Cytochrome P450 2B1 immunoreactivity in bronchiolar and alveolar epithelial cells after exposure of rats to ozone

Pulmonary cytochrome P450 (P450) plays an important role in the metabolism of xenobiotics. We have previously demonstrated that exposure to ozone (O3), a major oxidant of photochemical smog, increases P450 content and xenobiotic metabolizing activities in the rat lung. Therefore, it is conceivable that O3 exposures modify the pattern and potency of xenobiotic metabolism. The aim of this study is to examine the effect of O3 exposure on localization of P450 in the lung. After exposure of rats to 0.4 ppm O3 for 14 days, the concentration of P450 2B1, the main isozyme of P450 in the lung, increased to 214% of the control value. By immunohistochemical analyses, O3 exposure caused hypertrophy and hyperplasia of P450 2B1-positive non-ciliated bronchiolar epithelial (Clara) cells, showing an increase in the cell number to 128% of the control level. At the proximal alveoli, O3 exposure induced hypertrophic epithelial cells that presented immunoreactivity to P450 2B1 and morphological characteristics of both type 1 and type 2 cells. These hypertrophic cells had lamellar inclusion bodies, microvilli, and extended cytoplasm. Typical type 2 cells did not react with anti-P450 2B1 antibody even after O3 exposure. These data suggest that O3 exposure may activate the P450-mediated xenobiotic metabolism in the pulmonary epithelial cells, and that expression of P450 2B1 in the pulmonary epithelial cells might be regulated by the factors involved in the process of the differentiation from type 2 to type 1 cells.

[The detection of GLUT2 gene mutation by polymerase-chain reaction single stranded conformation polymorphism (PCR-SSCP) method]

The polymerase chain reaction-single stranded conformation Polymorphism (PCR-SSCP) procedure was applied to examine whether the mutation in the liver/islet glucose transporter (GLUT2) gene could be associated with non-insulin-dependent diabetes mellitus (NIDDM) in Japanese. Samples were processed through 30-40 cycles of 1 min denaturation at 94 degrees C, 1 min annealing at 55-68 degrees C for 1-2 min, extention at 72 degrees C for 1 min, and denaturation at 94 degrees C for 1 min. We identified a silent mutation in codon 479 for PheTTT/TTC.

Serological survey of HIV-1, HIV-2 and human T-cell leukemia virus type 1 for suspected AIDS cases in Ghana

OBJECTIVE

To determine seroprevalence among suspected AIDS patients in Ghana in relation to clinical manifestations.

MATERIALS AND METHODS

Blood samples and medical records were collected from 290 Ghanaian patients with suspected AIDS in 1990 and 1992. Seroprevalence of HIV-1, HIV-2 and human T-cell leukemia virus (HTLV-1) were investigated by the particle agglutination method, indirect immunofluorescence assay, the monoepitope enzyme-linked immunosorbent assay and Western blot.

RESULTS

The specimens were classified into five serologic categories: 78 were HIV-1-positive (26.9%), 25 were HIV-2-positive (8.6%), 17 dual-positive (5.9%), 16 indeterminate (5.5%) and 154 seronegative (53.1%). No significant difference was found between the clinical symptoms of patients with HIV-1 and HIV-2 infection. Of the patients, 14 (4.8%) were HTLV-1-seropositive, of whom 11 were also HIV-positive, indicating a significant correlation between the two groups of viral infections (P < 0.01). However, there was no evidence of an increase in severity of symptoms in cases of dual infection with HTLV-1 and HIV.

CONCLUSIONS

HIV-1 infection is now dominant in Ghana in contrast to our previous survey in 1986 which showed the dominance of HIV-2. The change in seroprevalence suggests that an HIV-1 epidemic has been developing in recent years in this country, where HIV-2 was originally endemic. A relatively high prevalence of dual-reactive specimens implies the existence of highly cross-reactive strains of HIV or frequent coinfection with HIV-1 and HIV-2 in the region. The large number of seronegative patients with clinically diagnosed AIDS raises the question of the inadequacy of AIDS definitions based on clinical manifestations only.

