated glucose utilization, whereas the pretreatment with (-)-nicotine (125 and 250 ng, ICV) resulted in a significant attenuation in the ethanol-induced increase in glucose utilization. However, ICV (-)-nicotine (125 ng) alone did not produce any change in the cerebellar glucose utilization. The attenuation of ethanol-induced increase in glucose utilization by (-)-nicotine was nearly totally blocked by ICV hexamethonium, a purported nicotinic antagonist, suggesting participation of cholinergic-nicotinic receptors. The (-)-nicotine pretreatment also significantly attenuated both the ICV CHA (25 ng)-induced increase in glucose utilization and the accentuation of ethanol-induced increase in glucose utilization by CHA. The antagonistic effect of (-)-nicotine on CHA- and ethanol-induced increase in glucose utilization indicating an interaction between (-)-nicotine and ethanol and between (-)-nicotine and adenosine may suggest involvement of postreceptor (nicotinic and adenosine) mechanisms including ionic channels.

Intrastriatal Ro15-4513 functionally antagonizes ethanol-induced motor incoordination and striatal adenosinergic modulation of ethanol-induced motor incoordination in rats

To study the role of the striatum in modulating the effects of adenosine agonists and benzodiazepine inverse agonists on acute ethanol-induced motor impairment, we evaluated the effect of direct intrastriatal Ro15-4513 [0.625, 1.25 and 2.5 ng], a partial inverse agonist of benzodiazepine receptor, on ethanol-induced motor incoordination. A significant and nearly dose-dependent antagonism by Ro15-4513 was observed, which suggests involvement of the striatum in ethanol-induced motor incoordination. No effect of IST Ro15-4513 on motor incoordination induced by Na-pentobarbital (10 mg/kg, i.p.) was noted, indicating the selectivity of the antiethanol action of Ro15-4513. The IST adenosine agonist N6-cyclohexyladenosine (CHA) markedly accentuated ethanol-induced motor incoordination in a dose-related manner, suggesting a striatal adenosinergic modulation of ethanol-induced motor incoordination. The IST Ro15-4513 also significantly antagonized the accentuating effects of CHA on ethanol-induced motor incoordination. No change in normal motor coordination was observed after IST CHA or Ro15-4513 when followed by saline administration instead of ethanol. No accentuating effect by intrahippocampal CHA on ethanol-induced motor incoordination was seen, which suggests the selectivity of striatal adenosinergic modulation of ethanol-induced motor incoordination. There was no significant radioactivity present in the systemic circulation, in the CSF or in brain areas other than striatum after intrastriatal [3H]Ro15-4513 or [3H]CHA and ethanol injection. Data obtained so far support the involvement of striatum in ethanol's ataxia as well as striatal adenosinergic modulation of the central effect(s) of ethanol, possibly through Ro15-4513-sensitive mechanism(s).

Intracerebellar nicotinic-cholinergic participation in the cerebellar adenosinergic modulation of ethanol-induced motor incoordination in mice

Many epidemiological studies have suggested a high correlation between the use of tobacco and ethanol, the two most frequently abused psychoactive drugs. Recently, we reported behavioral interactions between (-)-nicotine, (-)-cotinine and ethanol within the CNS. The present report is a confirmation and an extension of that study. Using a 2 g/kg ethanol-induced motor incoordination (EIMI) as the test response, possible behavioral interactions between (-)-nicotine, (-)-cotinine and ethanol and between (-)-nicotine, (-)-cotinine and adenosine agonist + ethanol in the cerebellum were investigated. (-)-Nicotine, 0.625, 1.25 and 5 ng intracerebellarly (ICB) significantly attenuated EIMI in a dose-related manner. Likewise, ICB injection of 1.25, 2.5, and 5 ng (-)-cotinine, a major metabolite of nicotine, significantly attenuated EIMI after the same i.p. dose of ethanol as in case of (-)-nicotine but less markedly compared to (-)-nicotine. No change in normal motor coordination was observed when the highest dose of (-)-nicotine or (-)-cotinine was injected ICB followed by saline control, suggesting selectivity of their behavioral interactions with ethanol. The attenuation of EIMI by (-)-nicotine and (-)-cotinine was blocked by ICB hexamethonium (1 microgram) and trimethaphan (100 ng), the purported nicotinic-cholinergic antagonists. Finally, the ICB injection of adenosine agonists, N6-cyclohexyladenosine (CHA) or 5'-N-ethylcarboxamidoadenosine (NECA), produced marked accentuation of EIMI which was significantly antagonized by ICB (-)-nicotine and (-)-cotinine. The data obtained in the present study suggested, for the first time, a cerebellar adenosinergic-nicotinic cholinergic interaction and modulation of EIMI. The data also suggested participation of cerebellar nicotinic-cholinergic receptors in EIMI.

