Effectiveness of chain‐springs on leghold traps for reducing injuries to captured brushtail possums (Trichosurus vulpecula)

Abstract

Leghold traps continue to be an essential tool for managing brushtail possums (Trichosurus vulpecula) in New Zealand. Concerns about the injuries such traps cause have given rise to efforts to make these traps more humane. One trap modification that had potential for reducing injuries was the placement of an appropriately sized spring between two links of a trap chain to provide a cushioning effect when the chain is extended. Such springs were added to Lanes‐Ace and Victor No. 1½ traps and the injuries caused to captured possums were compared with those to possums captured in the same traps without springs or in Victor No. 1 traps. The addition of chain‐springs reduced the severity of injuries significantly, but injury scores were still significantly higher than for possums captured in Victor No. 1 traps. Consequently, although chain‐springs improved the welfare performance of the Lanes‐Ace and Victor No. 1½ traps, they did not do so to such an extent that those traps could be considered as humane as the currently acceptable Victor No. 1 traps.     

Flower choice by naïve young crab spiders and the effect of subsequent experience

Initial responses of na?ve individuals to critical environmental stimuli provide important information about the innate contribution to behaviour, and subsequent responses to the same stimuli may show the role of experience in mediating those initial responses. To test the role of these factors, I measured initial patch choices and giving-up responses of just-emerged, na?ve, second-instar crab spiders, Misumena vatia, on several hunting sites they encountered after leaving their natal nests. In follow-up tests I measured the effects of these experiences on subsequent patch choice decisions. The choice of hunting sites is a vital decision at all stages of the life cycle for sit-and-wait predators such as Misumena. In their initial tests these spiderlings remained more frequently on goldenrod (Solidago spp.) flowers than on green or yellow goldenrod buds, a preference they retained through tests run on 5 consecutive days. Individuals on green and yellow buds shifted sites more quickly and frequently than those from flowers, and made most of these moves to flowers, which attracted many more prey than did buds. These differences were not affected by age, energetic condition, or loss of information over the period of the experiment. Once spiderlings moved from buds, they showed a high, increasing tendency to move from buds in subsequent runs, those from flowers showed a consistently low tendency. These results suggest that spiderlings retain their innate behavioural patterns through the second instar, but that experience also plays a modest role in patch choice at this stage. Copyright 2000 The Association for the Study of Animal Behaviour.     

Quantitative analysis of parasite DNA in the blood of immunized and naïve mice after infection with Neospora caninum

Real-time PCR was used to study the duration and level of parasitaemia in mice immunized with immune-stimulating complexes (iscoms) containing recombinant NcSRS2, one of the immunodominant surface antigens of Neospora caninum. After challenge infection, blood was collected daily for 9 days. During this period the amounts of parasite DNA detected in immunized mice were significantly lower (P<0.001), and the duration of parasitaemia appeared to be shorter, than in non-immunized controls. Furthermore, the degree of parasitaemia seemed to correlate well with the amount of N. caninum DNA in the brain 3 weeks post-inoculation and with disease severity measured as changes in body weight. These results indicate that the protective immunity induced by the NcSRS2-iscoms was sufficient to reduce the level of parasitaemia, which probably reduced the number of parasites reaching the brain, and could be the reason for the reduction in brain parasite load and clinical symptoms. Furthermore, real-time PCR was found to be a sensitive means for rapid assessment of N. caninum in blood.     

Glycans define the stemness of naïve and primed pluripotent stem cells

Cell surface glycans are tissue-specific and developmentally regulated. They function as essential modulators in cell-cell interactions, cell-extracellular matrix interactions, and ligand-receptor interactions, binding to various ligands, including Wnt, fibroblast growth factors, and bone morphogenetic proteins. Embryonic stem (ES) cells, originally derived from the inner cell mass of blastocysts, have the essential characteristics of pluripotency and self-renewal. Recently, it has been proposed that mouse and human conventional ES cells are present in different developmental stages, namely pre-implantation blastocyst and post-implantation blastocyst stages, also called the naïve state and the primed state, respectively. They therefore require different extrinsic signals for the maintenance of self-renewal and pluripotency, and also appear to require different surface glycans. Understanding of molecular mechanisms involving glycans in self-renewal and pluripotency of ES cells is increasingly important for potential clinical applications, as well as for basic research. This review focuses on the roles of glycans in the two different states of pluripotent stem cells, namely the naïve state and the primed state, and the transition between these two states.     

