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Biomedical subjects

K Tomiyama

Publications and source records attributed to K Tomiyama.

49 records · Page 3Linked to original sources
PubMed1993

YM-09151-2 but not l-sulpiride induces transient dopamine release in rat striatum via a tetrodotoxin-insensitive mechanism.

The effects of the selective dopamine D2 receptor antagonists YM-09151-2 and l-sulpiride on the in vivo release of dopamine (DA), L-3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) in rat striatum were investigated. The drugs were injected into the striatum through a microinjection needle attached to a dialysis probe. YM-09151-2 (0.1 or 1.0 microgram/0.5 microliter) injected into the striatum produced a dramatic rapid-onset transient increase in striatal DA release in a dose-dependent manner. However, the DA increase induced by l-sulpiride (15 or 75 ng/0.5 microliter) was small and of slower onset. An increase of DOPAC levels by YM-09151-2 was biphasic: The first peak occurred at 40 min, followed by a delayed-onset gradual increase. Slower-onset gradual increases were also found in DOPAC levels after l-sulpiride injection and in HVA levels after injections of both YM-09151-2 and l-sulpiride. The infusion of tetrodotoxin (TTX; 2 microM) revealed two different types of DA release mechanisms: The rapid-onset transient DA release induced by YM-09151-2 was TTX insensitive, whereas the slower-onset DA release induced by l-sulpiride was TTX sensitive. Moreover, the rapid-onset transient DA release was Ca2+ independent and was not affected by pretreatment with l-sulpiride or nomifensine. Therefore, it is concluded that YM-09151-2 injected into the striatum produced a transient striatal DA release that is independent of D2 receptors and the action potential.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1991

Functional interaction between dopamine D1 and D2 receptors in rat jaw movements.

The functional interaction between dopamine D1 and D2 receptors in dopamine-mediated jaw movements was studied in ketamine-anaesthetized rats after C1 spinal transection. Jaw movements were recorded by means of a light-emitting diode attached to the mandible; the method permits a detailed qualitative and quantitative analysis of jaw movements. D1 stimulation with SKF38393 (10 mg/kg i.v.) produced frequent bursts of teeth chattering, which were abolished by pretreatment with SCH23390 (0.25 mg/kg i.v.). D2 stimulation by quinpirole (1-10 mg/kg i.v.) produced infrequent bursts of jaw movements, which were characterized by low frequency jaw opening and closure movements from the rest position of the jaw, and absence of tongue protrusions. An additional stimulation of D1 receptors by giving SKF38393 30 min later produced an almost continuous pattern of jaw openings but less closure movements from the rest position, and the openings were accompanied by frequent tongue protrusions. These results clearly demonstrate that the type of oral behaviour produced by stimulation of D1 and D2 receptors together is qualitatively different from that produced by stimulation of either D1 or D2 receptors alone.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1990

Effects of dopamine D1 and D2 agonists and antagonists injected into the nucleus accumbens and globus pallidus on jaw movements of rats.

The effects of bilateral injections of selective D1 and D2 agonists and antagonists into the anteromedial part of the nucleus accumbens and the globus pallidus on apomorphine-induced jaw movements were studied in ketamine-anaesthetized rats after C1 spinal transection. Both SCH 23390 (0.1 and 1 micrograms) and 1-sulpiride (5 and 25 ng) injected into the nucleus accumbens suppressed the display of jaw movements after apomorphine (0.5 mg/kg i.v.). Injection of 1-sulpiride (5 and 25 ng) into the globus pallidus also blocked the effect of apomorphine, whereas SCH 23390 (1 microgram) injected into the same site was ineffective in this respect. Simultaneous application of the selective D1 and D2 agonists, SKF (1 or 5 micrograms) + quinpirole (10 micrograms), into the nucleus accumbens strongly potentiated the effect induced by local administration of each drug alone; a comparable, but smaller, effect was seen after simultaneous injections of these agents into the globus pallidus. These results show that dopaminergic mechanisms within the nucleus accumbens are involved in apomorphine-induced jaw movements, and that the expression of these movements requires concurrent activation of D1 and D2 receptors.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1990

Dopamine D-1 but not D-2 receptor stimulation of the dorsal striatum potentiates apomorphine-induced jaw movements in rats.