Central behavioral interactions between ethanol, (-)-nicotine, and (-)-cotinine in mice

A high correlation between alcohol use and smoking has long been suggested by epidemiological data. We examined the potential behavioral interactions between ethanol and nicotine using ethanol-induced motor incoordination as the test response in mice. Effect of pretreatment of various doses of (-)-nicotine, (-)-cotinine, a major metabolite of nicotine, and (+)-nicotine administered ICV on ethanol (IP)-induced motor incoordination was investigated. (-)-Nicotine (0.19, 0.38, 0.77 and, 1.54 nmoles ICV) produced significant attenuation of motor incoordination due to ethanol (2 g/kg IP) in a nearly dose-related manner which was blocked by ICV hexamethonium and trimethaphan, both purported nicotinic antagonists. (-)-Cotinine (0.35, 0.70, 1.41 nmole ICV) produced similar attenuation but was les potent than (-)-nicotine. Attenuation by (+)-nicotine (0.19, 0.38, and 0.77 nmoles ICV) was also significant but only at 0.77 nmole dose level. (+)-Nicotine-induced attenuation of motor incoordination by ethanol was antagonized by nicotinic antagonists. Data obtained suggest a central behavioral interaction between ethanol and nicotine at least through the participation of cholinergic nicotinic receptors.

Tolerance to adenosine's accentuation of ethanol-induced motor incoordination in ethanol-tolerant mice

Our previously published reports have provided data that have supported a functional correlation between ethanol-induced changes in the characteristics of adenosine receptor, adenosine uptake and release in the brain, and ethanol-induced motor incoordination. The present data demonstrated a cross-tolerance between ethanol and adenosine further supporting the hypothesis that brain adenosine modulates the motor impairing effects of ethanol. Mice that received (-)-N6-cyclohexyladenosine (CHA) [0.25 mg/kg/day, intraperitoneally (ip)] for 10 days exhibited marked attenuation (cross-tolerance) to acute ethanol-induced motor incoordination compared with chronic saline (ip) controls. The attenuation of acute ethanol-induced motor incoordination was essentially same in animals that received CHA (25 ng/5 microliters/day for 10 days) by the intracerebroventricular (icv) route as opposed to the controls that chronically received artificial cerebral spinal fluid by the same route. Similarly, tolerance was exhibited to acute CHA (0.125 mg/kg ip and 12.5 ng/5 microliters icv) by animals fed liquid ethanol (19.5 g/kg/24 hr) for 10 days compared with none in the pair-fed sucrose controls. Scatchard plots using cerebellar tissue homogenates from animals given chronic CHA or chronic ethanol indicated no change in Bmax and/or Kd values for CHA binding when compared with CHA binding in tissues from their respective controls. However, a lack of any change in the binding characteristics cannot rule out the involvement of adenosine receptors in the observed cross-tolerance between ethanol and CHA. The results may suggest desensitization of adenosine A1 receptors due to chronic CHA and ethanol as an alternate possible explanation in the development of cross-tolerance between adenosine (CHA) and ethanol.

Selective antagonism of acute ethanol-induced motor disturbances by centrally administered Ro 15-4513 in mice

Results of the present investigation demonstrated that Ro 15-4513 when given ICV selectively antagonized ethanol-induced motor disturbances at doses that did not produce motor incoordination and lacked proconvulsant activity. Ro 15-4513 in 10-, 15-, and 22-ng doses antagonized, roughly in a dose-dependent manner, ethanol-induced motor incoordination. The 10-ng dose produced an optimal effect with nearly complete antagonism within 30 min postethanol. The higher, 15 and 22 ng, doses of Ro 15-4513 antagonized, as well as probably reversed, ethanol-induced motor incoordination. The stimulation and inhibition of spontaneous motor activity by 1 and 2 g/kg IP ethanol, respectively, were also selectively antagonized by Ro 15-4513. Neither an alteration in the latency and/or duration of pentylenetetrazol-induced convulsions nor an antagonism to sodium pentobarbital-induced motor incoordination and inhibition of spontaneous motor activity by Ro 15-4513 at dose levels that showed antiethanol effects were observed. Only the 150-ng dose of Ro 15-4513, which exhibited intrinsic activity as proconvulsant, attenuated sodium pentobarbital-induced motor incoordination. When given alone at doses higher than those used in motor coordination experiments, Ro 15-4513 markedly increased spontaneous motor activity dose dependently.

Cholecystectomy with and without drainage

Thirty patients underwent cholecystectomy without drainage, and 16 matched controls cholecystectomy with drainage. The wound infection rate was lower, hospital stay shorter and overall complication rate less in undrained patients. This study suggests that surgical drainage after uncomplicated cholecystectomy is unnecessary and may be unwise.