Effects of social experience on subsequent sexual performance in naïve male Japanese quail (Coturnix japonica)

On their first sexual encounter, naïve male Japanese quail will attend to and approach a female; they sometimes mount but they do not always copulate. During the second encounter, most males successfully copulate. Although sexual experience facilitates subsequent sexual interactions, sensory cues provided by females, independent of any sexual encounter, may also enhance sexual performance. To investigate whether previous exposure to a conspecific affects subsequent sexual behavior, we allowed inexperienced males to observe an empty box, or a conspecific consisting of either an experienced female or male for 2.5 min/day on 7 days. Measures of appetitive sexual behavior were recorded during these tests. On day 8, subjects were allowed to copulate with a novel female for 5 min. On the following days, all subjects were repeatedly provided with visual access to a female and allowed to mate. In the pre-copulatory trials males initially exhibited a high frequency of appetitive responses that dissipated with repetition. Pre-copulatory experience also significantly affected motivation to mate with subjects exposed to females copulating more quickly than other subjects. Post-copulatory appetitive behavior also differed between groups: control subjects showed the highest behavioral frequency followed by males exposed to females and finally males exposed to males. These data indicate that pre-copulatory social experience profoundly influences subsequent sexual behavior and probably reproductive success. This experience effect is independent of any hormonal effect (such as one resulting from changes in secretion following different social interactions) given that the subjects were castrates chronically treated with testosterone.     

miRNA profiling of naïve, effector and memory CD8 T cells

microRNAs have recently emerged as master regulators of gene expression during development and cell differentiation. Although profound changes in gene expression also occur during antigen-induced T cell differentiation, the role of miRNAs in the process is not known. We compared the miRNA expression profiles between antigen-specific na?ve, effector and memory CD8+ T cells using 3 different methods--small RNA cloning, miRNA microarray analysis and real-time PCR. Although many miRNAs were expressed in all the T cell subsets, the frequency of 7 miRNAs (miR-16, miR-21, miR-142-3p, miR-142-5p, miR-150, miR-15b and let-7f) alone accounted for approximately 60% of all miRNAs, and their expression was several fold higher than the other expressed miRNAs. Global downregulation of miRNAs (including 6/7 dominantly expressed miRNAs) was observed in effector T cells compared to na?ve cells and the miRNA expression levels tended to come back up in memory T cells. However, a few miRNAs, notably miR-21 were higher in effector and memory T cells compared to na?ve T cells. These results suggest that concomitant with profound changes in gene expression, miRNA profile also changes dynamically during T cell differentiation. Sequence analysis of the cloned mature miRNAs revealed an extensive degree of end polymorphism. While 3'end polymorphisms dominated, heterogeneity at both ends, resembling drosha/dicer processing shift was also seen in miR-142, suggesting a possible novel mechanism to generate new miRNA and/or to diversify miRNA target selection. Overall, our results suggest that dynamic changes in the expression of miRNAs may be important for the regulation of gene expression during antigen-induced T cell differentiation. Our study also suggests possible novel mechanisms for miRNA biogenesis and function.     

Characterization of the psychological, physiological and EEG profile of acute betel quid intoxication in naïve subjects

Betel quid use and abuse is wide spread in Asia but the physiological basis of intoxication and addiction are unknown. In subjects na?ve to the habit of betel quid intoxication, the psychological and physiological profile of intoxication has never been reported. We compared the effect of chewing gum or chewing betel quid, and subsequent betel quid intoxication, on psychological assessment, prospective time interval estimation, numerical and character digit span, computerized 2 choice tests and mental tasks such as reading and mathematics with concurrent monitoring of ECG, EEG and face temperature in healthy, non-sleep deprived, male subjects na?ve to the habit of chewing betel quid. Betel quid intoxication, dose dependently induced tachycardia (max 30 bpm) and elevated face temperature (0.7°C) (P<0.001) above the effects observed in response to chewing gum (max 12 bpm and 0.3°C) in 12 subjects. Gross behavioral indices of working memory such as numerical or character digit span in 8 subjects, or simple visual-motor performance such as reaction speed or accuracy in a two choice scenario in 8 subjects were not affected by betel quid intoxication. Betel quid intoxication strongly influenced the psychological aspects of perception such as slowing of the prospective perception of passage of a 1 minute time interval in 8 subjects (P<0.05) and perceived increased arousal (P<0.01) and perceived decreased ability to think (P<0.05) in 31 subjects. The EEG spectral profile recorded from mental states associated with open and closed eyes, and mental tasks such as reading and eyes closed mental arithmetic were significantly modified (P<0.05) relative to chewing gum by betel quid intoxication in 10 subjects. The prevalence of betel quid consumption across a range of social and work settings warrants greater investigation of this widespread but largely under researched drug.     

