An estimation of optimum dietary concentration of soy bean meal for carps (Catla catla, Labeo rohita and Cirhinus mrigala) / Uma estimativa da concentração dietética ideal de farinha de soja para carpas (Catla catla, Labeo rohita e Cirhinus mrigala)

Abstract Soybean meal is an inexpensive plant origin protein which has been used in practical diets as a replacement of animal protein such as fish meal or chicken meal, due to the uneconomical price of animal protein diets. Consequently, a research study was conducted on some commercial species of Indian major carps i.e. Catla (Cattla cattla), Rohu (Labeo rohita) and Mrigala (Cirhinus mrigala) (Hamilton, 1822) to estimate optimum dietary protein requirement of soy bean meal in diet in an intensive polyculture. Three different diets (SBM I, SBM II and SBM III) were formulated by 80%, 50% and 20% replacement of fish meal with soybean meal from a 45% fish meal diet (control).Highest monthly mean weight gain was obtained by SBM II (with 35% CP and about 50% substitution of fish meal), while SBM III (45% Crude Protein and about 20% substitution of fish meal) was stood second. All tested diets respond enormously by producing high yield as compare to control diet, though SBM II generated highest yield among all. On the bases of the following research, it was revealed that the SBM can surrogate even50% fish meal without any augmentation of other amino acids in the diet of Indian major carps.

Resumo O farelo de soja é uma proteína de origem vegetal de baixo custo que tem sido usada em dietas práticas como um substituto da proteína animal, como farinha de peixe ou farinha de frango, devido ao preço não econômico das dietas com proteína animal. Consequentemente, um estudo/pesquisa foi realizado com algumas espécies comerciais de carpas principais indianas, ou seja, Catla (Cattla cattla), Rohu (Labeo rohita) e Mrigala (Cirhinus mrigala) (Hamilton, 1822), para estimar a necessidade ideal de proteína dietética de farelo de soja na dieta em uma policultura intensiva. Três dietas diferentes (SBM I, SBM II e SBM III) foram formuladas por 80%, 50% e 20% de substituição de farinha de peixe por farelo de soja de uma dieta de 45% de farinha de peixe (controle). O maior ganho de peso médio mensal foi obtido por SBM II (com 35% PB e cerca de 50% de substituição de farinha de peixe), enquanto SBM III (45% de proteína bruta e cerca de 20% de substituição de farinha de peixe) ficou em segundo lugar. Todas as dietas testadas respondem enormemente produzindo alto rendimento em comparação com a dieta controle, embora SBM II tenha gerado o maior rendimento entre todas. Com base na pesquisa a seguir, foi revelado que o SBM pode substituir até 50% da farinha de peixe sem qualquer aumento de outros aminoácidos na dieta das carpas principais indianas.

An estimation of optimum dietary concentration of soy bean meal for carps (Catla catla, Labeo rohita and Cirhinus mrigala)

Abstract Soybean meal is an inexpensive plant origin protein which has been used in practical diets as a replacement of animal protein such as fish meal or chicken meal, due to the uneconomical price of animal protein diets. Consequently, a research study was conducted on some commercial species of Indian major carps i.e. Catla (Cattla cattla), Rohu (Labeo rohita) and Mrigala (Cirhinus mrigala) (Hamilton, 1822) to estimate optimum dietary protein requirement of soy bean meal in diet in an intensive polyculture. Three different diets (SBM I, SBM II and SBM III) were formulated by 80%, 50% and 20% replacement of fish meal with soybean meal from a 45% fish meal diet (control).Highest monthly mean weight gain was obtained by SBM II (with 35% CP and about 50% substitution of fish meal), while SBM III (45% Crude Protein and about 20% substitution of fish meal) was stood second. All tested diets respond enormously by producing high yield as compare to control diet, though SBM II generated highest yield among all. On the bases of the following research, it was revealed that the SBM can surrogate even50% fish meal without any augmentation of other amino acids in the diet of Indian major carps.