Central adenosinergic system involvement in ethanol-induced motor incoordination in mice

To clarify if the behavioral interaction between ethanol and adenosine reported previously occur centrally or due to a peripheral hemodynamic change, the effect of i.c.v. adenosine agonists, N6-(R-phenylisopropyl)adenosine (R-PIA), N6-(S-phenylisopropyl)adenosine, 5'-(N-cyclopropyl)-carboxamidoadenosine, antagonists, theophylline and 8-p-(sulfophenyl)theophylline as well as enprofylline on ethanol-(i.p.)-induced motor incoordination was evaluated by rotorod. Adenosine agonists and antagonists dose dependently accentuated and attenuated, respectively, ethanol-induced motor incoordination, thereby suggesting a central mechanism of adenosine modulation of this effect of ethanol and confirmed our previous reports in which adenosine agonists and antagonists were given i.p. Enprofylline, a weak adenosine antagonist but potent inhibitor of cyclic AMP phosphodiesterase, did not alter ethanol's motor incoordination, further supporting involvement of brain adenosine receptor mechanism(s) in ethanol-adenosine interactions. Results from R-PIA and N6-(S-phenylisopropyl)adenosine experiments showed nearly a 40-fold greater potency of R-vs. S-diastereoisomer, suggesting predominance of adenosine A1 subtype. However, 5'-(N-cyclopropyl)-carboxamidoadenosine data indicate complexity of the mechanism(s) and point toward an additional involvement of a yet unknown subtype of adenosine A2. No effect of ethanol on blood or brain levels of [3H]R-PIA was noted and sufficient amount of the latter entered the brain to suggest adenosine receptor activation adequate to produce behavioral interaction with ethanol. There was no escape of i.c.v.-administered [3H]R-PIA from brain to the peripheral circulation ruling out a peripheral and supporting a central mechanism of ethanol-adenosine interaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Functional correlation between subclasses of brain adenosine receptor affinities and ethanol-induced motor incoordination in mice

To further investigate if the modulation of ethanol-induced motor incoordination is by brain adenosine A1 and/or A2 receptor, adenosine analogs with wide variability in their affinity for A1 and A2 subtypes were administered ICV and their effect on ethanol-induced (IP) motor incoordination was evaluated by rotorod. A dose-dependent marked accentuation of ethanol-induced motor incoordination by adenosine agonists (CHA, NECA, CPA, DCCA) tested, with nearly no effect on normal motor coordination in the absence of ethanol, was observed. There was a positive correlation between A2 affinity, A2/A1 affinity ratio but a negative correlation between A1 affinity and the potency (ED50) of adenosine agonists to accentuate ethanol-induced motor incoordination. However, with the high potency of CHA and NECA, both having significant affinity for A1 and A2 receptors, together with the well known membrane perturbation by ethanol, it seems difficult to rule out until more information becomes available the contribution of A1 receptor activation to adenosine modulation of ethanol-induced motor incoordination. The high density of high affinity A2 (A2a) in the striatum and of A1 in the cerebellum and several brain areas and the known importance of these two brain areas in the motor control, indirectly supports or at least provides a circumstantial evidence for a functional correlation between ethanol-induced motor incoordination and brain adenosine receptors.

Brain adenosine modulation of behavioral interactions between ethanol and carbamazepine in mice

The effect of the anticonvulsive drug carbamazepine on ethanol-induced motor incoordination and loss-of-righting reflex was investigated in male CD-1 mice. The results of the investigation showed that carbamazepine significantly potentiated the motor incoordinating effect of ethanol in a dose-dependent fashion. Although carbamazepine did not alter the onset time, it significantly prolonged the duration of ethanol-induced loss-of-righting reflex. Pretreatment with theophylline significantly attenuated the carbamazepine-induced potentiation of ethanol-induced motor incoordination and loss-of-righting reflex. Results from a blood ethanol study indicated no effect of carbamazepine on the clearance of ethanol. The data suggest the involvement of nonadenosinergic mechanism in carbamazepine-ethanol behavioral interactions which is responsible for the accentuating effects of carbamazepine on ethanol-induced motor incoordination and duration of loss-of-righting reflex.

Effect of acute ethanol on uptake of [3H]adenosine by rat cerebellar synaptosomes

Many classes of CNS-acting drugs have been suggested to act at least partially via inhibition of adenosine uptake. Synaptosomal uptake of [3H]adenosine and the effect of acute ethanol on it were studied in a rat brain area known to be involved in the coordination and modulation of normal motor activity, the cerebellum. Uptake of [3H]adenosine was found to be linear with time (about 40 sec) and increasing concentrations (up to 1.5 microM) of adenosine. The uptake of [3H]adenosine was inhibited by dilazep (IC50 = 2.5 x 10(-7) M) in a dose-dependent manner. Pharmacologically and/or toxicologically relevant concentrations of ethanol (2.5 to 100 mM) significantly inhibited the uptake of [3H]adenosine between 12 and 15%. Lineweaver-Burk plots indicated that both in vitro (25 mM) and in vivo (1.5 g/kg i.p.; 30 mM blood level) ethanol lowered Km as well as Vmax values for adenosine uptake to nearly the same extent. In the case of in vivo ethanol, no ethanol was present during the assay since synaptosome preparation would wash out residual ethanol. The results of the present study indicate possible membranal alterations by in vivo ethanol. It is concluded that the uptake of [3H]adenosine is inhibited by intoxicating concentrations of ethanol in vitro and by acute ethanol (1.5 g/kg) in vivo. This may partially explain the modulatory role of endogenous adenosine in ethanol-induced motor disturbances.