The effects of pathogen challenges on the performance of naïve and immune animals: the problem of prediction

Predictive frameworks for performance under both physical and social stressors are available, but no general framework yet exists for predicting the performance of animals exposed to pathogens. The aim of this paper was to identify the key problems that would need to be solved to achieve this. Challenges of a range of hosts by a range of pathogens were reviewed to consider reductions in growth beyond those associated with reductions in voluntary food intake (VFI). Pair-feeding and marginal response studies identified the extent and mechanisms of how further reductions in growth occur beyond those caused by reduced VFI. Further reductions in growth depended on the pathogen, the host and the dose and were time dependent. In some instances the reduction in VFI fully explained the reduction in growth. Marginal response experiments showed increased maintenance requirements during exposure to pathogens, but these were different for specific amino acids. There were no clear effects on marginal efficiency. Innate immune functions, repair of damaged tissue and expression of acquired immunity caused significant but variable increases in protein (amino acid) requirements. More resistant genotypes had greater requirements for mounting immune responses. The partitioning of protein (amino acids) was found to be different during pathogen challenges. Prediction of the requirements and partitioning of amino acids between growth and immune functions appears to be a crucial problem to solve in order to predict performance during pathogen challenges of different kinds and doses. The problems of accounting for reductions in performance during pathogen challenges that are described here provide a useful starting point for future modelling and experimental solutions.     

Construction of human naïve fab library and characterization of anti-met fab fragment generated from the library

Inappropriate expression of the receptor tyrosine kinase Met and its ligand hepatocyte growth factor (HGF)/scatter factor (SF) is usually associated with an aggressive solid tumor phenotype (angiogenesis, invasiveness, and metastasis) and poor clinical prognosis. We report here the design and construction of a large, human naïve antigen-binding fragment (Fab) phage-display library with a diversity of 2.0×10⁹, which allows rapid isolation of antigen-specific human antibody fragments. A Fab fragment specifically against Met (designated hFab-Met-1) was successively selected from this library by using biopanning on Met-transfected cell line S114. The specificity of hFab-Met-1 was characterized by immunoprecipitation, Western blotting, and flow cytometry. The results demonstrate that hFab-Met-1 reacts with the extracellular domain of Met in its native conformation. Moreover, functional analysis by Madine-Darby canine kidney cell scattering and urokinase-type plasminogen activator assays demonstrated that hFab-Met-1 is not an agonist to HGF/Met signaling compared with a murine intact monoclonal antibody (MAb) Met5. To confirm that hFab-Met-1 interacts with Met-expressing tumors in vivo, I-125-labeled hFab-Met-1 was nuclear-imaged in a mouse xenograft of Met- and HGF/SF-expressing human leiomyosarcoma. Total body scintigrams were obtained between 1 and 48 h postinjection (PI). Tumor-associated activity was imaged as early as 1 h PI, and remained visible in some animals as late as 24 h PI. As expected, activity was highest in the kidneys in early images, whereas thyroid activity became predominant in later images. In conclusion, hFab-Met-1 interacts with Met both in vitro and in vivo, and is a promising candidate for clinical diagnosis and therapeutics.     

Cooperation of dendritic cells with naïve lymphocyte populations to induce the generation of antigen-specific antibodies in vitro

The production of monoclonal antibodies by hybridoma technology is dependent on lymphocytes taken from vertebrates which have to be immunized against the corresponding antigen. We present here our first experiments which should allow the replacement of this in vivo immunization step by an in vitro immunization procedure. This work provides new possibilities for the specific activation of immune cells in order to use them for the generation of antibodies which are not of murine origin. Bone marrow-derived dendritic cells were loaded with antigen and co-cultured with naïve T and B lymphocytes of non-immunized mice. The interaction and activation of the different cell types were investigated by measuring the expression of specific cell surface markers, the release of activation-dependent interleukins and the secretion of antigen-specific antibodies. We could demonstrate that dendritic cells process and present antigen fragments and activate T cells, that T cells proliferate and release activation-induced interleukins, and that B cells maturate under the influence of activated T cells and secrete antigen-specific antibodies.     

