A canine model for determination of the therapeutic index of cytokine inhibitors

Using tumor necrosis factor (TNF) inhibition in dog blood as a measure of efficacy, and canine emesis as a measure of toxicity, we were able to assign a therapeutic index to rolipram, a prototypic anti-inflammatory compound. Because both assays were performed in the same species, the ambiguities associated with comparing the physiologic effects of drugs on various species was avoided. Rolipram, a standard phosphodiesterase type IV inhibitor, was a prototypic test compound characterized by a number of cardiovascular and central nervous system side effects, as well as its in vitro and in vivo inhibition of TNF. Initial experiments with canine whole blood incubated with lipopolysaccharide resulted in nanogram-per-milliliter concentrations of TNF that could be significantly reduced by in vitro addition of a 0.03 microM concentration of rolipram. Because rolipram inhibited canine TNF production in vitro, a protocol was devised in which TNF inhibitory activity was measured in a series of blood samples from dogs infused with increasingly high doses of rolipram. This yielded the efficacy half of the therapeutic index, whereas the emetogenic dose represented the side effect portion of the index. Rolipram was infused stepwise into conscious dogs at gradually increasing doses. The infusion was stopped when vomiting occurred, and the cumulative dose was reported as the emetic dose. Rolipram caused emesis in dogs at a cumulative dose of 0.1 mg/kg. At each dose of rolipram, blood was collected. The whole blood was incubated in vitro with lipopolysaccharide to induce TNF production, which in turn was quantified by the L929 bio-assay. Theoretically, if the rolipram infusion raised blood values high enough, the rolipram in whole blood would inhibit TNF production and be reflected by a lack of TNF activity in the L929 assay. In this assay system, rolipram's 50% effective dose in the TNF assay was always at least 33-fold lower than its emetic dose of 0.1 mg/kg. This gave rolipram a therapeutic index of at least 33:1 (0.003 versus 0.1 mg/kg) on the basis of its activity in a canine efficacy model (TNF inhibition) and a toxicity model (emesis induction). Experimental compounds were tested for their emetic dose as well as TNF 50% effective dose, with the goal of obtaining a therapeutic index better than that of rolipram. Thus the coupling of cytokine activity with overt toxicity was used to arrive at the therapeutic index of a compound. The therapeutic index was used to rank compounds as to their efficacy/toxicity profile. This ranking was used to eliminate several anti-inflammatory compounds that had a therapeutic index less than that of rolipram.

1-Methyl-2-pyrrolidone (NMP): reproductive and developmental toxicity study by inhalation in the rat

A two-generation reproduction study with a developmental toxicity component was conducted. For the reproduction phase, male and female rats inhaled 0, 10, 51, or 116 ppm NMP daily for 6 hr/day, 7 days/week from 34 days of age to the end of the mating period for the males (100 exposure days) and till weaning for the females (about 143 exposure days, but interrupted from Day 20 of gestation to Day 4 Postpartum). On Day 70 postpartum, one male and one female selected from each litter later mated with newly obtained, nonexposed adults of the opposite sex to produce an F2 generation. For the developmental phase, rats of both sexes inhaled 0 or 116 ppm NMP as outlined above, but euthanization of the females occurred on Day 21 of gestation followed by fetal examination for structural alterations. The indices of reproductive performance for the NMP-exposed rats did not differ significantly from those obtained for the control rats. Rats exposed to 116 ppm had a detectable decrease in response to sound. No other signs of NMP-related toxicity were detected among the parental rats. An exposure-related but slight decrease in fetal weight was detected only among the F1 offspring whose parents both inhaled NMP at 116 ppm. This slight effect also appeared at birth among the pups of the reproductive phase where it persisted till 21 days after birth when NMP inhalation by the mother ceased. Thereafter, the body weight of the offspring was comparable to the control values. No detectable or developmental effects appeared in the 10 or 51 ppm groups.