Effect of acute ethanol on release of endogenous adenosine from rat cerebellar synaptosomes

The effects of pharmacologically relevant concentrations of ethanol on the release of endogenous adenosine from rat cerebellar synaptosomes were investigated. Release was conducted for 5, 10, 30, or 60 s after which time the incubation medium (containing the released adenosine) was rapidly separated from the synaptosomal membranes by vacuum filtration. The adenosine content of the filtrate was measured by HPLC-fluorescence detection. Both basal and KCl-stimulated adenosine release consisted of an initial rapid phase, for the first 10 s, that was followed by a relatively slower phase. Basal endogenous adenosine release was estimated as 199 +/- 14 pmol/mg protein/5 s. Potassium (chloride) increased adenosine release from the basal level to 433 +/- 83 pmol/mg protein/5 s. Ethanol caused a dose-dependent increase of adenosine release. The interaction between dilazep and ethanol indicates that ethanol-stimulated release does not involve the dilazep-sensitive transport system. The results support previous findings that indicate that cerebellar adenosine is involved in the mediation of ethanol-induced motor disturbances in the rat.

Central nervous system effects and behavioral interactions with ethanol of centrally administered dilazep and its metabolites in mice

Dilazep (i.p.), a coronary vasodilator and an uptake inhibitor of adenosine, dose dependently potentiated acute ethanol-induced motor incoordination in mice. In view of peripheral cardiovascular depressive effects of dilazep, the effect of i.c.v. dilazep (25, 50 and 75 micrograms), and its metabolites, 1,4-bis(3-hydroxypropyl)perhydro-1,4-diazepine (BHPD) (15, 31 and 62 micrograms) and 1-[3-(3,4,5-trimethoxybenzoyloxy)propyl]perhydro-1,4-diazepine (TBPD) (62 and 125 micrograms) on ethanol-induced motor incoordination was studied. Dose-related potentiation of ethanol-induced motor incoordination was noted with dilazep and its metabolites. Whereas dilazep (i.p.) produced no apparent central nervous system (CNS) effects, by i.c.v. route, it caused CNS excitation including tonic-clonic seizures. Adenosine uptake inhibition, Ca2+ entry blockade or direct activation of adenosine receptors was ruled out as the possible mechanism of seizures because dipyridamole, verapamil or N6-(2-phenylisopropyl)-adenosine (R-PIA) administered i.c.v., while potentiating ethanol (i.p.)-induced motor incoordination did not produce seizures. The CNS excitation was minimal with BHPD and none with TBPD. Theophylline pretreatment partially blocked potentiation of ethanol-induced motor incoordination by dilazep and BHPD and not by TBPD. The data suggest dilazep-induced potentiation of ethanol-induced motor incoordination is partially due to central adenosine receptor mechanism and partly due to other yet unknown mechanism(s) and further supported our earlier reports about adenosine involvement in the CNS effects of ethanol. The data also suggest that dilazep (i.c.v.)-induced seizures are due to mechanism(s) other than adenosine uptake inhibition, Ca2+ entry blockade or direct adenosine receptor activation.

Release of endogenous glutamate from rat cerebellar synaptosomes: interactions with adenosine and ethanol

The effects of ethanol and adenosine receptor agonist R-PIA and antagonist theophylline on release of endogenous glutamate were tested in rat cerebellar synaptosomal preparation. Release was carried out for 5 to 60 sec after which time the released glutamate was separated from the synaptosomal membranes by rapid filtration. The amount of released glutamate in the filtrate was measured by an enzyme-linked fluorometric assay. Basal endogenous glutamate release was estimated as 3.7 +/- 0.3 nmol/mg protein/5 sec and was stimulated by high K+. Glutamate release consisted of an initial rapid phase for the first 10 sec that was followed by a relatively slower phase. Both Ca2+-dependent and Ca2+-independent glutamate release were observed which suggested the involvement of both neuronal and glial constituents of the synaptosomal preparation, respectively. Pharmacologically relevant concentrations of ethanol (25-100 mM) caused a trend toward a dose-dependent inhibition of glutamate release. R-PIA and theophylline inhibited and stimulated, respectively, basal release of glutamate and R-PIA-inhibited release was blocked by theophylline. Ethanol (25 mM) blocked the stimulatory effect of theophylline and the results of experiments following the inclusion of adenosine deaminase suggested the involvement of adenosine in this effect of ethanol. The results support our previous findings that suggest an involvement of cerebellar adenosine in the motor disturbing effects of acute ethanol and extend those findings by indicating that ethanol inhibits glutamate release from granule cells of the cerebellar cortex through an adenosine-sensitive mechanism.

The effects of various methods of sacrifice and of ethanol on adenosine levels in selected areas of rat brain

The effect of acute ethanol on adenosine content in four motor areas of the male Sprague-Dawley rat brain was investigated using HPLC-fluorescence detection. Since basal adenosine levels are difficult to assess due to extremely rapid turnover of adenosine, four different methods of sacrifice were also evaluated for adenosine measurement. The rank order for best results in measuring adenosine content with the various methods of sacrifice was: focused microwave irradiation greater than decapitation into liquid nitrogen greater than immersion into liquid nitrogen greater than decapitation. These differences probably reflect differences in degree of hypoxia and postmortem anoxia, factors well known to elevate adenosine, associated with the sacrifice method. Focused microwave irradiation of appropriate duration was found to be the best method of sacrifice and the results probably most closely reflect true basal adenosine levels. No significant alteration in adenosine content in any brain region examined was observed due to ethanol administration.

