Biomedical subjects

Keiko Shimizu

Publications and source records attributed to Keiko Shimizu.

At least 37 records · Page 2Linked to original sources

PubMed2004

Differential expression patterns of TrkB ligands in the macaque monkey brain.

We measured the concentrations of brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT-4) in the brains of mature and developing macaque monkeys. In the adult macaque brain, the highest level of BDNF was found in the hippocampus. Comparisons between cortical regions showed higher levels of BDNF in the prefrontal, temporal, and parietal association cortices than elsewhere. In contrast, NT-4 levels were 3-30 times lower than those of BDNF. During development, the contents of BDNF and NT-4 protein in cerebral cortices were highest at the postnatal second month and at embryonic day 140, respectively. These results suggest that the two TrkB ligands, BDNF and NT-4, may be differently regulated and might play separate roles in monkey cortical development.

Animals↗

PubMed2004

Hormone profiles and reproductive characteristics in wild female Japanese macaques (Macaca fuscata).

In this study we investigated the reproductive characteristics of wild female Japanese macaques (Macaca fuscata fuscata) in 2 nonconsecutive years using noninvasive methods to monitor physiological events. We detected ovulation dates and ascertained conceptions from fecal hormone profiles. First ovulations occurred from middle October to early November in 1997, and from middle to late November in 1999. Most females conceived during their first ovarian cycle. On average, postconception bleeding occurred 18.4 days after ovulation, and menstruation occurred 13.7 days after ovulation. The average gestation length was 176.3 days. The average degree of facial redness and the percentage of females that copulated synchronously changed across the ovarian cycle and peaked in the periovulatory period. Although prolonged periods of postconception copulation have been reported in previous studies, they did not occur in this study, which suggests that such behavior may not be a species-typical characteristic. Female fertility varied between the 2 years. The copulation rates of females with no infant <1 year of age were 100% (14/14) in 1997 and 45.5% (5/11) in 1999. The ovulation rates of the female subjects that we chose for hormonal assays were 100% (9/9) in 1997 and 50.0% (3/6) in 1999. Th conception rates of these selected females were 100% (9/9) in 1997 and 16.7% (1/6) in 1999. The birth rates (the number of females that delivered divided by the total number of adult females in the troop) were 73.3% (11/15) in 1998 and 6.7% (1/15) in 2000. The modified birth rates (the number of females that delivered /the number of adult females with no infant <1 year of age) x 100 were 78.6% (11/14) in 1998 and 9.1% (1/11) in 2000.

Animals↗

PubMed2003

Peripartum sex steroid changes and maternal style in rhesus and Japanese macaques.

The subtle and complex relationships between the sequential maturation of the endocrine systems during pregnancy and parturition, and the hormonal role in activating the central nervous system to express maternal behavior in primates, are far from being completely understood. Recent studies on the association between sex steroids and maternal behavior have yielded conflicting results in this group. Here we use a comparative approach to assess the correlation between changes in the peripartum endocrine profiles and maternal styles in two closely related macaque species, housed in analogous environments. We included in this study the first seven Japanese macaque and seven rhesus macaque mother-infant pairs born during the birth season of 2001 at the Primate Research Institute, Kyoto University, Japan. We observed each pair 3h/week (six weekly 30-min observation sessions) during the first 12 weeks of lactation. We collected fecal samples twice a week from each mother, starting 4 weeks before parturition and ending 4 weeks after parturition. We tested the hypothesis that neuroendocrine changes during pregnancy and lactation might specifically contribute to the regulation and timing of infant rejection. Despite their biological similarities, we observed a clear difference in maternal style between the two groups concerning rejection rates: rhesus macaque mothers rejected their infants earlier and more frequently throughout the whole 12 weeks of study. On the other hand, protectiveness showed similar patterns and values in the two groups, and maternal warmth was significantly higher in the rhesus group, but it followed a similar pattern over time. We also confirmed an association between maternal rejection and excreted estrogen, but not excreted progesterone, for Japanese macaques. This association was not apparent for the rhesus macaques. This result, coupled with the observation that rhesus mothers are more rejecting than Japanese macaque mothers, tends to support our hypothesis. As a group, rhesus macaques are less inhibited in the rejection of their infants, and this is paralleled by a less marked change in the primacy of estrogen in the last phase of pregnancy. On the contrary, the Japanese group is characterized by higher levels of E(1)C and the E(1)C/PdG ratio. Therefore, according to our hypothesis, their tendency to increase the rejection rate may be suppressed through a feedback loop that enhances maternal motivation and results in a more tolerant outcome toward the infant.