Male reproductive toxicity study of nefiracetam in rats

Sprague-Dawley male rats were administered nefiracetam orally at daily doses of 500 and 1500 mg/kg/day for 4 or 9 weeks. Although the copulation index was not affected by nefiracetam treatment, the fertility index was extremely low in the 1500 mg/kg/day group for both treatment periods. This high dose group consistently exhibited decreased testicular weights. Epididymal and prostate weights were also reduced in the 1500 mg/kg/day group after both 4- and 9-week treatments and in the 500 mg/kg/day group after the 9-week treatment. Severe degenerative changes such as degeneration of germ cells, loss of germ cells and atrophy of seminiferous tubules were observed in all rats of the 1500 mg/kg/day groups after both 4 and 9 weeks of treatment. Retention of spermatids in stage IX, X and XI seminiferous tubules was also noted after the 4- and 9-week treatments at 500 mg/kg/day. The testicular sperm head counts were markedly decreased following the 4- and 9-week treatments at 1500 mg/kg/day, and mildly reduced after the 4-weeks treatment at 500 mg/kg/day. From these results it is concluded that histopathological examination and the testicular sperm head count method are highly useful for detecting testicular toxicity and that testicular lesions caused by nefiracetam can be detected after 4 weeks of exposure.

Glucoprotamine--a new antimicrobial substance

Glucoprotamine is the conversion product of L-glutamic acid and cocopropylene-1.3-diamine. The wax-like substance is non-volatile and easily dissolved in water. The microbiological activity was examined in the inhibition test, suspension test and practical surface test under practical conditions. The action spectrum covers bacteria including mycobacteria, fungi and viruses. The active substance is classified as harmful and displays no sensitizing or mutagenic characteristics. According to the international test methods for total degradability, the degradability of glucoprotamine is good. On account of its broad action spectrum and its good compatibility with man and the environment, glucoprotamine is a highly interesting new antimicrobial substance.

Effects of prenatal exposure to N-methylpyrrolidone on postnatal development and behavior in rats

Pregnant rats (Mol:WIST) were exposed to 150 ppm N-methylpyrrolidone for 6 hours per day on gestation days 7-20. The dose level was selected so as not to induce maternal toxicity or decrease viability of offspring. In the preweaning period, the exposed offspring had a lower body weight and their physical development was delayed. Neurobehavioral evaluation of the male pups revealed no effects on basal functions of the central nervous system. The animals appeared normal and motor function (rotarod), activity level (open field), and performance in learning tasks with a low grade of complexity were similar in the two groups. However, in more difficult tasks such as the reversal procedure in Morris water maze and operant delayed spatial alternation (Skinner boxes), performance was impaired in exposed offspring.

Single dose toxicity study of the new cognition-enhancing agent nefiracetam in mice, rats and dogs

Single oral dose toxicity of nefiracetam (N-(2,6-dimethylphenyl)-2-(2-oxo- 1-pyrrolidinyl) acetamide, DM-9384, CAS 77191-36-7), a new cognition-enhancing agent, was examined in ddY mice, SD rats and beagle dogs. The LD50 values of nefiracetam were 2005 mg/kg for male mice and 1940 mg/kg for female mice, 1182 mg/kg for male rats and 1408 mg/kg for female rats and more than 500 mg/kg for beagle dogs. Common toxic signs in all species were a decrease in locomotor activity, lying on the side or back and loss of righting reflex, considered to be caused by depression of the central nervous system. Pathologically, no remarkable change associated with nefiracetam administration was observed in any species. In addition, toxicities of the decomposition product (D-2) and by-products (Bis, 3-Me and 4-Me) of nefiracetam were examined by oral administration, and of the metabolites (M-3 and M-11) by intravenous injection in male ddY mice. LD50 values of the 3-Me and 4-Me forms were 1399 and 1534 mg/kg, respectively. Clinical signs in mice treated with these by-products were similar to those caused by nefiracetam. The other compounds induced no toxic signs or death up to the highest dose (2000 mg/kg) used.