The biphasic effects of centrally and peripherally administered caffeine on ethanol-induced motor incoordination in mice

The possible biphasic effect of caffeine on acute ethanol-induced motor incoordination by rotorod evaluation was investigated in mice. Caffeine in various doses was administered intracerebroventricularly (i.c.v.) to mice implanted with permanent indwelling stainless steel guide cannulae and intraperitoneally (i.p.) to non-cannulated animals. A motor incoordinating test dose of ethanol, 2 g kg-1, was given i.p. in both cases. Caffeine less than 25 micrograms administered i.c.v., dose-dependently attenuated while 75 micrograms i.c.v. potentiated ethanol (i.p.)-induced motor incoordination. Similarly, caffeine less than 20 mg kg-1 given i.p., dose-dependently attenuated while 62.5 mg kg-1 potentiated ethanol (i.p.)-induced motor incoordination. The data obtained demonstrated that caffeine given either i.c.v. or i.p. exerted biphasic effects on ethanol-induced motor incoordination. The data also suggested that caffeine antagonized ethanol-induced motor micrograms i.c.v.; less than 20 mg kg-1 i.p.) caffeine is well known to display high affinity for adenosine binding sites. Therefore, the present investigation lends further support to our earlier suggestion that adenosine may be involved in the motor impairing effect of ethanol.

Mediation of acute ethanol-induced motor disturbances by cerebellar adenosine in rats

The possible involvement of brain adenosine in acute ethanol-induced motor incoordination (MI) and inhibition of spontaneous motor activity (SMA) was investigated in male Sprague-Dawley rats. Pretreatment with theophylline or 7-(2-chloroethyl)-theophylline, adenosine antagonists, markedly reduced ethanol-induced MI and inhibition of SMA during a 60 min test period compared with saline + ethanol group. On the contrary, pretreatment with (-)-N6(R-phenylisopropyl)adenosine (R-PIA), an adenosine agonist, or dilazep, an adenosine uptake blocker, markedly potentiated the ethanol-induced MI as well as inhibition of SMA in a 60 min test period compared with saline + ethanol group. No effect on motor coordination was seen when the drug pretreatment was not followed by ethanol. However, the adenosine agonists and antagonists did alter SMA when the pretreatment with these drugs was not followed by ethanol. Ethanol clearance was not altered by the drug pretreatment as blood ethanol levels were similar in all groups except for lower ethanol levels in the R-PIA-treated group. Adenosine A1 binding studies, using 3H-R-PIA as the radioligand and crude membrane preparation from cerebellar cortex, revealed an increase in Bmax with no significant change in Kd in ethanol-treated animals vs. saline control. Theophylline pretreatment prevented the increase in Bmax elicited by ethanol. Collectively, the data suggest that endogenous cerebellar adenosine may be a participating factor in ethanol-induced motor dysfunctions.

Behavioral interactions of ethanol and methylxanthines

The effect of the methylxanthines caffeine, theophylline and isobutylmethylxanthine (IBMX) on ethanol-induced ataxia and loss of righting reflex was investigated in three strains of mice. A significant potentiation of ethanol-induced ataxia was produced in all strains of mice at 20, 45 and 75 min after ethanol in mice pretreated with 62.5 mg/kg caffeine and 12.5 mg/kg IBMX. In mice pretreated with 40 mg/kg caffeine potentiation of ethanol-induced ataxia was observed only at 20 min after ethanol. Theophylline pretreatment produced no alteration in ethanol-induced ataxia. The results of methylxanthine pretreatment on ethanol-induced ataxia were similar, regardless of a shorter (10 min) or longer (75 min) pretreatment time. The methylxanthines produced no effect on motor coordination or behavior when administered separately. Although ethanol-induced loss of righting reflex was shortened by theophylline, neither caffeine nor IBMX altered the duration of loss of righting reflex. It is possible that inhibition of adenosine uptake, a known effect of the methylxanthines, may be a more likely explanation for the modulation of the behavioral effects of ethanol.

Effect of chronically administered methylxanthines on ethanol-induced motor incoordination in mice

The effect of chronic (10 days) administration of methylxanthines, caffeine, IBMX and theophylline on acute ethanol-induced motor incoordination has been investigated in the mice. In animals that received caffeine, 45 and 90 mg/kg/24 h, ethanol, 1.5 g/kg, produced motor incoordination significantly greater compared to that in the control groups. Significantly greater ethanol-induced motor incoordination was seen in animals fed IBMX, 30 and 60 mg/kg/24 h, compared to controls. Ethanol-induced increased motor incoordination in caffeine and IBMX-fed animals was also associated with significantly greater 3H-R-PIA binding in whole brains compared to tap water controls indicating an increase in brain adenosine binding sites. However neither motor incoordination nor 3H-R-PIA binding was altered in theophylline 75 and 150 mg/kg/24 h, fed animals. The increased motor incoordination associated with increased adenosine binding sites in the brains of caffeine and IBMX-fed animals suggests an involvement of central adenosine mechanisms in the motor incoordinating effect of ethanol and further supports our earlier suggestion for the role of adenosine in some of the central effects of ethanol.