Resumo O farelo de soja é uma proteína de origem vegetal de baixo custo que tem sido usada em dietas práticas como um substituto da proteína animal, como farinha de peixe ou farinha de frango, devido ao preço não econômico das dietas com proteína animal. Consequentemente, um estudo/pesquisa foi realizado com algumas espécies comerciais de carpas principais indianas, ou seja, Catla (Cattla cattla), Rohu (Labeo rohita) e Mrigala (Cirhinus mrigala) (Hamilton, 1822), para estimar a necessidade ideal de proteína dietética de farelo de soja na dieta em uma policultura intensiva. Três dietas diferentes (SBM I, SBM II e SBM III) foram formuladas por 80%, 50% e 20% de substituição de farinha de peixe por farelo de soja de uma dieta de 45% de farinha de peixe (controle). O maior ganho de peso médio mensal foi obtido por SBM II (com 35% PB e cerca de 50% de substituição de farinha de peixe), enquanto SBM III (45% de proteína bruta e cerca de 20% de substituição de farinha de peixe) ficou em segundo lugar. Todas as dietas testadas respondem enormemente produzindo alto rendimento em comparação com a dieta controle, embora SBM II tenha gerado o maior rendimento entre todas. Com base na pesquisa a seguir, foi revelado que o SBM pode substituir até 50% da farinha de peixe sem qualquer aumento de outros aminoácidos na dieta das carpas principais indianas.

Variations in growth performance of Catla (Cattla cattla), Rohu (Labeo rohita) and Mrigal (Cirhinus mrigala) fed with varying levels of fishmeal based diets in intensive farming.

A one year feeding trial was conducted on carps i.e. Catla (Cattla cattla), Mrigal (Cirhinus mrigala) and Rohu (Labeo rohita) to find out appropriate level of fishmeal in diet and their effects on growth, survival and biomass in intensive polyculture. Three different inclusions of fishmeal were used in experimental diets (25%, 35% and 45%). Highest average daily growth was observed by 25% fish meal diet (2.18g, 2.19g and 2.34g for catla, rohu and mrigal respectively), whereas 35% fish meal based diet was next by showing 1.63g average daily growth for catla, 1.73g for rohu and 1.67g for mrigal. Mean values of monthly weight again and average daily growth showed significant differences among treatments. Growth was found to be higher in C. mrigala in case of 25% and 45% and L. rohita in case of 35% fish meal. Minimum FCR was obtained by 25% FM based diets as 3.53±0.41 followed by 45% (3.82±0.33) and 35% (4.05±0.45). The findings of this research trial determine the optimum dietary level of fishmeal and its effectiveness as an important ingredient in diets of Indian major carps. It is proved that a feed by the combination of animal and plant protein is much preferable by carps as compare to a feed with higher concentration of fish meal.

Length-weight relationships of farmed major carps (Cattla cattla, Labeo rohita and Cirhinus mrigala) fed with different sources of protein in an intensive polyculture.

The present findings provide information regarding the length-weight relationships (LWRs) of Indian major carps viz Cattla cattla, Labeo rohita and Cirhinus mrigala in an intensive polyculture system. Much work has been done in Pakistan with respect to fish LWRs, much of such work has been ignored. Carps were fed with twelve different formulated diets containing four different sources of protein i.e. fish meal (FM), all parts chicken meal (APCM), corn gluten (CGM) and soybean meal (SBM). Each type of protein is used at inclusion level of 25, 35 and 45% into the formulated diets to evaluate the minimum requirement of that ingredient for optimal growth of in-hand species. The values of slope "b" ranged from 2.20 to 4.90 for these species of carps which showed a strong healthy relationship among variables (level of protein and months).

Application of Levenberg-Marquardt technique for electrical conducting fluid subjected to variable viscosity.

In the present study, design of intelligent numerical computing through backpropagated neural networks (BNNs) is presented for numerical treatment of the fluid mechanics problems governing the dynamics of magnetohydrodynamic fluidic model (MHD-NFM) past a stretching surface embedded in porous medium along with imposed heat source/sink and variable viscosity. The original system model MHD-NFM in terms of PDEs is converted to nonlinear ODEs by introducing the similarity transformations. A reference dataset for BNNs approach is generated with Adams numerical solver for different scenarios of MHD-NFM by variation of parameter of viscosity, parameter of heat source and sink, parameter of permeability, magnetic field parameter, and Prandtl number. To calculate the approximate solution for MHD-NFM for different scenarios, the training, testing, and validation processes are conducted in parallel to adapt neural networks by reducing the mean square error (MSE) function through Levenberg-Marquardt backpropagation. The comparative studies and performance analyses through outcomes of MSE, error histograms, correlation and regression demonstrate the effectiveness of proposed BNNs methodology.

An estimation of optimum dietary concentration of soy bean meal for carps (Catla catla, Labeo rohita and Cirhinus mrigala).