Fifty-two-week oral toxicity study of the new cognition-enhancing agent nefiracetam in dogs

A 52-week toxicity study by oral administration (capsule) was performed in beagle dogs with nefiracetam (N-(2,6-dimethylphenyl)-2-(2- oxo-1-pyrrolidinyl) acetamide, DM-9384, CAS 77191-36-7), a new cognition-enhancing agent, as a part of a safety evaluation program. Dosages of 0 (control), 10, 30 and 90 mg/kg/d were selected for this study. Treatment-related findings were confined to the 90 mg/kg/d level and indicated the kidney and the testis as the main target organs for toxicity. Signs of systemic toxicity, as indicated by the laboratory investigations, were not apparent until the second half of the study and included the principal findings of higher urea nitrogen, and creatinine, with higher urinary volumes and corresponding lower specific gravity, osmolarity and protein values. The microscopic pathology examination showed various changes at the renal papilla, collecting ducts, and medullary and cortical scarring. This examination also revealed decreased spermatogenesis in the testes, with associated decreased numbers/absence of spermatozoa in the epididymides. At the 30 mg/kg/d level, the minor microscopic pathology changes seen in the kidneys of one male animal were considered to be of equivocal toxicological importance. There were no treatment-related findings at the low dosage level (10 mg/kg/d) and, therefore, this level was considered as the non-toxic effect level of nefiracetam.

Reproductive toxicity studies of the new cognition-enhancing agent nefiracetam in rats and rabbits

The reproductive toxicity of nefiracetam (N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl) acetamide, DM-9384, CAS 77191-36-7) was investigated in rats and rabbits. Nefiracetam was administered orally for 9 weeks or more until successful copulation to male rats at doses of up to 480 mg/kg/d. Female rats were treated with nefiracetam at the same doses for more than 2 weeks prior to and in the early stages of pregnancy. No adverse effects on fertility were noted at any dose level. Nefiracetam elicited no evidence of teratogenicity when administered during the fetal organogenesis period to pregnant rats at doses of up to 1000 mg/kg/d, or to pregnant rabbits at doses of up to 270 mg/kg/d. Rat fetuses in the 1000 mg/kg group exhibited decreased body weights, delayed ossification and an increased incidence of skeletal variations such as cervical ribs and shortening of the 13th ribs. Decreased body weight gain and decreased food intake were also noted in rat dams of the 1000 mg/kg group. Nefiracetam showed no adverse effects on postnatal development, behavior or reproductive performance of rat offspring, except for decreased body weight gain in the 1000 mg/kg group. Rabbit fetuses in the 270 mg/kg group exhibited increased skeletal variations, mainly presence of the 13th ribs. Decreased body weight gain and decreased food intake were also noted in rabbit dams of the 270 mg/kg group. In a perinatal and postnatal toxicity study in rats using doses of up to 500 mg/kg, decreased food intakes were noted in dams of the 500 mg/kg group.(ABSTRACT TRUNCATED AT 250 WORDS)

Thirteen-week oral toxicity study of the new cognition-enhancing agent nefiracetam in rats

Thirteen-week toxicity of nefiracetam (N-(2,6-dimethylphenyl)-2-(2-oxo-1- pyrrolidinyl) acetamide, DM-9384, CAS 77191-36-7) was examined in rats by oral administration of 30, 120, or 480 mg/kg. Rats receiving 480 mg/kg showed salivation, prone position, increased water consumption, increased levels of serum total cholesterol, total protein, albumin and total bilirubin, increased liver weight and hypertrophy of liver cells. This hypertrophy of hepatocytes with increased liver weight was also observed in males at 120 mg/kg. The non-toxic dose of nefiracetam under the present experimental conditions was therefore determined as 30 mg/kg.