Estrogen modulation of uterine adrenergic-cholinergic interaction: effects on vasoactivity and adrenergic receptors in the guinea pig

The regulation of uterine blood flow (UBF) in the guinea pig was investigated by determining the effects of steroid-catecholamine interaction on guinea pig UBF in cyclic (Day 0 = estrus) and ovariectomized (OVX)-steroid treated females. In cyclic guinea pigs, parallel elevations in uterine weight, UBF, beta and alpha receptor levels were observed during the estrus period, whereas uterine norepinephrine (NE) levels were low. In contrast, all parameters remained at low levels except NE levels during the luteal phase of the cycle which remained elevated in both normal and OVX-oil treated animals. Estrogen (E1)-treated females showed elevated uterine weights, UBF, beta, and alpha receptor levels but low uterine NE concentrations. Combined progesterone-estrogen (P2E1) treatment caused similar changes but maintained tissue NE at control levels. In the exposed uterine artery preparation, the sequential administration of acetylcholine followed by NE application induced a marked elevation in UBF in OVX, E-1-treated animals which was blocked by phentolamine (10(-6) M). This phenomena could not be demonstrated in either oil- or progesterone-treated OVX guinea pigs. In uterine membrane preparations from ovariectomized guinea pigs pretreated with either oil or progesterone, methacholine (cholinergic agonist; 10(-6) M) failed to alter the affinity of the alpha receptor for NE. However, in uterine preparations from OVX, estradiol-treated guinea pigs, methacholine significantly (P less than .05) increased the affinity of the alpha receptor for NE.(ABSTRACT TRUNCATED AT 250 WORDS)

Protective effect of zinc against ethanol toxicity in mice

Protection against the lethal effects of ethanol at 4.5 g/kg administered acutely was maximal when zinc was administered 60 min prior to ethanol. The timing of ethanol administration corresponded with elevated plasma levels of absorbed zinc. Protection was inversely related to the dose of zinc employed, as 0.5 mumol provided greater protection than 1.0 mumol, which provided greater protection than 2.0 mumol. Protection against ethanol lethality was greater if zinc was administered 60 min prior to each injection of ethanol. Acute zinc pretreatment did not alter the activity of liver alcohol dehydrogenase (ADH), nor did it alter the blood clearance of ethanol. Chronic zinc administration as ZnCl2, 100 micrograms/ml in the drinking water for 30 d, produced a 25% decrease in hepatic ADH activity, which was accompanied by a similar decrease in the intravascular clearance of ethanol.

In vivo mammalian metabolism of methylamine and methylurea and their metabolic interrelationship

The metabolism of methylamine has been investigated in the rabbit and rat, and evidence has been presented to show that the metabolism of the compound leads to the formation and excretion of methylurea, a metabolite suspected, but never conclusively shown, to exist by previous investigators. Urinary methylurea, after the administration of methyl-14C-amine, was shown to have 14C activity at both the carbonyl and methyl portions (groups) of the molecule. 14C activity in the carbonyl group of methylurea was derived from the same metabolic CO2 pool that is used in the formation of urinary urea and respiratory carbon dioxide. Administration of methyl-14C-amine led to the formation of respiratory 14CO2, as noted by various investigators, and it was shown that during a 24-hr period the ratio of specific activity (urea/respiratory CO2) approached 1, in agreement with previous data reported by Mackenzie and du Vigneaud [J. Biol. Chem. 172, 353-354 (1948)]. In order to quantitatively investigate some aspects of metabolism of methylurea, a procedure was developed for the convenient synthesis of N-methyl-14C-carbonyl-urea. In a series of experiments, the urinary urea of the animals injected with N-methyl-14C-carbonyl-urea and N-methyl-14C-urea was examined for radioactivity. Only limited amounts of 14C activity were found in the carbonyl group of urea following administration of N-methyl-14C-urea. However, after the administration of N-methyl-14C-carbonyl-urea, urinary urea contained a 200-fold excess of 14C activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Decidua-associated changes in guinea pig uterine blood flow and volume: relation to uterine norepinephrine concentrations

Changes in uterine blood flow (UBF) and uterine blood volume (UBV) during decidual tissue (DT) formation in the guinea pig were assessed at 2, 6, and 10 days postuterine trauma (PT). Uterine weight increased steadily between days 2 and 10 PT in DT-bearing animals as compared with the constant uterine weights observed in controls. Both UBF and UBV levels were elevated between days 2 and 10 PT in DT-bearing animals as compared with controls with the vascular changes being histologically related to the progressive stromal differentiation. Uterine norepnephrine (NE) levels were significantly (P less than or equal to 0.05-0.01) depressed in the hyperemic, DT-bearing uteri as compared with controls. These results indicate that the uterine hyperemia associated with DT formation in the guinea pig involves a sustained increase in uterine vascular volume as well as vascular perfusion rate under conditions of depressed uterine NE levels. These events are intimately associated with the support of stromal differentiation in the guinea pig.