Animals↗

PubMed2003

Inhibin B is the major form of inhibin secreted from testes in male Japanese macaques ( Macaca fuscata).

In order to clarify the cellular source and forms of bioactive inhibin in male Japanese macaques ( Macaca fuscata), circulating concentrations of inhibin A and B, and immunohistochemical localization of inhibin subunits in testis were studied. Plasma concentrations of testosterone were also measured. The present study showed that inhibin B was clearly detected in the plasma of male Japanese macaques. Moreover, concentrations of both inhibin B and testosterone during the breeding (mating) season were significantly higher than those of the non-breeding season. On the other hand, plasma inhibin A was detected neither during the breeding seasons nor during the non-breeding seasons. Positive stainings with alpha and betaB subunit antibodies were observed in the Sertoli cells, however staining with betaA subunit antibody was not observed in the testicular samples. These results indicate that inhibin B is the major circulating inhibin and probably secreting from Sertoli cells in male Japanese macaques.

Animals↗

PubMed2003

Levels of serum brain-derived neurotrophic factor in primates.

Brain-derived neurotrophic factor (BDNF) has been reported to exist not only in nervous tissue but also in serum. In contrast to the wealth of knowledge regarding the various physiological functions of BDNF in the nervous system, information about possible roles in other systems is limited. To elucidate the physiological function of serum BDNF in primates, it is first necessary to establish a method to determine the levels of BDNF in serum of primates. In the present study, we established an enzyme-linked immunosorbent assay (ELISA) method which we used to measure levels of serum BDNF in non-human primates. We found that serum BDNF levels were similar among several species of primates. The present results suggest that our BDNF ELISA may be useful in measuring serum BDNF concentration as a physiological marker, and that levels of serum BDNF may be similar among primates including humans.

Animals↗

PubMed2003

Mother-infant relationships and maternal estrogen metabolites changes in macaques (Macaca fuscata, M. mulatta).

This research assessed mother-infant relationships in rhesus and Japanese macaques living in analogous captive social groups, and monitored changes in the levels of excreted estrogen metabolites during the peripartum period. Each mother-infant pair was focally observed 3 h per week during the first 12 weeks of life of newborns. Fecal samples were collected twice a week from each mother, starting 4 weeks before delivery and ending 4 weeks after delivery. Infant-directed behaviors appeared to be consistently less protective/controlling and more rejecting in rhesus macaques than in Japanese macaques. Estrogen metabolite levels during the perinatal period were, on average, 3-fold higher in Japanese macaques and showed a sharp increase during the last weeks of pregnancy only in the Japanese macaque group. Considering the ecological and behavioral similarities between Japanese and rhesus macaques, the divergence between the two species in the onset and maintenance of maternal behavior was unexpected. This was possibly linked to the difference in the overall body size and life history, and to the striking divergence in estrogen metabolite variation during the peripartum period. Group size, social relationships, and average age of individuals in the two captive groups were not clearly involved in the recorded differences in maternal behavior.

Animals↗

PubMed2003

Comparative study of urinary reproductive hormones in great apes.