Naïve Encounters with Chimpanzees in the Goualougo Triangle, Republic of Congo

We describe the behavior of an unhabituated population of chimpanzees in the Goualougo Triangle, Republic of Congo. We encountered chimpanzee parties on 218 occasions during two field seasons (February 1999–December 1999, June 2000–June 2001). Overall contact rate was 0.63 contacts per day in the field (n = 347). During the first 5 min of observation, we recorded individual responses as curious, ignore, hide, or depart. In contrast to other unhabituated chimpanzees, curiosity was the most common response (84%) of individuals in the Goualougo Triangle. However, the responses were deeply integrated in the group's reaction to our arrival and behavior throughout an encounter. Based on the behavior of the majority of individuals in a group, we categorized entire contact events as naïve, ignore, nervous, or depart. Naïve contacts accounted for 69% of all encounters. Other contacts types occurred much less frequently: nervous (12%), depart (11%), ignore (8%). Naïve contacts were characterized by chimpanzees that continued to exhibit curiosity throughout the encounter, the arrival of other individuals at the contact location, and relatively prolonged contact with observers (average duration: 136 min). It is likely that the high frequency of curious responses and naïve contacts are due to the remote location of the Goualougo Triangle and the chimpanzees's lack of experience with humans. Documentation of this naïve phenomenon has been successfully used to lobby for the protection of the chimpanzees and their habitat.     

Porcine induced pluripotent stem cells analogous to naïve and primed embryonic stem cells of the mouse

Authentic or na?ve embryonic stem cells (ESC) have probably never been derived from the inner cell mass (ICM) of pig blastocysts, despite over 25 years of effort. Recently, several groups, including ours, have reported induced pluripotent stem cells (iPSC) from swine by reprogramming somatic cells with a combination of four factors, OCT4 (POU5F1)/SOX2/KLF4/c-MYC delivered by retroviral transduction. The porcine (p) iPSC resembled human (h) ESC and the mouse "Epiblast stem cells" (EpiSC) in their colony morphology and expression of pluripotent genes, and are likely dependent on FGF2/ACTIVIN/NODAL signaling, therefore representing a primed ESC state. These cells are likely to advance swine as a model in biomedical research, since grafts could potentially be matched to the animal that donated the cells for re-programming. The objective of the present work has been to develop na?ve piPSC. Employing a combination of seven reprogramming factors assembled on episomal vectors, we successfully reprogrammed porcine embryonic fibroblasts on a modified LIF-medium supplemented with two kinase inhibitors; CHIR99021, which inhibits GSK-3beta, and PD0325901, a MEK inhibitor. The derived piPSC bear a striking resemblance to na?ve mESC in colony morphology, are dependent on LIF to maintain an undifferentiated phenotype, and express markers consistent with pluripotency. They exhibit high telomerase activity, a short cell cycle interval, and a normal karyotype, and are able to generate teratomas. Currently, the competence of these lines for contributing to germ-line chimeras is being tested.     

Increase in the occurrence of abortions associated with exposure to the Bluetongue virus serotype 8 in naïve dairy herds

The transplacental transmission capacity demonstrated for Bluetongue virus serotype 8 (BTV-8) in cattle probably is associated with an increased occurrence of abortions. The objectives of this study were to quantify the effect of BTV-8 exposure on the occurrence of abortions in previously naive dairy cow herds under natural infection conditions, and to determine a possible risk period during pregnancy associated with this increase. Two criteria were considered in order to estimate the occurrence of abortion: late return-to-service after a first artificial insemination (AI), and short gestations. A late return-to-service was defined as a return taking place 90 to 200 days after a first AI. These criteria were compared between cows in herds exposed during the 2007 epizootic in France and cows in herds that were not exposed. To determine the risk period during a pregnancy, variations in the occurrence of abortions were quantified according to the stage of the pregnancy during which the exposure took place. Survival analyses were used to estimate the risk of increased occurrence of abortion associated with BTV-8 exposure, adjusted by the principal factors known to influence the risk of abortion. Exposure to the BTV-8 virus under natural conditions in previously naive dairy herds notified after clinical suspicion during the 2007 epizootic was associated with an increase in the occurrence of abortions, regardless of the stage of pregnancy. The at-risk gestation period depended on the criteria used to detect abortions. The mean effect of BTV-8 exposure in the ensemble of detected outbreaks corresponded to an increase of 6.7% in late return-to-service. BTV-8 exposure during the first 3 mo of gestation was associated with a 15% increase in late return-to-service for cows with no return-to-service at 90 days, while this increase was 6% for exposure starting from the third month of gestation (in outbreaks detected in September). BTV-8 exposure from the third month of gestation was associated with a 1.9% increase of short gestations. The effect of exposure was more pronounced for outbreaks detected early in the epizootic compared with those detected later.     