The enzymatic systems involved in the mammalian metabolism of methylamine

The metabolism of methylamine has been investigated in the rat in order to elucidate the role of monoamine oxidase (MAO; EC 1.4.3.4) and intestinal bacteria in the metabolism of the compound. In a series of experiments in which short- and long-acting inhibitors of MAO were administered either alone or in combination prior to methyl-[14C]amine hydrochloride injection, the excretion of radioactivity in the expired air and the urine was examined to indirectly assess the role of MAO in the metabolism of methylamine. The data presented provide indirect evidence to demonstrate that the effect of iproniazid, an inhibitor of methylamine oxidation, is mediated through enzyme systems separate from MAO systems which have been invoked as major contributors to metabolism of methylamine by other investigators. The bacterial oxidation of methylamine in the intestine plays a minor role in the overall metabolism of the compound.

Effect of chronic ethanol administration on arterial baroreceptor function and pressor and depressor responsiveness in rats

The effect of chronic ethanol administration on arterial baroreflexes was investigated in rats. Comparison of the results with those obtained from rats kept on an isocaloric control diet revealed that chronic ethanol had a differential action on baroreflex sensitivity (BS). The BS after evoked graded rises in arterial pressure was inhibited significantly whereas that tested after an evoked fall in arterial pressure was augmented significantly in chronic ethanol rats. These changes in BS were not secondary to changes in blood pressure as resting arterial pressure was similar in both groups. However, the heart rate was slightly, but significantly lower in the ethanol group. Challenging isocaloric control and chronic ethanol rats with an acute dose of 0.5 g/kg of ethanol produced nonsignificant changes in BS when evoked changes in blood pressure were both pressor and depressor. A dose of 3 g/kg of ethanol decreased the BS tested after phenylephrine-evoked rises in pressure in both groups; however, the percentage of inhibition of BS was greater in the isocaloric control group. The pressor responsiveness to phenylephrine was reduced slightly in chronic ethanol-treated rats, in contrast to that evoked by angiotensin II which was augmented slightly as compared to the control group. There was no significant difference in the depressor responsiveness to nitroprusside. After injection of acute doses of 0.5 and 3 g/kg of ethanol, the dose-response curves to phenylephrine were shifted to the right in a dose-related fashion in both groups, whereas the angiotensin II and nitroprusside dose-response curve remained unchanged after 0.5 g/kg of ethanol in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

GABA mediation of the central effects of acute and chronic ethanol in mice

In acute ethanol studies aminooxyacetic acid (AOAA) alone produced marked hypothermia although a test dose of ethanol was able to produce a further drop in body temperature in AOAA treated mice. Even though tolerance to ethanol-induced hypothermia was present in ethanol-dependent mice, AOAA administration was able to produce a further decrease in body temperature. Bicuculline potentiated ethanol-induced hypothermia in the acute studies but the tolerance to hypothermia which had developed in ethanol-dependent mice prevented the bicuculline-induced potentiation of ethanol hypothermia. AOAA markedly potentiated acute ethanol-induced motor incoordination whereas bicuculline had no effect. Although partial tolerance had developed to ethanol-induced motor incoordination in dependent mice, AOAA potentiated, whereas a lower dose of bicuculline antagonized, motor incoordination. In the acute studies ethanol had a biphasic effect on AOAA-induced GABA accumulation in the hypothalamus and corpus striatum: low doses prevented and a slightly higher dose was without effect on GABA accumulation. Ethanol-dependent mice were unable to respond to an AOAA-induced increase in GABA accumulation although basal levels of GABA were unaffected by chronic ethanol ingestion. The results show that brain GABA or GABA-mediated central mechanisms may be involved in the mediation of ethanol-induced motor incoordination but not hypothermia.

Striatal and hypothalamic neurotransmitter changes during ethanol withdrawal in mice

The alterations in striatal and hypothalamic GABA, DA and its metabolites DOPAC and HVA, and in hypothalamic NE were investigated immediately after ethanol removal and during the withdrawal phase following 10 or 30 days of chronic ethanol administration. After 10 days of ethanol, GABA levels were increased immediately after ethanol removal in both the corpus striatum and the hypothalamus. The concentration of striatal DA was increased at days 2 and 3 of withdrawal and was unchanged at any other time. There was no change in the concentration of DOPAC and HVA in the hypothalamus at any time during withdrawal. Striatal DOPAC and HVA levels were increased only at day 7 of withdrawal after 10 and 30 days of ethanol feeding which was associated with a return of striatal DA to control levels. The concentration of NE in the hypothalamus was increased at days 1, 2 and 7 of withdrawal. After 30 days of ethanol, striatal GABA was increased only at day 7 of withdrawal whereas striatal DA levels were only increased at days 2 and 3 of withdrawal. Hypothalamic NE was markedly increased at days 2, 3 and 7 of withdrawal. The increase in DA concentration associated with no change in DOPA accumulation following inhibition of DOPA decarboxylase and a decrease in the striatal disappearance of DA after alphamethylparatyrosine (alpha-MT) suggests the presence of a hypodopaminergic state. On the other hand an increase in the disappearance of NE in the hypothalamus after alpha-MT suggests an increased NE turnover and a hyperadrenergic state during withdrawal. The increase in striatal GABA at day 7 of withdrawal after 30 days of ethanol may be a rebound phenomenon and may reflect the presence of a hypogabaergic state which has been shown to occur during ethanol withdrawal.