[The frequent areas, risk-factors and protective methods for the fracture in osteoporosis]

Fracture in osteoporosis frequently occurs in the vertebrae, proximal ends of the femur and humerus, and distal end of the radius, in which bone has a thin cortex and much marrow. Aside from various risk-factors for osteoporosis, which are natural risk-factors, risk of falling down (disturbance of mortility and equilibrium, dementia), remodeling of the trabeculae under a state of lack of bone mineral and unequal weight-bearing, slenderness (emaciation), and an inherited status must be included. Therapeutic exercise is desirable for prevention of osteoporotic fracture, because it is effective for against reduction of a bone mineral and prevention of falling and it more over reproduce weight-bearing trabeculae well.

Adriamycin-Fe(3+)-induced inactivation of rat heart mitochondrial creatine kinase: sensitivity to lipid peroxidation

Adriamycin (ADM)-Fe3+ caused inactivation of rat heart mitochondrial creatine kinase (CK) with lipid peroxidation. Superoxide dismutase, catalase and hydroxyl radical scavengers were without effect on the CK inactivation and the lipid peroxidation induced by ADM-Fe3+, indicating the lack of involvement of superoxide, hydrogen peroxide or hydroxyl radicals in these reactions. The antioxidant butylated hydroxytoluene strongly inhibited not only lipid peroxidation but also CK inactivation, indicating that mitochondrial CK was inactivated with lipid peroxidation. Reduced glutathione and dithiothreitol (DTT) prevented CK inactivation without inhibiting lipid peroxidation. The CK activity of 5,5'-dithiobis-(nitorobenzoic acid)-treated mitochondria exposed to ADM-Fe3+ was partially reversed by addition of DTT, indicating that CK inactivation was due to oxidative damage of sulfhydryl groups. In contrast, mitochondrial protein SH groups were not attacked via ADM-Fe(3+)-induced lipid peroxidation. Thus, the SH groups in mitochondrial CK are very susceptible to ADM-Fe(3+)-induced lipid peroxidation.

[A case of gastric cancer completely responding to sequential methotrexate and 5-fluorouracil therapy]

A case of an 81-year-old male with Borrmann II type was reported. The lesion was diagnosed histologically as undifferentiated adenocarcinoma. Biochemically modulated chemotherapy preceded by administration of Methotrexate (MTX) and followed by 5-fluorouracil (5-FU) was given to him. The procedure was weekly intermediate-dose therapy consisting of MTX 100 mg (i.v.) followed 3 hours later by 5-FU 600 mg (i.v.) with leucovorin rescue in the following 2 days. After this treatment was repeated 6 times, advanced gastric cancer disappeared on endoscopic and histological findings, so the patient was regarded as showing a complete response. Ths, this biochemically modulated chemotherapy was thought to be in effective method against gastric cancer.

Subtype analysis of HTLV-1 in patients with HTLV-1 uveitis

The hypothesis that HTLV-1 uveitis, a recently identified disease entity associated with human T-cell leukemia virus type I (HTLV-1), is caused by a specific subtype of the virus was tested. The nucleotide sequences of the long terminal repeat of HTLV-1 from five patients with HTLV-1 uveitis (HU) and four with adult T-cell leukemia were phylogenetically analyzed. Our results showed that both subtypes which had been identified in Japan were associated with HU, indicating that there was no difference in pathogenicity between these phylogenetic subtypes. One of the subtypes was more frequently isolated in Okinawa than in Kyushu, suggesting a bias in the prevalence of each subtype among the inhabitants of these two areas of Japan.

Tyrosine phosphorylation and activation of Bruton tyrosine kinase upon Fc epsilon RI cross-linking

Tyrosine phosphorylation of several cellular proteins is one of the earliest signaling events induced by cross-linking of the high-affinity receptor for immunoglobulin E (Fc epsilon RI) on mast cells or basophils. Tyrosine kinases activated during this process include the Src family kinases, Lyn, c-Yes, and c-Src, and members of another subfamily, Syk and PTK72 (identical or highly related to Syk). Recently, some of us described two novel tyrosine kinases, Emb and Emt, whose expression was limited to subsets of hematopoietic cells, including mast cells. Emb turned out to be identical to Btk, a gene product defective in human X-linked agammaglobulinemia and in X-linked immunodeficient (xid) mice. Here we report that Fc epsilon RI cross-linking induced rapid phosphorylation on tyrosine, serine, and threonine residues and activation of Btk in mouse bone marrow-derived mast cells. A small fraction of Btk translocated from the cytosol to the membrane compartment following receptor cross-linking. Tyrosine phosphorylation of Btk was not induced by either a Ca2+ ionophore (A23187), phorbol 12-myristate 13-acetate, or a combination of the two reagents. Co-immunoprecipitation between Btk and receptor subunit beta or gamma was not detected. The data collectively suggest that Btk is not associated with Fc epsilon but that its activation takes place prior to protein kinase C activation and plays a novel role in the Fc epsilon RI signaling pathway.