Urinary estrone conjugates (E(1)C), pregnanediol-3-glucuronide (PdG), and follicle-stimulating hormone (FSH) were determined by enzyme immunoassays (EIAs) during the normal menstrual cycle in the orangutan, gorilla, chimpanzee, and bonobo. Furthermore, the data were compared to those levels in the human and long-tailed macaque. The results showed a typical preovulatory E(1)C surge and postovulatory increase in PdG in all species. The pattern of E(1)C during the menstrual cycle in the great apes more closely resembled the human than do the long-tailed macaque. A major difference of E(1)C pattern between these species appeared in the luteal phase. In the great apes and the human, E(1)C exhibited two peaks, the first peak detected at approximately mid cycle and the second peak detected during the luteal phase. On the other hand, in the long-tailed macaque, increase of E(1)C in the luteal phase was small or nonexistent. The gorilla, chimpanzee, and bonobo exhibited similar PdG trends. The orangutan excreted one tenth less PdG than these species during the luteal phase. The long-tailed macaque also excreted low levels of PdG. The patterns of FSH in orangutan, chimpanzee, bonobo and long-tailed macaque showed a marked mid-cycle rise and an early follicular phase rise, similar to those in the human. Comparing similar taxa, a large difference was found in FSH of gorilla; there were three peaks during the menstrual cycle. Thus, there is considerable species variation in the excretion of these hormones during the menstrual cycle and comparative studies could be approached with a single method. The methods and baseline data presented here provide the basis for a practical approach to evaluation and monitoring of ovarian events in the female great apes.

Animals↗

PubMed2003

Peripartum cortisol levels and mother-infant interactions in Japanese macaques.

As evidence accumulates regarding the influence of hormones and stress-related conditions on maternal behavior, it becomes critical to better understand the relationship between physiological stress and the ability to cope with infants. Eight Japanese macaque females were observed 3 hr per week during the first 12 weeks after parturition; fecal samples were collected twice a week from each mother, starting 4 weeks before parturition and ending 4 weeks after parturition. Time spent in contact, maternal responsiveness, latency of response, and maternal rejection were measured and correlated with peripartum excreted cortisol and estradiol metabolite levels. Two indices of peripartum hormonal status were also tested against behavior: the postpartum stress index, and the postpartum cortisol/prepartum estradiol ratio (F/E). Postpartum cortisol levels showed a positive correlation with maternal rejection. The cortisol/estradiol ratio was positively correlated with rejection and latency of response, and negatively correlated with maternal responsiveness. Prepartum cortisol levels and the postpartum stress index did not correlate with any aspect of maternal behavior. Our findings suggest that hypothalamic-pituitary-adrenal (HPA) axis activity per se is not enough to predict the quality of interaction between mother and infant. Only when cortisol is high relative to estradiol could it be symptomatic of a possible negative feedback response involving stress, adrenal activity, and the ability of mothers to cope with the additional problems imposed by newborns.

Animals↗

PubMed2003

Differences in the endocrine and behavioral profiles during the peripartum period in macaques.

The present investigation aims to assess the changes in both social interaction and sex steroids excreted in feces of group-living Japanese macaques and rhesus monkeys. By comparing profiles of estrone conjugates (E1C) and pregnanediol-glucuronide (PdG) with the behavioral propensities of two closely related species living in similar environments, we could test the hypothesis that the social behavior of pregnant females shows significant hormonally mediated changes during the late prepartum and early postpartum period. We found a general tendency to withdraw from social life across pregnancy in both species. These behavioral changes were paralleled by endocrine profiles showing a slight prepartum increase in E1C during the last week in the rhesus group, whereas the increase was more marked and continuous in the Japanese macaque group. PdG increased slightly in rhesus macaques, whereas in Japanese macaques the fluctuations were not significant. Postpartum, both hormones dropped to low levels in both species, with no significant variation therein. Consequent to these changes, the E1C/PdG ratio increased significantly in late pregnancy only in the Japanese macaque group. Overall, these results show significant differences in the social behavior and endocrine profiles of two closely related species, thus complementing previous findings and indicating species-specific characteristics of the association between changes in affiliative behaviors and hormonal fluctuations. In particular, the shift between grooming performed and self-grooming, which showed the closest association with variations in the E1C/PdG ratio, could represent a reliable indicator of the change in the internal status of pregnant females, and is probably functional to infant survival.