Drug dependence study of the new cognition-enhancing agent nefiracetam in rats

The new cognition-enhancing agent nefiracetam (N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl) acetamide, DM-9384, CAS 77191-36-7) was assessed for dependence liability in rats using the DAF (drug admixed food) method and an intravenous self-administration system. In the physical dependence test, nefiracetam and codeine phosphate were administered to rats mixed with food for 43 days in a gradually increasing dosage schedule, followed by feeding a drug-free normal diet to detect signs of withdrawal. After the withdrawal, rats in the nefiracetam treated groups showed no withdrawal symptoms (e.g. body weight loss) and exhibited greater body weight gains than control. On the other hand, rats in the codeine phosphate treated group showed overt withdrawal symptoms (e. g. soft stool, diarrhea, vocalization) and a significant body weight loss, suggesting development of physical dependence on the drug. It was concluded that nefiracetam did not possess physical dependence liability in rats. In the reinforcement liability test, through an indwelling cannula implanted into the right jugular vein rats were allowed to self-administer nefiracetam, morphine hydrochloride or pentobarbital for 14 days. Saline was administered to negative control animals for the same period. The daily frequency of self-administration increased progressively with time in rats of the morphine hydrochloride and pentobarbital groups. In the nefiracetam groups, it remained comparable to or was even lower than that in the saline control group. When compared with the saline control, the group mean frequency of self-administration showed a tendency to be small for nefiracetam, whereas the morphine hydrochloride and pentobarbital showed greater frequencies.(ABSTRACT TRUNCATED AT 250 WORDS)

Oncogenicity studies of the cognition-enhancing agent nefiracetam in mice and rats

Oncogenicity studies of nefiracetam (N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl)acetamide, DM-9384, CAS 77191-36-7), a new cognition-enhancing agent, were carried out in male and female mice and rats. The compound was administered in diet for 104 weeks at dosage levels of 30, 90 and 270 mg/kg/d for mice and of 200, 600 and 1800 ppm for rats. The administration of nefiracetam produced no effects on survival, appearance or behavior. Body weights of the high dose male mice and rats were occasionally significantly decreased when compared to the controls. When calculated on a g/animal/d basis, food consumption was sometimes decreased for these male groups. At necropsy, there was no evidence of treatment related changes, nor were these seen on histopathological examination. All microscopic changes seen in mice and rats were of the usual type commonly occurring in untreated aged B6C3F1 mice and F344 rats. In conclusion, the administration of nefiracetam for 24 months to B6C3F1 mice and F344/DuCrj rats produced only slight effects on body weight in the high dose males with a no-effect level of 90 mg/kg/d for mice or 600 ppm for rats. There was no evidence of an oncogenic effect of nefiracetam.

Mutagenicity study of the new cognition-enhancing agent nefiracetam

A new cognition-enhancing agent, nefiracetam (N-(2,6-dimethylphenyl)-2- (2-oxo-1-pyrrolidinyl) acetamide, DM-9384, CAS 77191-36-7) was studied for mutagenicity by using the following short-term in vitro and in vivo tests: 1. reverse mutation test (Ames method) on S. typhimurium and E. coli, 2. cytogenetic test on Chinese hamster cells, and 3. mouse micronucleus test. In the cytogenetic study, nefiracetam caused a slight but significant increase of chromosomal aberration at the highest dose in the 48 h treatment group, but no mutagenicity was observed with the same indicator in the in vivo micronucleus test. Furthermore, nefiracetam did not show any positive response in the reverse mutation test. These results suggest that nefiracetam has no biologically significant respectively relevant mutagenic potential.

Thirteen-week oral toxicity study of the new cognition-enhancing agent nefiracetam in dogs

The 13-week oral toxicity of nefiracetam (N-(2,6-dimethylphenyl)-2-(2-oxo- 1-pyrrolidinyl) acetamide, DM-9384, CAS 77191-36-7), a new cognition-enhancing agent, was investigated in Beagle dogs of both sexes. No change was observed in the 20 mg/kg group. Hypospermatogenesis and slightly increased deposition of hemosiderin in the spleen were seen in male dogs treated with 60 mg/kg or more. Dosing at 180 mg/kg induced a decrease in food consumption, increases in urinary volume and urinary protein, and renal papillary necrosis in both male and female dogs. The non-toxic dose was 20 mg/kg under these experimental conditions.