[A case report of reconstructive operation in traumatic tricuspid regurgitation]

Tricuspid regurgitation due to non-penetrating trauma occurred in a 21-year-old male patient who had received chest trauma in a motorcycle accident. Echocardiography demonstrated prolapse of the tricuspid anterior leaflet into the right atrium and massive tricuspid regurgitation. He was diagnosed as traumatic tricuspid regurgitation from his past history of the trauma. A reconstructive operation was performed successfully 4 years after the trauma. The chordal rupture of the anterior tricuspid leaflet was repaired using PTFE suture and annuloplasty of the dilated annulus was made using Carpentier ring. Tricuspid regurgitation was completely repaired as shown by the postoperative echocardiogram.

Downsizing of valve allografts for use as right heart conduits

In recent years, there has been a worsening shortage of small and intermediate-sized aortic and pulmonary allografts for use as right ventricular-to-pulmonary artery conduits in infants and children. However, there is a surfeit of large pulmonary and aortic allografts from adult donors. The feasibility of reducing a large allograft to a more useful size was examined using human pulmonary and aortic allografts. Eleven pulmonary allografts (11 to 26 mm in diameter) and nine aortic allografts (5 to 27 mm in diameter) were studied. Valve competence before downsizing was tested with a column of saline to a static pressure equivalent to the normal pulmonary pressure (20 mm Hg). Regurgitant flow was measured for 15 minutes. One complete cusp of the valve was excised, together with a longitudinal strip of the arterial wall. A bicuspid valved conduit was created by suturing the allograft longitudinally. The diameter of the bicuspid valve was measured with a dilator. A nomogram was constructed that predicts the size of the bicuspid allograft based on the size of the original allograft. The competence of the bicuspid allograft was tested and the regurgitant flow was compared with that of the original tricuspid allograft. The transvalvular systolic pressure gradient was measured with the bicuspid allograft placed in a pulsatile extracorporeal perfusion circuit at a flow rate of 1 L/min and a mean pressure of 20.5 +/- 2.6 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphological changes of somatostatin neurons in the suprachiasmatic nucleus by hypophysectomy of the rat

After hypophysectomy, behavioral circadian rhythmicities in the rat became indistinct and phase shift was observed. Therefore, it was thought that the suprachiasmatic nucleus (SCN), which is the circadian oscillator in mammals, was affected by hypophysectomy. We investigated the effects of hypophysectomy on SCN neurons using immunohistochemical staining. Wistar-Imamichi strain male rats were hypophysectomized at 60 days old. Their brains were fixed by acrolein perfusion at 10, 30 and 60 days after the operation, and then vasopressin (AVP)-, vasoactive intestinal polypeptide (VIP)- and somatostatin (SRIH)- neurons in the SCN were stained immunohistochemically. Ten days after the operation, SRIH-neurons were not found in the SCN. At 30 and 60 days after the operation, a few SRIH-positive cell bodies were recognized. In contrast, AVP- and VIP- neurons did not change in morphology in comparison with normal rats. These results suggest that hypophysectomy produces an essential change in SRIH neurons in the SCN, and that such change is responsible for the abnormal behavioral rhythms.

Thyroid hormone concentrations in the gonads of wild chum salmon during maturation

Changes in gonadal and plasma concentrations of thyroid hormones were examined at various stages of maturation in chum salmon (Oncorhynchus keta) caught in the Bering Sea and the Bay of Alaska. Plasma concentrations of thyroxine (T4) were less than 5 ng ml(-1), and those of 3,5,3'-triiodo-L-thyroxine (T3) were less than 2 ng ml(-1) I in both males and females, regardless of the degree of sexual maturity or the gonadosomatic index (GSI).There was no clear relationships between circulating thyroid hormone levels and tissue levels. The ovarian T4 concentrations were undetectable (less than 0.2 ng g(-1)) or less than 2 ng g(-1) when GSI was lower than 1%, but increased thereafter and reached a plateau of 8-10 ng g(-1) when GSI became 2%. The ovarian T3 concentrations were about 5 ng g(-1) when GSI was 1%, increased to a maximum level (20 ng g(-1)) when GSI was about 2%, and decreased to a constant level of 10 ng g(-1) thereafter. The T4 and T3 content in single oocyte increased proportionally to the oocyte volume, indicating a constant incorporation of the hormones into the oocyte.The T4 concentrations in the testis were 1 ng g(-1) or less regardless of the GS1. On the other hand, the T3 concentrations were highest (15 ng g(-1)) when the GSI was less than 1%, decreased thereafter when spermatocytes appeared in the testis, and became about 5 ng g(-1) I in testes containing spermatozoa, raising the possibility of a role for T3 during early gamete and/or gonad maturation of testes.