Animals↗

PubMed2003

Paraquat leads to dopaminergic neural vulnerability in organotypic midbrain culture.

Paraquat (1,1'-dimethyl-4,4'-bipyridinium, PQ) is a herbicide to possibly induce Parkinson's disease (PD), since a strong correlation has been found between the incidence of the disease and the amount of PQ used. In this study, we examined PQ toxicity in rat organotypic midbrain slice cultures. PQ dose dependently reduced the number of dopaminergic neurons in cultured slices. Since this damage was prevented by GBR-12909, the dopamine transporter could be an initial step of the PQ induced dopaminergic neurotoxicity. The sequential treatments with lower PQ and 1-methyl-4-phenyl pyridinium (MPP+) doses, where each dose alone was not lethal, markedly killed dopamine neurons, suggesting that the exposure of a lower dose of PQ could lead to the vulnerability of dopaminergic neurons. This cell death was prevented by the inhibitors of NMDA, nitric oxide synthase (NOS), cycloheximide and caspase cascade. Neurons expressing NOS were identified inside and around the regions where dopamine neurons were packed. The cell death induced by the sequential treatments with PQ and MPP+ was also rescued by L-deprenyl and dopamine D2/3 agonists. These results strongly support that the constant exposure to low levels of PQ would lead to the vulnerability of dopaminergic neurons in the nigrostriatal system by the excitotoxic pathway, and might potentiate neurodegeneration caused by the exposure of other substances and aging.

1-Methyl-4-phenylpyridinium↗

PubMed2003

Genotyping of cytochrome p450 isoform genes is useful for forensic identification of cadaver.

Tailor-made medical treatment based on the polymorphism of genes encoding drug-metabolizing enzymes has been advocated and is being tried on an experimental basis at numerous centers. If DNA polymorphism analysis becomes routine in tailor-made medical treatment, it will be very useful in forensic identification. In this study, we determined the genotype frequencies of five p450 (CYP) isoform genes, CYP1A2, CYP2D6, CYP2E1, CYP2C9 and CYP2C19 in 196 Japanese individuals to evaluate their forensic usefulness. These genes encode the most important enzymes among the CYP superfamily that metabolize clinically used drug. The frequency of each allele agreed well with those reported previously and their genotype frequencies did not deviate from those expected from Hardy-Weinberg equilibrium. CYP2C subfamilies such as CYP2C9 and CYP2C19 on chromosome 10 showed high sequence homology, as high as over 95% in the regions flanking polymorphic sites. Although 3240 genotype combinations of these five CYP isoform genes are theoretically possible, 101 combinations were detected in this study. The genotype frequencies of these five isoform genes excluded their linkage. The following two genotype combinations showed the highest frequency of 0.036: CYP1A2*1A/*1A, CYP2D6*1/*10, CYP2E1*1/*1, CYP2C9*1/*1 and CYP2C19*1/*1 and CYP1A2*1A/*1C, CYP2D6*1/*10, CYP2E1*1/*1, CYP2C9*1/*1 and CYP2C19*1/*1. Thus, genotyping of CYP isoform genes should be useful in forensic identification.

Alleles↗

PubMed2003

Pralidoxime iodide (2-pAM) penetrates across the blood-brain barrier.

The in vivo rat brain microdialysis technique with HPLC/UV was used to determine the blood-brain barrier (BBB) penetration of pralidoxime iodide (2-PAM), which is a component of the current nerve agent antidote therapy. After intravenous dosage of 2-PAM (10, 50, 100 mg/kg), 2-PAM appeared dose-dependently in the dialysate; the striatal extracellular/blood concentration ratio at 1 h after 50 mg/kg dosage was 0.093 +/- 0.053 (mean +/- SEM). This finding offered conclusive evidence of the BBB penetration of 2-PAM. We also examined whether the BBB penetration of 2-PAM was mediated by a certain specific transporter, such as a neutral or basic amino acid transport system. Although it was unclear, the neural uptake of 2-PAM was Na+ dependent. The mean BBB penetration by 2-PAM was approximately 10%, indicating the intravenous administration of 2-PAM might be to a degree effective to reactivation of the blocked cholinesterase in the brain.