Fibroblasts enhance the in vitro survival of human memory and naïve B cells by maintaining intracellular levels of glutathione

To gain insight into the mechanism of memory B cell survival, we cultured highly purified subpopulations of tonsillar B cells with tonsillar fibroblasts. The fibroblasts greatly enhanced the survival of memory and na?ve B cells but did not delay the rapid apoptosis of germinal center B cells. B cell activation was not observed during the period of culture, as shown by the absence of activation markers and of cycling cells. These findings were reproduced when the B cells were physically separated from the fibroblasts by a semi-permeable transwell-membrane, indicating that the survival factor(s) were diffusible. Several cytokines including IL-6, IL-15, and VEGF were tested for survival activity but none could replace the fibroblasts. However, the addition of reduced glutathione (GSH) to the na?ve and memory B cells significantly enhanced their survival, and depletion of GSH resulted in rapid loss of B cell viability. Furthermore, intracellular glutathione levels were maintained when the B cells were co-cultured with fibroblasts. Our results suggest that glutathione plays an important role in the survival of memory and na?ve B cells in the presence of stromal cells.     

The activation, by antigen, of naïve TCR transgenic CD4 T cells cultured at physiological, rather than artificially high, frequencies more accurately reflects the in vivo activation of normal numbers of naïve CD4(+) T cells

The majority of in vitro studies investigating the activation of na?ve TCR transgenic T cells routinely employ an artificially high frequency of such cells. To assess whether employing high frequencies of TCR transgenic cells in vitro accurately reflects the in vivo activation of a normal number of T cells, we cultured between 300 and 3×10(6) Rag2(-/-) DO11.10 T cells per well under otherwise identical conditions. We find that those T cells cultured at low frequencies proliferate more and are more potently activated, as assessed by the expression of CD44 and CD62L, each giving rise to a much larger number of cytokine producing cells, comparable to the number generated in vivo when a normal number of CD4(+) T cells are activated. The effect of T cell frequency on the level of their activation was not due to differences in MHCII or CD80/86 expression by B cells, the major APC population present, nor to increased death of B cells in high frequency cultures. Taken together, our observations illustrate the necessity of culturing na?ve TCR transgenic CD4(+) T cells at a physiological frequency if one is to more accurately recapitulate the in vivo activation of na?ve CD4(+) T cells.     

Effect of the insect parasite Hyposoter exiguae (Viereck) on the carbohydrate metabolism of its host,Trichoplusia ni (Hübner)

Parasitization of Trichoplusia ni by Hyposoter exiguae resulted in elevations in the haemolymph trehalose concentration and fat body glycogen level. These increases in tissue carbohydrate reserves were accompanied by an elevation in the maximal velocities of fat body phosphofructokinase and fructose 1,6 bisphosphatase. The activity of the latter, however, was several-fold greater than that of phosphofructokinase and the potential gluconeogenic flux through the fructose phosphate step was, therefore, markedly increased following parasitization. The changes in adenylate levels in parasitized fat body, specifically an increase in AMP and decrease in ATP, were consistent with an elevation in phosphofructokinase activity in vivo but not in fructose 1,6 bisphosphatase activity. The latter enzyme, however, was shown to be less sensitive to both AMP and fructose 2,6 bisphosphate inhibition in fat body of parasitized individuals. Decreased haemolymph glucogenic amino acid concentrations and an increase in faecal uric acid level accompanied the above effects. It was concluded that parasitization of T. ni by H. exiguae caused a stress-induced hyperglycemia that may result from an alteration in the hormonal regulation over carbohydrate synthesis.     