Fifty-two-week oral toxicity study of the new cognition-enhancing agent nefiracetam in rats

A 52-week toxicity study by oral gavage administration was performed in Sprague-Dawley rats with nefiracetam (N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl) acetamide, DM-9384, CAS 77191-36-7), a new cognition-enhancing agent, as a part of a safety evaluation program. Dosages of 0 (control), 10, 30, 100 and 300 mg/kg/d were selected for this study. Treatment-related findings were confined to the 300 mg/kg/d level and, to a lesser extent, the 100 and 30 mg/kg/d levels, with the investigations indicating the kidney as the main target organ for toxicity. The microscopic pathology examination of this organ showed papillary epithelial hyperplasia and/or collecting duct epithelial hyperplasia, with cortical scarring and occasional mineralisation in the papilla. Histopathological changes in the liver, centrilobullar hepatocyte enlargement (accompanied by fine vacuolation) and foci/areas of eosinophilic hepatocytes were considered to reflect the induction of drug-metabolising enzymes in the liver. Other tissues showing treatment-related findings included the salivary glands, urinary bladder, spleen, pancreas and adrenals. Additionally, other notable findings included (in the high dosage males only) a decline in body weight (from week 34), lower erythrocytic characteristics and slightly higher plasma urea nitrogen and alkaline phosphatase values. The results in this study, therefore, indicated that the non-toxic effect level was 10 mg/kg/d of nefiracetam.

Synthesis and CLOGP correlation of imidooxy anticonvulsants

Continuing structure-activity studies on the anticonvulsant activity of analogs of N-(benzyloxy)-2-azaspiro[4.4]nonane-1,3-dione (2a), which displayed anti-electroshock seizure (MES) activity and a protective index (TD50/ED50) of > 4.5 are reported. An in-depth analysis of this moiety was studied employing the Topliss structure activity and the Craig plot analytical approaches as well as a semiempirical method. CLOG P analysis was also applied to this series after experimentally determining the NOR fragment. All compounds were minimized and these physicochemical parameters correlated to anticonvulsant activity. Several interesting substituted benzyloxy compounds emerged from this study: the 2',4'-dichloro (2b), 4'-(trifluoromethyl) (2c), 2'-bromo (2d), 3'-chloro (2o), 2'-chloro (2r), 2'-fluoro (2p), and 3'-fluoro (2w) analogs, all of which had comparable, or better activity than the parent unsubstituted analog (2a). X-ray crystal analysis of the active 2a versus inactive N-benzyl-2-azaspiro[4.4]nonane-1,3-dione (10) is discussed.

The use of the Computerized Neuropsychological Test Battery (CNTB) in an efficacy and safety trial of BMY 21,502 in Alzheimer's disease

BMY 21,502 is a nootropic which protects memory and enhances long-term potentiation according to preclinical findings. Alzheimer's disease (AD) patients who were diagnosed by DSM-III-R and NINCDS-ADRDA criteria were enrolled in a 12-week double-blind investigation of BMY 21,502 vs. placebo at 300 mg tid. The study design included a 1-week placebo lead-in and a 4-week placebo washout in addition to the 12-week double-blind treatment period. Efficacy was assessed with the Alzheimer's Disease Assessment Scale (ADAS) and the Computerized Neuropsychological Test Battery (CNTB) at weeks 4, 8, 12, and 16. Clinical Global Impression (CGI) assessments were also performed biweekly. Sixty-nine patients (28M, 41F; mean age 72 years, range 54 to 92 years) were enrolled in the study. Baseline Mini-Mental Status Examination (MMSE) scores ranged from 16 to 26 (mean 23.5) in patients on active drug (n = 34), and from 15 to 26 (mean 22.5) in placebo patients (n = 35). Baseline efficacy scores were comparable for drug and placebo patients (p > 0.05). Twelve (35%) patients who received BMY 21,502 withdrew from the study, 8 (24%) due to adverse events. Three (9%) patients who received placebo withdrew from the study, all due to adverse events. Patients on active drug who were valid for analysis of efficacy (n = 22) showed a mean decrease in ADAS of -1.5 at week 12, vs. a mean change of -0.5 in patients who received placebo (n = 32), although there was no significant difference between the two (p > 0.05). Correlations between the CNTB summary scores and ADAS cognitive subscores were, nevertheless, highly significant at baseline (r = -0.83, p = 0.0001) and week 12 (r = -0.83, p = 0.0001). Correlations between the word list learning, spatial, and naming subtests of the ADAS and CNTB were also highly significant (p = 0.0001). Although modest, the findings for active drug vs. placebo response in this study suggest that BMY 21,502 should be further investigated, with a larger study population, in order to fully determine the compound's potential efficacy.