Amino Acid Transport Systems↗

PubMed2003

Urinary steroids, FSH and CG measurements for monitoring the ovarian cycle and pregnancy in the chimpanzee.

Non-invasive methods for monitoring reproductive status of chimpanzee based on the measurement of urinary steroids and gonadotropins were examined. A typical pre-ovulatory urinary estrone conjugate (E1C) surge and post-ovulatory increase in pregnandiol glucuronide (PdG) were seen during the menstrual cycle. Urinary follicle stimulating hormone (FSH) showed two peaks over the infertile menstrual cycle. The earliest changes indicating pregnancy were a coincident rise in E1C and chorionic gonadotropin (CG) levels and a concomitant fall in FSH levels. Urinary PdG levels showed a prolonged rise. Urinary E1C in the pregnant chimpanzee was higher than during the menstrual cycle and increased with advancing gestation, with maximum levels occurring near term. In the case of stillbirth, E1C and CG levels from mid- through late-pregnancy were low and the prepartum progressive increase in E1C was not shown. The data presented here are of great practical value in captive breeding management of chimpanzees.

Animals↗

PubMed2003

Protective effects of quinaprilat and trandolaprilat, active metabolites of quinapril and trandolapril, on hemolysis induced by lysophosphatidylcholine in human erythrocytes.

We examined the effects of the angiotensin converting enzyme (ACE) inhibitors captopril, enalaprilat, quinapril, and trandolapril, and their active metabolites quinaprilat and trandolaprilat, on hemolysis induced by lysophosphatidylcholine (LPC) in human erythrocytes. LPC induced hemolysis at the concentrations above the critical micelle concentration (4 microM). Propranolol, used as a reference drug, attenuated the 50% hemolysis induced by 6 microM LPC at concentrations ranging from 100 nM to 100 microM. Similarly, quinaprilat (10 microM) and trandolaprilat (10, 100 microM) significantly attenuated the LPC-induced hemolysis, but other ACE inhibitors did not. Since propranolol possesses a membrane stabilizing action correlated with high lipophilicity, it appears that the high lipophilicity of quinaprilat or trandolaprilat is responsible for the protection from the damage induced by LPC. However, quinapril and trandolapril were not effective, although both drugs have higher lipophilicity than quinaprilat and trandolaprilat. Hence, it is suggested that the high lipophilicity alone may not contribute to the protective effects of ACE inhibitors against LPC-induced hemolysis. None of ACE inhibitors attenuated the hypotonic hemolysis (60 mM NaCl), although propranolol did. Furthermore, neither propranolol (100 microM) nor quinaprilat (50 microM) and trandolaprilat (50 microM) affected LPC micelle formation, suggesting that these drugs do not directly bind to LPC. We therefore believe that the protective effects of quinaprilat and trandolaprilat on the LPC-induced hemolysis may be related physicochemically to their highly lipophilic and ACE inhibitory structures, which probably maintain erythrocyte membrane integrity by a mechanism other than ACE inhibition, prevention of LPC micelle formation or protection against osmotic imbalance.

Adrenergic beta-Antagonists↗

PubMed2003

Endocrinologic comparison of activin a secretion during pregnancy and early lactation in Japanese monkeys, chimpanzees, and humans.

Secretion of activin A in Japanese monkeys and chimpanzees during pregnancy and early postpartum periods was investigated, and the results were compared with those in humans. Plasma activin A increased throughout pregnancy in Japanese monkeys, and the level was significantly higher in the third and fourth quarters than in the first quarter. After parturition in the Japanese monkey, circulating activin A decreased to levels seen during the normal menstrual cycle. In chimpanzees, plasma activin A remained low until the third quarter of pregnancy and abruptly increased in the fourth quarter. After parturition in chimpanzees, however, circulating activin A concentrations still remained as high as levels in the fourth quarter until 42 h after parturition, then decreased to nadir levels at 1 mo after parturition, suggesting that activin A in chimpanzees may be secreted from other organs such as uterus in addition to placenta. Positive staining with inhibin/ activin alpha-, betaA-, and betaB-subunit antisera was observed in the cytoplasm of the syncytiotrophoblast of term placenta in the Japanese monkey, chimpanzee, and human. These results demonstrated that circulating activin A gradually increased from early pregnancy in Japanese monkey, whereas an abrupt increase occurred at late pregnancy in chimpanzees. These results also demonstrated that the syncytiotrophoblast of placenta is the source of activin A in Japanese monkeys and chimpanzees as well as humans.