Soybean meal is an inexpensive plant origin protein which has been used in practical diets as a replacement of animal protein such as fish meal or chicken meal, due to the uneconomical price of animal protein diets. Consequently, a research study was conducted on some commercial species of Indian major carps i.e. Catla (Cattla cattla), Rohu (Labeo rohita) and Mrigala (Cirhinus mrigala) (Hamilton, 1822) to estimate optimum dietary protein requirement of soy bean meal in diet in an intensive polyculture. Three different diets (SBM I, SBM II and SBM III) were formulated by 80%, 50% and 20% replacement of fish meal with soybean meal from a 45% fish meal diet (control).Highest monthly mean weight gain was obtained by SBM II (with 35% CP and about 50% substitution of fish meal), while SBM III (45% Crude Protein and about 20% substitution of fish meal) was stood second. All tested diets respond enormously by producing high yield as compare to control diet, though SBM II generated highest yield among all. On the bases of the following research, it was revealed that the SBM can surrogate even50% fish meal without any augmentation of other amino acids in the diet of Indian major carps.

Distributed fault detection and isolation in second order networked systems in a cyber-physical environment.

Modern industrial processes and cyber-physical systems (CPS) are prone to anomalies both due to cyber and physical perturbations. Cyber disturbances or attacks being more hazardous may give birth to a series of multiple coordinated faults. In order to detect and isolate such faults, this paper proposes a novel distributed fault detection and isolation scheme for second-order networked systems. The system is assumed to be working in a cyber-physical environment where it is likely to face multiple simultaneous faults. Each node has access to measurements of states of its neighboring nodes. A distributed fault detection and isolation filter (DFDIF) is designed such that fault detection and fault isolation can be obtained in a single step. Using the proposed filter, each node can detect and isolate multiple simultaneous faults in its neighboring nodes. The detection and isolation of faults with a single filter at each node reduces the overall computational burden of distributed fault detection and isolation (DFDI) scheme. The proposed framework is tested for power network and robotic formations. Finally, a comparison with existing techniques is provided to prove the effectiveness of the proposed method.

Effects of endocrine disruptor furan on reproductive physiology of Sprague Dawley rats: An F1 Extended One-Generation Reproductive Toxicity Study (EOGRTS).

The present study investigated the reproductive toxicity of furan in an Extended One-Generation Reproductive Toxicity Study in rats. Sprague Dawley F0 weaning rats (30 per sex per group) were exposed to furan orally at 0, 1, 2.5, 5, and 10 mg kg-1 for 10 weeks (males) and 2 weeks (females) and then mated. Results of F0 indicated that in the furan-treated groups (5 mg kg-1 and 10 mg kg-1), body weight (bw) gain decreased during prebreed and gestational period while increased during lactation periods. F0 animals prebreeding exposure resulted in head tilt and foot splay at 10 mg kg-1. Number of live pups at birth were decreased (p < 0.001) at 10 mg kg-1. At postnatal day (PND) 70, a significant (p = 0.03) decrease in testosterone levels of male rats and estrogen levels of female rats (p = 0.05) was observed in 10 mg kg-1 furan-treated group in F1 generation. Luteinizing hormone, follicle-stimulating hormone, and progesterone levels were also reduced, but their reduction was not statistically significant in all groups. In higher dose furan group (10 mg kg-1), testicular and ovarian weights were reduced in F1 generation at PND 70, with decreased daily sperm production (p = 0.01) and disturbed estrous cyclicity (p < 0.01). Some histopathological changes were also observed in testis and ovaries in groups whose parents were previously exposed to 10 mg kg-1 bw of furan group. Based on the above results, it is suggested that exposure to food-based contaminant furan induced remarkable changes in the F0 (parental stage) and F1 (offspring, pubertal, and adult stage) generations of Sprague Dawley rats.

Effect of distillery yeast sludge on growth performance, nutrient digestibility and slaughter parameters in Japanese quails.