Regulation of estrogen-induced uterine hyperemia and contractility in the guinea pig: cholinergic modulation of an alpha-adrenergic response

The effects of estradiol (1 microgram: E-1) treatment on uterine hyperemia and uterine sensitivity to various biogenic compounds were evaluated in ovariectomized (OVX) animals treated with either sesame oil or E-1 for 3 days. The E-1 treatments induced significant elevations in uterine weight, blood flow, and alpha- and beta-receptor numbers as compared with oil-treated controls. In contrast, uterine norepinephrine (NE) levels were reduced in E-1-treated, OVX guinea pigs as compared with oil-treated controls. Uterine sensitivity and responsivity to NE (10(-6) M) and acetylcholine (ACH: 10(-8) M) were either comparable to, or enhanced, in E-1-treated animals as compared with controls. In particular, combined ACH-NE treatment induced a dramatic increase in contraction force in E-1-treated uteri as compared with uteri from oil-treated animals. The use of specific adrenergic alpha- (phentolamine: 10(-6) M) or beta- (propranolol: 10(-6) M) receptor blocking agents indicated that the estrogenic response was mediated via the alpha-adrenergic receptor complex. Since atropine (10(-8) M) effectively blocked the cholinergic accentuation of this uterine response, it is suggested that a cholinergic priming, or beta-receptor block, is necessary for the full expression of the alpha-adrenergic-mediated, estrogenic response in the guinea pig. The estrogen-associated increase in available alpha- and beta-receptors and depressed tissue NE levels probably account for both the hyperemic response and enhanced tissue sensitivity to biogenic compounds in the guinea pig.

Possible role of adenosine in the CNS effects of ethanol

The ability of adenosine to modify the CNS effects of acute and chronic ethanol was studied by using theophylline, an adenosine antagonist, and dipyridamole, a blocker of adenosine reuptake. We also studied the binding characteristics of adenosine using crude membranes of whole brain. Theophylline pretreatment prior to acute ethanol administration markedly reduced the duration of ethanol-induced sleep and similarly decreased the intensity and duration of motor incoordination. In chronic ethanol treated mice the effect of theophylline on ethanol-induced hypnosis and motor incoordination was similar to the acute experiment. Dipyridamole markedly prolonged the duration of ethanol-induced hypnosis and potentiated the motor incoordination produced by acute ethanol. However, in chronic ethanol treated mice dipyridamole was not able to potentiate the motor incoordinating effect of ethanol although it was able to prolong ethanol hypnosis similar to the results obtained in the acute ethanol study. Neither drug had any effect on ethanol-induced hypothermia, in either the acute or chronic studies. After 10 days of ethanol ingestion the adenosine dissociation constant was unchanged whereas the number of brain adenosine receptors was increased 28% although the increase did not reach statistical significance. The number of adenosine receptors was reduced 40% at 24 and 48 h after withdrawal and returned to prewithdrawal levels at 72 h. The dissociation constant was reduced at 24 and 48 h but by 72 h had returned to prewithdrawal levels. The marked changes in adenosine binding characteristics as well as the modification of some CNS effects of ethanol by drugs which influence either adenosine binding to its receptor or the availability of adenosine suggests that adenosine may be involved in the expression of some of the CNS effects of ethanol.

Ophthalmomyiasis caused by the sheep nasal bot, Oestrus ovis (Oestridae) larvae, in the Benghazi area of Eastern Libya

In a two-year study, from January 1977 to December 1978, 80 human cases of ophthalmomyiasis were recorded at the Benghazi Central Eye Clinic. Infections were due to larvae of the sheep nasal bot, Ostrus ovis. The annual incidence was estimated to be 10 per 100,000 population, with most of the cases occurring amongst males during the months of May, June and July. A typical case history is described to illustrate the clinical features and the treatment used.

The anticonvulsant and CNS activity of N-butyryl-N-butylurea in mice

As a further extension of our studies related to CNS activity of substituted butylureas, a number of derivatives of butylurea were synthesized. Among these a derivative of n-butylurea, N-butyryl-N-butylurea (NBNB) was prepared by acylation of n-butylurea with butyryl chloride in pyridine. The compound was found to possess considerable sedative-hypnotic action. Sleeping time of pentobarbital and barbital was significantly potentiated by NBNB. The compound also exhibited moderate anti-tremorine action and produced significant reduction in the activity ratio for Treadmill experiments. Significant anticonvulsive activity of NBNB was observed against strychnine, pentetrazole and supramaximal electroshock-induced convulsions. In addition to protection against tonic convulsions, the animals were also protected against strychnine and pentetrazole lethality.