3',3",5',5"-Tetraiodophenolsulfonephthalein is a selective inhibitor of Ca(2+)-pumping ATPase in intracellular Ca2+ store

3',3",5',5"-Tetraiodophenolsulfonephthalein (I4PSP) stimulated both Ca2+ transient levels and aggregation in response to thrombin in platelets. Ca2+ uptake into skeletal sarcoplasmic reticulum (SR) was inhibited by I4PSP (IC50, 1.8 microM) whereas that of red blood cell ghosts was not affected by it. Furthermore, I4PSP inhibited the SR Ca(2+)-ATPase activity (IC50, 1.1 microM). Kinetic analysis of the inhibitory effects of I4PSP reveals that I4PSP shows an inhibition of noncompetitive and competitive type with respect to low and high concentrations of ATP, respectively. The mode of inhibition by I4PSP is an uncompetitive type with respect to Ca2+. I4PSP decreased the decomposition rate of the phosphorylated enzyme intermediate (EP). The change in the tryptophan fluorescence of SR Ca(2+)-ATPase induced by ATP was reduced by I4PSP indicating inhibition of the EP transition from Ca2E1P to E2P. The concentration-inhibitory response curves for I4PSP in Ca(2+)-ATPase activities and fluorescence changes were closely correlated. These results suggest that I4PSP slows down the structure transition from Ca2E1P to E2P, resulting in inhibition of the Ca(2+)-ATPase activity. On the basis of these results, it is suggested that the stimulation of Ca2+ transient levels in platelets and their aggregation in response to thrombin are due to the inhibition of Ca2+ pump in intracellular Ca2+ stores by I4PSP.

Characterization of cell phenotype by a novel cDNA library subtraction system: expression of CD8 alpha in a mast cell-derived interleukin-4-dependent cell line

We have established a unique variant cell line, MC/9.IL-4, which continuously proliferates in the presence of interleukin-4 (IL-4), from a murine interleukin-3 (IL-3)-dependent mast cell line, MC/9 (referred to as MC/9.IL-3). Compared with MC/9.IL-3 cells, MC/9.IL-4 cells are smaller, lack cytoplasmic granules and metachromasia, carry a very small amount of histamine, and express fewer high-affinity IgE receptors (IgERs) and IL-3 receptors. To further characterize MC/9.IL-4, we developed a novel method to enrich cell type-specific cDNAs by cDNA library subtraction and applied it for MC/9.IL-3 versus MC/9.IL-4. Sequence analysis of cDNA clones isolated by this technique showed that MC/9.IL-4 cells specifically express CD8 alpha and expression of mast cell-specific proteases and major histocompatibility complex class II (MHCII) is considerably decreased. It was also noted that responsiveness to the IL-3-agonistic antibody F9 and expression of the transcription factor GATA-2 is diminished in MC/9.IL-4, indicating that MC/9.IL-4 have lost major characteristics of the bone marrow-derived cultured mast cells. Because other T-cell marker antigens, CD8 beta, CD4, Thy-1, were not detected on MC/9.IL-4 cells, MC/9.IL-4 cells may represent an unknown class of hematopoietic cells that express CD8 alpha. This cell line will be useful in studies of IL-4-mediated signal transduction, as well as transcriptional regulation of mast cell characteristic genes. This study also demonstrates the effective use of the cDNA library subtraction strategy to characterize unknown types of hematopoietic cells at the molecular level.