This study was planned to evaluate the effect of distillery yeast sludge (DYS) as a protein source on growth performance, nutrient digestibility and slaughtering parameters in Japanese quail birds. For this purpose, six hundred day-old quails were randomly distributed into six dietary treatments. These dietary treatments were; G1 (Control Group) fed a basal diet (CP 24%, ME 2900 kcal/kg) without DYS, while other dietary treatments were G2, G3, G4, G5 and G6 fed basal diet containing DYS @ 1.5, 3.0, 4.5, 6.0 and 7.5%, respectively. It was observed that feed intake and weight gain tended to increase (P < 0.05) up to 3% DYS. Better (P < 0.05) feed conversion ratio (FCR) was observed in birds fed diet containing DYS at the level of 1.5 and 3%. Dry matter and crude protein digestibility decreased with increasing levels of DYS (P < 0.05). Cost of production per 100 g of weight gain was also less in birds fed diet containing 3% DYS. Study revealed that inclusion of distillery yeast sludge in the diet of Japanese quails up to 3% improves the growth performance and economics efficacy.

Crowdsourcing Evaluation of Ureteroscopic Videos Using the Post-Ureteroscopic Lesion Scale to Assess Ureteral Injury.

INTRODUCTION AND OBJECTIVES: We hypothesized that crowdsourcing assessments could be applied to the Postureteroscopic Lesion Scale (PULS) for ureteral injury. METHODS: At a single institution, we prospectively digitally recorded 14 ureters at the terminal portion of standard ureteroscopic procedures. Each recording was reviewed by 10 global experts to determine a mean PULS score. Following training, the Crowd-Sourced Assessment of Technical Skills, C-SATS® (C-SATS, Inc., Seattle, WA) platform was used to obtain crowd-based reviews. The mean crowd PULS scores was determined using the linear mixed-effects (LME) model. The intraclass correlation coefficient (ICC) was calculated to measure the agreement among experts. Spearman's rank correlation (rho) was used to quantify the strength of the relationship between the crowd LME mean and the experts. RESULTS: Ten expert's reviews and 2100 layman reviews were obtained in 21 days and 49 hours, respectively. The ICC for the 10 experts was 0.68 (95% confidence interval 0.49, 0.86). When the expert mean PULS was <1, the crowd scored those recordings at 1 or greater. The highest scored recording by the experts was a 3.2, which the crowd scored at 2.25. The correlation between the crowd LME means and expert means across all videos was 0.70 (p = 0.0056) indicative of moderately strong agreement. CONCLUSION: In this initial application of crowd-sourced evaluation of ureteral injury, there was a moderately strong correlation between crowd and expert ratings. Refinement of the training, through exposure to the nuances of ureteral injuries, in particular for PULS <1 or ≥3, may lead to better crowd/expert correlation. Compared to expert review, crowd data can be collected with much greater efficiency.

Copper deficiency, a new triad: anemia, leucopenia, and myeloneuropathy.

Clinical copper deficiency is now more frequently recognized. Hematologically, it can present as anemia (microcytic, normocytic, or macrocytic) and neutropenia. Thrombocytopenia is relatively rare. Neurologically, it can manifest as myelopathy and peripheral neuropathy simulating subacute combined degeneration. Bone marrow findings can mimic myelodysplasia resulting in occasional inappropriate referral for bone marrow transplantation. Other conditions with similar presentations include infections, drug toxicity, autoimmunity, B12 deficiency, folate deficiency, myelodysplastic syndrome, aplastic anemia, and lymphoma with bone marrow involvement. Hematological, but not neurological, manifestations respond promptly to copper replacement, making early diagnosis essential for good outcome. Common risk factors for copper deficiency are foregut surgery, dietary deficiency, enteropathies with malabsorption, and prolonged intravenous nutrition (total parenteral nutrition). We present a unique case of copper deficiency, with no apparent known risk factors.

Acute Appendicitis: An Extracolonic Manifestation of Clostridium difficile Colitis.

The current report is the case of a 30-year-old male patient who presented with symptomatology suggestive of appendicitis. However, careful history-taking and laboratory tests led to the diagnosis of Clostridium difficile colitis, resulting in successful nonsurgical management of this patient. Although both appendicitis and C. difficile colitis are common conditions, they are rarely diagnosed concurrently. This is reflected by paucity of literature describing this manifestation. Given this current presentation, the authors contend that the manifestation of extracolonic colitis within the appendix is possibly underdiagnosed or misdiagnosed as an acute appendicitis and thus potentially results in unnecessary surgical intervention. This report reminds physicians to consider the medical approach to managing acute appendicitis given the possibility of underlying C. difficile colitis as the causative factor.

How can we Improve on Modeling Nicotine Addiction to Develop Better Smoking Cessation Treatments?