Activins↗

PubMed2002

Changes in NT-3 and TrkC in the primary visual cortex of developing macaques.

In the present study, we measured the levels of neurotrophin-3 (NT-3) protein and mRNA by ELISA and quantitative RT-PCR, and examined TrkC-immunoreactive structures using immunohistochemical method. In the nervous system of the adult monkey, higher levels of NT-3 were found in the hippocampus and cerebellum. During the development of the primary visual cortex, detected amounts of NT-3 protein peaked at embryonic day 140 and then gradually decreased. TrkC imunoreactivity was observed in the neurons in layer VI of the primary visual cortex of an embryonic monkey. These results support the hypothesis that NT-3 is involved in the specification of axon targeting from layer VI to layer IV during the late embryonic stages.

Aging↗

PubMed2002

Efficacy of a B virus gD DNA vaccine for induction of humoral and cellular immune responses in Japanese macaques.

It is desirable to prevent dissemination of B virus (BV) in macaque colonies because transmission of BV to humans causes deadly encephalomyelitis. Vaccination of monkeys is one method that could confine spread of BV within macaque colonies. Availability of a BV DNA vaccine for use in macaques would eliminate the risk of working with infectious BV. Toward this end, we constructed a plasmid expressing the BV glycoprotein D (gD). Immunogenicity of this construct as a DNA vaccine was assessed in adult Japanese macaques by four intracutaneous injections at a dose of 500 microg per head. Results of enzyme-linked immunosorbent assay (ELISA) using a recombinant herpes simplex virus type 1 (HSV1) gD, a homologue of BV gD, showed that significant levels of antibody was induced in all vaccinated animals following each booster injection. Western blot of sera from vaccinated macaques confirmed the specific recognition of authentic BV gD. Immune sera were also demonstrated to contain neutralizing activity against infectious BV. Weak lymphoproliferative responses were also observed in vaccinated macaques using recombinant HSV1 gD as a stimulating antigen and flow cytometry analysis of one individual revealed the presence of HSV1 gD-responsive effector T cells. Thus, the BV gD DNA vaccine was demonstrated to induce both humoral and cellular immune responses in macaques which recognized BV gD.

Animals↗

PubMed2002

Endocrine correlates of rank, reproduction, and female-directed aggression in male Japanese macaques (Macaca fuscata).

Fecal testosterone and cortisol levels in six wild male Japanese macaques (Macaca fuscata), three of high rank and three of low, were analyzed to investigate the hormonal correlates of rank, reproduction, and female-directed aggression. The study encompassed the 6-month mating season, from October 1999 to March 2000, during which time 251 fecal samples and approximately 550 h of behavioral data were collected. Dominant males were not found to differ from subordinate males in overall rates of aggressive or copulatory behavior. Likewise, testosterone excretion, which peaked in the early part of the mating season and declined gradually thereafter, did not differ significantly by rank. High-ranking males, however, were observed to excrete significantly higher levels of cortisol than low-ranking males, suggesting that dominance may carry costs. The two hormones were found to be inversely correlated in the two most dominant males, but independent in all others. Rate of noncontact aggression was significantly correlated with testosterone, while no significant relationships were observed between testosterone and contact aggression nor any aspect of copulatory behavior. These data further support the contention that social subordinance and stress are not inexorably linked, as well as suggest that elevated glucocorticoid concentrations in high-ranking males may reflect increased metabolic costs associated with dominant male reproductive strategy.

Aggression↗