Structural polymorphism of telomere DNA: interquadruplex and duplex-quadruplex conversions probed by Raman spectroscopy

The solution secondary structures and nucleotide conformations in the telomeric DNA of Oxytricha nova have been determined by Raman spectroscopy. Structural polymorphism is demonstrated for both single-stranded [d(T4G4)4] and double-stranded [d(G4T4G4).d(C4A4C4)] telomere models. In the case of d(T4G4)4, which is a prototype for the single-stranded telomeric tail, an interquadruplex equilibrium involving parallel and antiparallel strand configurations is shown to be governed by the solution concentrations of both Na+ and K+. In both the parallel and antiparallel quadruplexes of d(T4G4)4, the local geometry of the phosphodiester backbone is similar to that of canonical B DNA, and associations between bases of the guanine quartet involve Hoogsteen hydrogen bonding. However, the deoxyguanosine (dG) sugar conformations are significantly different in the two quadruplexes. In the extended parallel form, dG residues assume only the C2'-endo/anti conformation with respect to deoxyribose pucker and glycosyl orientation. In the foldback antiparallel form, dG residues are distributed equally between C2'-endo/anti and C2'-endo/syn conformations. In the case of d(G4T4G4).d(C4A4C4), which serves as a model for the double-stranded B DNA regions of Oxytricha telomeres, we show that disproportionation of the B form duplex to yield stable parallel quadruplexes of the guanine-rich strand occurs reversibly at high solution concentrations of either Na+ or K+. The present study reveals that both interquadruplex and duplex-quadruplex conversions of Oxytricha telomeric DNA are under the control of an alkali cation switch.(ABSTRACT TRUNCATED AT 250 WORDS)

Design of variants of the second domain of urinary trypsin inhibitor (R-020) with increased factor Xa inhibitory activity

The second domain (R-020) of human urinary trypsin inhibitor (UTI) exerts similar inhibitory activities on trypsin, alpha-chymotrypsin, leukocyte elastase, and plasmin to those of UTI itself, and additionally inhibits coagulation factor Xa (FXa) and plasma kallikrein, on both of which UTI has no inhibitory effect. In the present study, we attempted to increase this FXa-inhibitory activity by modeling the structure of R-020-FXa complex and substituting one or two amino acids in R-020 using recombinant DNA technology. Molecular modeling of R-020 and FXa was performed with reference to X-ray analysis of the complex of bovine pancreatic trypsin inhibitor (BPTI) and bovine trypsin to determine the site of amino acid modification. The expression plasmids into which R-020 genes with base substitution were inserted were prepared and introduced into Escherichia coli to express R-020 variants. The resulting variants were purified and their enzyme inhibitory activities were measured. The FXa-inhibitory activity was increased in four variants with single amino acid substitution. With another four variants having two amino acid substitutions involving combinations of the above single amino acid substitutions, the FXa-inhibitory activity was further increased. Because the electrostatic interaction within R-020-FXa complex seemed stronger in these R-020 variants, this increase in FXa-inhibitory effect was speculated to be a consequence of more potent binding between the enzyme and the inhibitor.

The position of symbrachydactyly in the classification of congenital hand anomalies

The clinical features of 53 cases of intercalated hypoplasia and 113 cases of distal aplasia are reviewed and compared with each other and with 129 cases of syndactyly. Tri-, di- and mono-phalangeal symbrachydactyly, and adactyly with nubbin digits are consecutive anomalies. Transverse deficiency may result if the mesenchyme is damaged severely, and if damage is mild and formation has continued, intercalated transverse deficiency may occur. Webbing in symbrachydactyly may result from failure of the apical ectodermal ridge under the influence of damaged mesenchyme.

Recent fertility decline in Dariusleut Hutterites: an extension of Eaton and Mayer's Hutterite fertility study

A church book that has been routinely updated by the Dariusleut Hutterites enabled us to update some fertility tables presented by Eaton and Mayer in the 1950s. The age-specific (nuptial) fertility rates and the total fertility rates (TFRs) were calculated for every 5-year period from 1901-1905 to 1981-1985. Our calculations for Dariusleut, one of the three sects of the Hutterites, gave slightly lower age-specific nuptial fertility rates before 1951 compared with the figures given by Eaton and Mayer (1953) for all Hutterites in the corresponding time periods. The recent decline in Hutterite fertility, especially at higher maternal ages, was confirmed in this study. The TFR, given as a sum of 5-year-grouped age-specific nuptial fertility rates from 15 to 49 years of maternal age, was higher (8.80-9.83) in the years 1946-1965, but it declined to 8.13 in 1966-1970, to 7.22 in 1971-1975, to 6.39 in 1976-1980, and to 6.29 in 1981-1985. For the age groups 35-39 years and older the age-specific nuptial fertility rate in 1981-1985 decreased by more than 50% compared with the rate during the peak period of 1951-1955. The probability of a married woman having a live birth at each age from 15 to 49 years still peaked around the twentieth year of life, as found by Eaton and Mayer (1953), but it decreased more rapidly from the late twenties among the recently married women, most evidently in their thirties.