The effects of bilateral injections of selective D-1 and D-2 agonists and antagonists into the dorsal striata on apomorphine-induced jaw movements were studied in ketamine-anaesthetized rats after C1 spinal transection. A phototransducer attached to the lower mandible automatically detected jaw movements. YM-09151-2 (0.2 and 0.5 micrograms) and cis(Z)-flupentixol (0.5 and 1 microgram) injected into the dorsal striatum increased the frequency of jaw movements after apomorphine (0.2 mg/kg i.v.). The effects were prevented by administration of SCH23390 (1 microgram) with YM-09151-2 (0.5 microgram) or cis(Z)-flupentixol (1 microgram). Injection of SCH23390 (1 microgram) alone into the dorsal striatum failed to alter the apomorphine (0.5 mg/kg i.v.)-induced jaw movements. Local application of the selective D-1 agonists, SKF38393 (5 micrograms) and SKF75670 (10 micrograms), into the dorsal striatum potentiated the apomorphine (0.2 mg/kg i.v.)-induced jaw movements, while a D-2 agonist, quinpirole (10 micrograms), injected into the same site attenuated these movements. These data are suggestive of an oppositional D-1: D-2 receptor interaction in the dorsal striatum.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1989

Effects of intrastriatal injections of selective dopamine D-1 and D-2 agonists and antagonists on jaw movements of rats.

The effects of bilateral intrastriatal injections of the selective D-1 and D-2 antagonists, SCH23390 and sulpiride on apomorphine-induced jaw movements were studied in ketamine-anaesthetized rats after C1 spinal transection. A photo-transducer attached to the lower mandible automatically detected jaw movements. Apomorphine (0.2, 0.5 and 1.0 mg/kg i.v.) dose dependently increased jaw movements, an effect prevented by prior administration into the ventral striatum of either SCH23390 (0.1, 0.5 and 1 microgram) or sulpiride (125 ng). To be effective, SCH23390 had to be given less than 30 min before apomorphine whereas sulpiride had to be given earlier. Sulpiride injected into the dorsal striatum potentiated the effects of apomorphine, an action prevented by administering the sulpiride with SCH23390. Local application of the selective D-1 and D-2 agonists, SKF38393 (5 micrograms) and quinpirole (10 micrograms) into sites within the ventral striatum from which repeated jaw movements could be obtained by electrical stimulation, also evoked jaw movements; the effects of combining the two drugs were much greater than the effects of either drug alone.

Animals↗
PubMed1988

Ketamine anaesthesia has no effect on striatal dopamine metabolism in rats.

Striatal levels of dopamine (DA), 3,4-dihydroxyphenylacetic acid and homovanillic acid in rats were not altered for at least 6 h after a ketamine injection (100 mg/kg). Striatal DA turnover which was measured by giving alpha-methyl-p-tyrosine after ketamine was unchanged. Even the dose regimen of ketamine which anaesthetized animals for approximately 3.5 h (100 mg/kg + 5 maintenance injections of 50 mg/kg at 30 min intervals) produced no alteration in DA turnover for at least 9 h. These results suggest that ketamine anaesthesia will not adversely affect studies investigating central DAergic mechanisms in rats.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Sulpiride injection into the dorsal striatum increases methamphetamine-induced gnawing in rats.

Sulpiride injected into the dorsal striatum enhanced both methamphetamine- and apomorphine-induced gnawing but blocked both when injected into the ventral striatum. The hyperlocomotion produced by methamphetamine was reduced by sulpiride injected into the dorsal striatum. The DA, DOPAC and HVA concentrations in the ventral striatum were increased 60 min after the injection of sulpiride into the dorsal striatum. Possible reasons for the enhancement of methamphetamine-induced gnawing by sulpiride injected into the dorsal striatum are discussed.

Animals↗
PubMedDate not supplied

Glomangioma in the nasal cavity and paranasal sinuses.

The glomangioma is a hyperplastic lesion of the glomus body. This uncommon tumor is seldom located in the nasal cavity or paranasal sinuses. We present what is to our knowledge the eleventh documented case of an intranasal glomangioma. The differential diagnosis of this lesion, its symptoms, pathogenesis and therapy are discussed. Complete excision is normally curative for this tumor.

Adult↗
PubMedDate not supplied

A rare case of recurrent alpha-fetoprotein-producing gastric cancer without re-elevation of serum AFP.

We report an extremely rare case of recurrent alpha-fetoprotein (AFP)-producing gastric cancer without re-elevation of serum AFP. The patient was a 78-year-old woman with AFP-producing gastric cancer, a rare type of gastric adenocarcinoma. A Borrmann III gastric tumour was surgically resected and AFP-producing gastric cancer was diagnosed based on high levels of serum AFP (705.44 ng/ml) and immunohistochemical examination of the tumour. The serum AFP level decreased to the normal range after resection without any sign of recurrence by imaging, but the patient developed local recurrence of the cancer and died 13 months after surgery. No re-elevation of serum AFP levels was observed after recurrence. Although serum AFP levels are believed to be useful for follow-up in the post-operative period, the possibility that serum AFP levels do not always correlate with the extent of the cancer should be kept in mind.

Adenocarcinoma↗