Clinically effective smoking cessation treatments are few in number, mainly varenicline, bupropion, and nicotine replacement therapy being prescribed by health organizations. Of the many compounds tested for smoking cessation, a good proportion fail in human trials despite positive findings in rodents. This chapter aims to cover the uses and some pit falls of current methodologies employed to discover clinical treatments in the laboratory. Complicating factors include the complex nature of genetics in tobacco smoking and the comorbidity associated with other psychiatric disorders, which has not been addressed fully in the rodent laboratory. This chapter reviews the evidence from intravenous nicotine self-administration studies and proposes modifications on how we can improve the validity of the animal models by incorporating clinically relevant factors considered to be critical in tobacco smoking. For example, choice procedures that incorporate alternative reinforcers, use of reinstatement models, and second-order schedules of reinforcement are proposed to have better scientific validity that may lead to better clinical outcomes. Furthermore, improved experimental methods will also improve our chances of discovering effective treatments that ultimately may mitigate the effects of tobacco smoking with regard to health worldwide.

Examination of the metabolite hydroxybupropion in the reinforcing and aversive stimulus effects of nicotine in rats.

BACKGROUND: Preclinical studies with bupropion in rodent models of nicotine dependence have generated equivocal findings with regard to translating the clinical efficacy of the antidepressant as a smoking cessation agent. OBJECTIVE: Given that rats are poor metabolizers of bupropion, the present experiments examined (2S,3S)-hydroxybupropion, the major active metabolite, on the positive reinforcing and aversive stimulus properties of nicotine in rats. METHODS: In male hooded Lister rats, (2S,3S)-hydroxybupropion (1.0-10.0 mg/kg IP) was tested on intravenous nicotine (0.03 mg/kg/inf) self-administration behaviour for three sessions (n = 8), and in another experiment, the same doses of (2S,3S)-hydroxybupropion were tested in a conditioned taste aversion procedure to assess the aversive stimulus properties of nicotine, a function implicated in the regulation of nicotine intake. RESULTS: (2S,3S)-hydroxybupropion attenuated nicotine intake in a manner similar to that produced by mecamylamine pretreatment (1.0 mg/kg SC). This effect on nicotine-taking was specific since these doses had no effect on responding maintained by sucrose presented orally (200 µl of 5 % w/v). (2S,3S)-hydroxybupropion (1, 3 and 10 mg/kg IP) pretreatment failed to modify the aversive effects produced by a small dose of nicotine (0.1 mg/kg SC). CONCLUSIONS: These results demonstrate this metabolite to specifically modify the positive reinforcing effects of nicotine without affecting its aversive motivational effects. We propose that the clinical efficacy of bupropion may be due to a combination of effects produced by bupropion and/or its active metabolite (2S,3S)-hydroxybupropion involving the inhibition of reuptake of dopamine and noradrenaline in reward centres of the brain and the noncompetitive antagonism of neuronal nicotinic receptors.

Neuroanatomical targets of reboxetine and bupropion as revealed by pharmacological magnetic resonance imaging.

RATIONALE: One of the key targets of psychopharmacology research is to determine the potential sites of action of antidepressants in order to characterise their underlying mechanism of action. OBJECTIVE: Using blood oxygenation level-dependent (BOLD) pharmacological magnetic resonance imaging (phMRI), the neuroanatomical target-sites of reboxetine (a selective noradrenaline reuptake inhibitor) and bupropion (an antidepressant with stimulatory effects on dopamine and potentially on noradrenaline) were mapped. METHODS: Separate groups of rats were challenged acutely or chronically (daily injections for 14 days) with saline or psychoactive compounds and scanned. Subsequent statistical parametric mapping of the main effects of the drug was performed by identifying changes in the BOLD signal. RESULTS: Acute reboxetine challenge at a low dose (10 mg/kg i.p.) produced positive BOLD responses specifically in the hypothalamus, whereas a larger dose (30 mg/kg i.p.) produced activations in the hypothalamus, anterior hippocampus and prefrontal cortex. Chronic reboxetine (30 mg/kg i.p.) treatment induced increased BOLD responses in the posterior hippocampus and prefrontal cortex, while no significant contrast changes were observed in the hypothalamus and a significant decrease was apparent in the amygdala. In contrast, acute bupropion (15 and 30 mg/kg i.p.) challenge in both doses produced no significant contrast changes in the regions of interest. However, chronic bupropion treatment (30 mg/kg i.p.) produced robust increases in BOLD responses in the hippocampus, amygdala and prefrontal cortex. CONCLUSION: In summary, this study demonstrates that reboxetine and bupropion evoke a significant increase in BOLD functional activity in specific regions of the brain, including the hypothalamus, hippocampus, prefrontal cortex and amygdala. Furthermore, the study illustrates the potential value of pharmacological MRI in rodents to delineate pharmacologically induced changes in regional brain function.