Schedule-intensified M-VAC chemotherapy for advanced urothelial cancer with recombinant human granulocyte colony stimulating factor (rhG-CSF)

M-VAC (Methotrexate, vinblastine, adriamycin and cisplatin) combination systemic chemotherapy is useful for treating invasive or metastatic transitional cell carcinoma. Granulocytopenia is the major dose-limiting factor of this chemotherapy and it takes 4 weeks or more to complete a single course of M-VAC. We have tried to shorten the period of M-VAC chemotherapy from 4 to 3 weeks by using rhG-CSF. With this modified M-VAC regimen, the number of days on which the absolute neutrophil count was less than 1000/mm3 was significantly reduced and the period to reach the neutropenia nadir was shortened. No severe side-effects were observed. In all patients treated with 2 courses of this modified M-VAC short regimen, the period of hospitalization could be reduced by 2 weeks. We emphasize the possibility of shortening the M-VAC regimen.

Detection of stromelysin in synovial fluid and serum from patients with rheumatoid arthritis and osteoarthritis

Stromelysin levels were measured using a one-step sandwich immunoassay in synovial fluid (SF) obtained from 31 patients with rheumatoid arthritis (RA) (31 samples) and 13 patients with osteoarthritis (OA) (13 samples) and in serum from 81 patients with RA (106 samples), 12 with OA (14 samples), 12 with gouty arthritis (gout) (14 samples), and 8 with osteoporosis (OP) (14 samples) to identify differences in the levels in these diseases as well as correlations with clinical parameters in RA. SF stromelysin levels were significantly higher in RA than in OA, and rose with increasing joint destruction in the former. No significant correlations were found between the SF stromelysin level in RA and various clinical parameters, except for the volume of SF which showed a correlation. Serum levels of stromelysin were highest in RA, gout, OA, and osteoporosis in decreasing order, and in RA were correlated with the Steinbrocker Stage. A significant correlation was also found between the serum stromelysin level and number of swollen joints, and correlations with the Lansbury index, ESR, CRP, WBC and Plt. The stromelysin level in SF was thought to be a useful parameter of local joint involvement and that in serum of the severity of systemic joint inflammation.

Relative glucocorticoid potency revisited

To determine the relative potency of synthetic glucocorticoids, glucocorticoid receptor expressing cells were transfected with a hormone-inducible reporter gene, and were cultured in the presence of various glucocorticoid ligands. Hormonal inducibility was determined by means of a chloramphenicol acetyltransferase assay. Dexamethasone and prednisolone, as well as cortisol, induced the expression of the reporter gene in a dose-dependent fashion. The relative potency of each ligand was in this order when inducibility was quantitatively assessed. In conclusion, the transcription assay described here may be a convenient and alternative method to evaluate the relative potency of given glucocorticoids.

Stereotyped behavioral responses to an auditory stimulus in the course of repeated treatment with methamphetamine plus scopolamine and methamphetamine in rats

The present experiment was designed to study the effects of an auditory stimulus with 300 Hz, 100 dB on gradual emergence of behavioral sensitization in the course of repeated administration of methamphetamine (MAP) in combination with scopolamine (SCOP) and MAP. Repeated intraperitoneal injection of MAP (4.0 mg/kg) plus SCOP (0.5 mg/kg) induced significantly progressive and enduring enhancement of stereotyped behavior, resulting in intense, focussed stereotypy intermingled with gnawing and licking compared to repeated MAP treatment. Vigorous stereotyped behavior induced by repeated MAP plus SCOP was progressively attenuated by the tone, resulting in attenuation of the development of behavioral sensitization. Conversely, the tone had no invariable effects on behavioral sensitization induced by repeated MAP treatment. The present findings indicate that repeated MAP plus SCOP treatment progressively induced attenuating effects of tone as low as 300 Hz on MAP plus SCOP-induced intense stereotypy and vigorous behavioral sensitization. These findings suggest that a reciprocal balance between dopaminergic and cholinergic inhibitory systems may be involved in producing behavioral sensitization, and in the attenuating effects of the tone on MAP plus SCOP-induced vigorous behavioral sensitization.