Antigen-specific accumulation of naïve, memory and effector CD4 T cells during anterior uveitis monitored by intravital microscopy

Uveitis is an immune-mediated ocular disease and a leading cause of blindness. We characterized a novel model of uveitis with intravital microscopy. Transfer of ovalbumin-specific T cells from DO11.10 spleen to BALB/c recipients and subsequent challenge with ovalbumin in the anterior chamber of the eye resulted in anterior uveitis. Antigen-specificity was verified by injection of irrelevant antigen and transfer of T cells with a different specificity. Subsets of CD4 T cells, including naive (DO11.10 RAG(-/-)) and in vitro-activated Th2 effector CD4 T cells, infiltrated anterior segment tissues early in the inflammation. Memory-like CD44(high) CD4 T cells from unprimed transgenic mice and in vitro-activated Th1 effector CD4 T cells accumulated to larger numbers than naive or Th2 effector cells at 48 and 72 h. Of these, the alpha(2)-integrin+CD4 unprimed T cells entered the eye more efficiently, and antibody to alpha(2)-integrin markedly inhibited the inflammatory response. Intravital microscopy revealed the early arrival and antigen-specific accumulation of CD4 T cells in inflamed tissue and should be helpful in understanding T cell migration to other organs.     

Effects of citalopram on cognitive performance in passive avoidance, elevated plus-maze and three-panel runway tasks in naïve rats

Recent studies have shown that learning and memory capacity is disturbed in depressive patients, and it is important to reveal the effects of antidepressant drugs on cognitive function in depressive patients with memory problems. Citalopram, a selective serotonin reuptake inhibitor (SSRI), is one of the most widely used drugs for the treatment of disorders related to serotonergic dysfunction like depression and anxiety. Contradictory findings exist regarding the effects of SSRIs on memory. The aim of this study is to investigate whether citalopram affects memory in various models of learning and memory tasks in rats. Citalopram (at 20 and 50 mg/kg) significantly shortened the retention latency in the passive avoidance test and prolonged the transfer latency on the second day at 10 and 50 mg/kg doses in the elevated plus-maze test. Citalopram also significantly increased the number of errors (at the 10 mg/kg dose) and prolonged the latency values compared to the control group in both reference and working memory trials in the three-panel runway test. Citalopram also impaired reference memory trials of animals at the 20 mg/kg dose. In conclusion, citalopram impaired cognitive performance in passive avoidance, elevated plus-maze and three-panel runway tasks in naive rats. These effects might be related to serotonergic and nitrergic mechanisms, which need to be investigated in further studies.     

Inducible nitric oxide synthase inhibitor aminoguanidine, differently affects Morris water maze tasks of ovariectomized and naïve female rats

The role of ovarian hormones, nitric oxide, and their interaction on learning and memory has been widely investigated. The objective of present study was to investigate different effects of chronic administration of inducible nitric oxide synthase inhibitor, aminoguanidine (AM) on learning and memory of ovariectomized (OVX) and na?ve (Sham) female rats. Thirty-two rats were divided into four groups: 1) Sham, 2) OVX, 3) Sham-AM and 4) OVX-AM. The animals of Sham-AM and OVX-AM chronically received 100 mg/kg/day of aminoguanidine during 8 weeks before 5 test days. The animals in Sham and OVX groups received 1 ml/kg saline instead of aminoguanidine. The animals were tested in Morris water maze and the escape latency and traveled path to reach the platform were compared between groups. On the fifth day, the platform was removed, and the animals were allowed to swim for 60 s ( prob trial). The time spent in the target quadrant (Q1) was compared between groups.Results showed that the escape latency and traveled path in OVX group were significantly higher than in the Sham group (p<0.01). Both escape latency and traveled path in the Sham-AM group was significantly higher than in the Sham group (p<0.01) however, there was no significant difference between OVX-AM and OVX groups.The time spent by the animals of OVX group in the target quadrant (Q1) during the probe trial was significantly lower than that in the Sham group (p<0.01). The animals of the Sham-AM group spent shorter times in the target quadrant in comparison with the Sham group (p<0.01). There was no significant difference between the OVX and OVX-AM groups in the time spent in tarthe get quadrant. It is concluded that the effect of aminoguanidine on learning and memory is different in the presence or absence of ovarian hormones but it needs further investigation.