The acute toxicity and in vivo antitumour activity against L1210 leukemia of triphenyltin 3,5-diisopropylsalicylate, bis (di-n-butyl-(s)-2-pyrrolidone-5-carboxylato)tin oxide and di-n-butyltin bis(3-amino-4-methylbenzoate)

Triphenyltin 3,5-di-isopropylsalicylate, compound 1, is characterized by a maximum tolerated dose (MTD) of 20 mg/kg. Bis[di-n-butyl(2-pyrrolidone-5-carboxylato)tin] oxide, compound 2, and (di-n-butyltin bis(3-amino-4-methyl-benzoate), compound 3, exhibit similar acute toxicities (MTD = 8 mg/kg) despite their lower in vitro activity, as compared to compound 1, against the two human tumor cell lines MCF-7 and WiDr. All three are inactive in vivo against L1210 leukemia in mice.

[Synthesis and biological activity of 1,5-diaryl-3-alkylamino-4-carboxymethyl-2,5-dihydropyrrol-2-ones and 1,5-diaryl-4-carboxymethyltetrahydropyrrol-2,3-diones]

By interaction of alpha-ketoglutaric acid with Schiff bases 1,5-diaryl-3-arylamino-4-carboxymethyl-2,5-dihydropyrrol-2-ones 1 were obtained. Hydrolysis of the latter, carried out with hydrochloride acid gave 1,5-diaryl-3-hydroxy-4-carboxymethyl-2,5-dihydropyrrol-2-ones 2. On treatment of 2 with aryl-amines the starting compounds 1 were yielded. All compounds were tested for their antiphlogistic activity.

1-Methyl-2-pyrrolidinone (NMP) does not induce structural and numerical chromosomal aberrations in vivo

1-Methyl-2-pyrrolidinone induces aneuploidy in yeast, but only under special treatment conditions. Other genotoxic effects have not been found in vitro, and in vivo no data are available in the literature. Therefore, NMP was investigated in the mouse micronucleus test and the Chinese hamster bone marrow test for structural and numerical chromosomal aberrations. These tests can detect both types of alterations as demonstrated by appropriate positive control substances (cyclophosphamide, vincristine sulfate and benomyl). NMP at single oral doses up to 3800 mg/kg body weight (approximately 80% of the LD50) did not lead to an increase either in micronucleated erythrocytes or in structural or numerical chromosomal aberrations when bone marrow was sampled 16, 24 and 48 h after treatment in the micronucleus test or after 24 and 48 h for karyotype analysis.

Further confirmation of the role of adenyl cyclase and of cAMP-dependent protein kinase in primary afferent hyperalgesia

Recent evidence has suggested that cAMP plays a role as a second messenger in the decrease in nociceptive threshold (or hyperalgesia) produced by agents acting on primary afferent terminals. In support of this hypothesis we report that intradermal injection of a direct activator of adenyl cyclase, forskolin, produces a dose-dependent hyperalgesia in the rat. The duration of this hyperalgesia was prolonged by the phosphodiesterase inhibitors, isobutylmethylxanthine and rolipram. Forskolin hyperalgesia was antagonized by the Rp isomer of cyclic adenosine-3'5'-monophosphothioate, an analog of cAMP that prevents the phosphorylation of the cAMP protein kinase. The Rp isomer of cyclic adenosine-3'5'-monophosphothioate also inhibited the hyperalgesia induced by a membrane-permeable analogue of cAMP, 8-bromocyclic adenosine monophosphate, as well as the hyperalgesia induced by agents that are presumed to act directly on primary afferent nociceptors: prostaglandin E2, prostaglandin I2, (8R,15S)-dihydroxyicosa(5E-9,11,13Z)tetraenoic acid; and the adenosine A2-agonist 2-phenylaminoadenosine. Although the cAMP second messenger system contributes to primary afferent hyperalgesia, we found no evidence for a contribution of protein kinase C. Thus, hyperalgesia induced by prostaglandin E2, prostacyclin (prostaglandin I2), (8R,15S)-dihydroxyicosa(5E-9,11,13Z)tetraenoic acid, the adenosine A2-agonist 2-phenylaminoadenosine, 8-bromocyclic adenosine monophosphate and the direct activator of adenyl cyclase, forskolin, were not significantly attenuated by the selective inhibition of protein kinase C by the 19-31 fragment of protein kinase C. Two other inhibitors of protein kinase C, sphingosine and staurosporine, also failed to attenuate prostaglandin E2-induced hyperalgesia.