Examining the clinical efficacy of bupropion and nortriptyline as smoking cessation agents in a rodent model of nicotine withdrawal.

RATIONALE: At present, there is a lack of an established animal model to demonstrate the clinical efficacy of smoking cessation agents in the laboratory. The aim of this study was to compare the effects of the antidepressants bupropion and nortriptyline, clinically proven smoking cessation aids, within a rodent model of a nicotine withdrawal based on somatic measures. MATERIALS AND METHODS: Male hooded Lister rats were chronically exposed to nicotine (3.16 mg kg1 day1) for 7 days via SC implanted ALZET osmotic minipumps. Animals were acutely pre-treated with bupropion (10, 30 or 60 mg/kg, IP) or nortriptyline (1.5, 4.7 and 15 mg/kg, IP), and nicotine withdrawal was precipitated by mecamylamine (1 mg/kg). RESULTS: Precipitation of nicotine withdrawal led to an increase in somatic signs including body shakes, chews, eye blinks, foot licks, head shakes and ptosis. Bupropion dose-dependently decreased the total abstinence scores and reduced the occurrence of some individual somatic signs. Pre-treatment with 60 mg/kg bupropion did not result in a significant increase in total abstinence scores or individual somatic signs scores after mecamylamine challenge, compared to the mecamylamine control group, suggesting nicotine withdrawal is fully attenuated at this dose. Similarly, the highest dose of nortriptyline reduced total abstinence scores and some individual somatic signs to the level of the mecamylamine control group. However, nortriptyline was only effective at alleviating somatic measures of withdrawal at doses which also suppressed locomotor activity. CONCLUSION: In concurrence with clinical findings proposing alleviation of withdrawal states as a possible mechanism of bupropion and nortriptyline's smoking cessation action, both drugs were found to ameliorate somatic signs of nicotine withdrawal in rodents.

Evaluation of drug release kinetics from ibuprofen matrix tablets using HPMC.

The aim of this study is to develop a once-daily sustained release matrix tablet of ibuprofen using hydroxypropyl methylcellulose (HPMC) as release controlling factor and to evaluate drug release parameters as per various release kinetic models. In order to achieve required sustained release profile tablets were directly compressed using Avicel pH 101 and Magnesium stearate. The formulated tablets were also characterized by physical and chemical parameters and results were found in acceptable limits. Different dissolution models were applied to drug release data in order to evaluate release mechanisms and kinetics. Criteria for selecting the most appropriate model was based on linearity (coefficient of correlation). The drug release data fit well to the Higuchi expression. Drug release mechanism was found as a complex mixture of diffusion, swelling and erosion.

Cocaine self-administration in rats with histories of cocaine exposure and discrimination.

RATIONALE: Interrelationships between the discriminative stimulus and reinforcing properties of psychoactive drugs and the way in which they may interact to control drug intake are unclear. Studies have shown that drug history can influence the expression of drug-produced behavioral effects. OBJECTIVE: The present study examined the acquisition and maintenance of intravenous cocaine self-administration in rats with a history of drug discrimination. METHODS: Two groups of male hooded rats (n=12 each) were successfully trained in a single-lever food-reinforced procedure to discriminate cocaine (10 mg/kg) from saline. Control groups (n=12 each) received drug injections and/or saline injections only and lever-pressed for food reinforcers with no discrimination training. Subsequently, all subjects were implanted with chronic jugular catheters and allowed to nose-poke for infusions of cocaine (0.2 mg/kg per infusion). RESULTS: Initial rates of responding were similar for all groups. Acquisition of self-administration on a FR-10 schedule of drug delivery was significantly faster for cocaine-exposed rats in comparison to all other groups (P<0.02). There were no differences between groups in the breaking points of cocaine and saline on a progressive ratio schedule of self-administration. Dose-response functions were obtained by two methods and were similar for all groups. CONCLUSION: These results are consistent with earlier studies demonstrating weakly sensitized primary reinforcing properties of cocaine in preexposed rats. Previous learning to discriminate cocaine impaired this sensitization.