Acute toxicity and skin irritation of pyrrolidone derivatives as transdermal penetration enhancer

We investigated preliminary acute toxicity and primary skin irritation of nine pyrrolidone derivatives which had been previously developed as transdermal penetration enhancers. The acute toxicity was observed at a dose of 500 mg/kg after intraperitoneal administration in mice. Their primary skin irritations were examined with rabbit dorsal skin. 1-Lauryl-2-pyrrolidone induced the most severe irritation among the derivatives. Pyrrolidone derivatives having methyl group and methyloxycarbonyl group caused little irritation. The primary irritation indices of pyrrolidone derivatives were not relative to their accumulations in the skin but to their enhancing effects. In conclusion, 1-hexyl-4-methyloxycarbonyl- and 1-lauryl-4-methyloxycarbonyl-2-pyrrolidone are suggested to be adequate enhancers, judging from the balance of their enhancing activity and irritation.

Chronic intrastriatal L-pyroglutamate: neuropathology and neuron sparing like Huntington's disease

Continuous injection of L-pyroglutamate (L-PGA) into the rat striatum induces a lesion with three regions: a necrotic core, a rim of pyknotic cells, and a peripheral spongiose region. The L-PGA was administered through an implanted intrastriatal cannula coupled to an Alzet osmotic pump loaded with one of three doses of L-PGA (3, 5, or 13 times the normal amount of L-PGA/g wet wt rat forebrain (23 nmol/g). The magnitude of the lesion was dependent upon the concentration of buffered L-PGA and the duration of continuous pumping. The necrotic region contained macrophages and neutrophils, while condensed neurons and oligodendroglial cells were present in the pyknotic region. The spongiose region contained vacuolated neuropil and degenerating nerve cells and oligodendroglia. The spongiose region blends with the normal neuropil. A population of aspiny neurons were identified throughout the spongiose region. These neurons stained positive for NADPH diaphorase and demonstrated a somatostatin-like immunoreactivity similar to that of the aspiny neurons spared in Huntington's disease and in the neurotoxin-induced striatal-lesioned rat models of Huntington's disease.

Effect of piracetam, a nootropic agent, on rat brain monoamines and prostaglandins

Piracetam is the prototype of a new class of psychotropic drugs, the nootropic agents, which are claimed to selectively improve the higher telencephalic integrative activities. The effect of piracetam on rat brain monoamines and prostaglandins (PGs) was assessed so as to garner information on its mode of action. Two doses of the drug were used, a lower dose (20 mg/kg ip) and a higher dose (100 mg/kg, ip), the latter being known to exert a facilitatory effect on learning and memory. Piracetam produced a dose-related effect on rat brain serotonin (5HT) and noradrenaline (NA), with the lower dose inducing a decrease in 5HT levels and an increase in NA concentrations. The higher dose of piracetam produced the opposite effect. Dopamine (DA) levels were not significantly affected. The lower dose of the drug attenuated 5HT turnover and augmented that of NA, whereas the higher dose of piracetam produced the reverse effects, in clorgyline treated rats. The lower dose of piracetam produced a slight and statistically insignificant increase in rat brain PGE2 and PGF2 alpha. However, the higher dose of the drug produced marked increase in the levels of both the PGs. The observed biochemical effects may provide a basis for the nootropic effect of piracetam. However, they may also be due to the GA-BA-mimetic action of the drug, particularly those observed with the lower dose of piracetam.