Regional differences in desensitization of c-Fos expression following repeated self-stimulation of the medial forebrain bundle in the rat.

The acute self-stimulation of the medial forebrain bundle was reported to induce the expression of c-Fos, the protein product of c-fos, an immediate early gene, in the central nervous system. In the present study, we examined regional changes in c-Fos expression in several reward-related areas of rat brain in response to short- and long-term exposure to self-stimulation of the medial forebrain bundle. Short-term one-hour stimulation of the medial forebrain bundle for one day after training, which evoked steady self-stimulation behavior, significantly increased the number of c-Fos-positive neurons bilaterally in all of 15 brain structures assayed, as compared to the non-stimulation control. Among them, structures showing a larger number of the stained neurons on the stimulated side were the anterior olfactory nucleus, amygdala, medial caudate-putamen complex, lateral septum, bed nucleus of the stria terminals, ventral pallidum, substantia innominata, lateral preoptic area, medial preoptic area, lateral hypothalamus rostral to the stimulating electrodes, and substantia nigra. Long-term stimulation of the medial forebrain bundle once daily for five successive days, which maintained consistently stable self-stimulation behavior, also increased the number of c-Fos-positive neurons in the aforementioned structures, as compared to the control. However, the long-term rewarding stimulation diminished the increased number of labeled neurons, as compared to the short-term rewarding stimulation. Seven areas, medial caudate-putamen complex, ventral pallidum, substantia innominata, lateral preoptic area, medial preoptic area, rostral lateral hypothalamus and substantia nigra, showed asymmetrical, ipsilateral predominance after the short- and long-term stimulation. However, the stained neuron count in those areas after the long-term stimulation was reduced to less than 50% of that found after the short-term stimulation with the exception of lateral preoptic area and rostral lateral hypothalamus. The results suggest that the development of desensitization of c-Fos response may differ among the reward-relevant brain regions as a consequence of repeated self-stimulation. They also indicate that a larger portion of neurons in the lateral preoptic area and rostral lateral hypothalamus may be implicated in both short- and long-term self-stimulations of the medial forebrain bundle.

Fos expression in neurons immunoreactive for neuronal nitric oxide synthase in the rat paraventricular nucleus after intraperitoneal injection of interleukin-1 beta.

Double immunostaining for Fos and neuronal nitric oxide synthase (nNOS) was used to examine whether nNOS-immunoreactive neurons in the paraventricular hypothalamic nucleus (PVN) are activated to express Fos immunoreactivity by intraperitoneal injection of interleukin-1 beta (IL-1 beta) in the rat. Quantitative analysis revealed that some nNOS-positive PVN neurons are activated by IL-1 beta (4 microg/kg, i.p.) administration, but the majority of the IL-1 beta-activated PVN neurons do not express nNOS and are distributed mainly in the parvocellular part of the PVN.

Methamphetamine-induced Fos expression in the substantia nigra pars reticulata in rats with a unilateral 6-OHDA lesion of the nigrostriatal fibers.

In rats with a unilateral 6-hydroxydopamine (6-OHDA)-induced lesion in the nigrostriatal fibers, methamphetamine (3 mg/kg, i.p.) induced Fos-like immunoreactivity (FLI), which was inhibited by pretreatment with N-methyl-D-aspartate antagonist MK-801 (1 mg/kg, i.p.), not only in the medial striatum contralateral to the lesion but also in the substantia nigra pars reticulata (SNr) ipsilateral to the lesion. Thus, hemispheric asymmetries in FLI were induced by methamphetamine in the medial striatum and the SNr in the 6-OHDA model of turning which may be related to the altered function of glutamatergic transmission.

Methamphetamine induces fos expression in the striatum and the substantia nigra pars reticulata in a rat model of Parkinson's disease.

In rats with a unilateral 6-hydroxydopamine (6-OHDA) lesion in the nigrostriatal pathway, methamphetamine (3 mg/kg, i.p.) induced Fos-like immunoreactivity (FLI) not only in the striatum on the intact side but also in the substantia nigra pars reticulata (SNr) on the lesioned side. The methamphetamine-induced hyperexpression of FLI in the SNr on the lesioned side was suppressed by pretreatment with either dopamine D1 receptor antagonist SCH-23390 (0.5 mg/kg, i.p.), D2 receptor antagonist raclopride (2 mg/kg, i.p.) or N-methyl-d-aspartate receptor antagonist MK-801 (1 mg/kg, i.p.), which was concomitant with inhibition of the methamphetamine-induced rotational behavior of each antagonist. However, the hyperexpression of FLI in the SNr was not suppressed by intrastriatal grafts of fetal ventral mesencephalon which could suppress the methamphetamine-induced rotation completely. These results indicate that opposite hemispheric asymmetries in FLI are induced by methamphetamine in the striatum and the SNr in the 6-OHDA rats. It is suggested that the FLIs in the two discrete sites are activated independently by different mechanisms, and furthermore, different neuronal pathways are involved in the methamphetamine-induced rotation and Fos expression in the SNr of 6-OHDA rats.

Dopaminergic transplants suppress L-DOPA-induced Fos expression in the dopamine-depleted striatum in a rat model of Parkinson's disease.

We examined the effects of MK-801, a non-competitive antagonist of the N-methyl-D-aspartate (NMDA) receptor, and fetal ventral mesencephalic (VM) transplants on L-3,4-dihydroxyphenylalanine (L-DOPA)-induced Fos protein expression in the dopamine (DA)-depleted striatum. Unilateral 6-hydroxydopamine (6-OHDA) lesions of the nigrostriatal pathway were produced in young adult female rats and grafting was performed 3 weeks later. Methamphetamine-induced rotational behavior recovered significantly on the 4th week after grafting. Immunohistochemical examinations of c-Fos and tyrosine hydroxylase (TH) were performed 3-4 months after grafting. L-DOPA (100 mg/kg, i.p.) markedly induced Fos-like immunoreactivity (FLI) in the DA-depleted striatum. Pretreatment with a large dose of MK-801 (3-4.5 mg/kg, i.p.) dose-dependently suppressed L-DOPA-induced FLI in the striatum. The stimulatory effect of L-DOPA on c-Fos expression observed within the lesioned striatum was suppressed by fetal VM transplants. It seemed that the graft-induced effect on FLI extended over a considerably larger area than that covered by the graft-derived TH-immunoreactive innervation. Taken together, these findings suggest that glutamatergic modulation is involved in the L-DOPA-induced c-Fos expression in the denervated striatum which is normalized by fetal VM transplants. It also seems likely that VM grafts suppress the L-DOPA-induced expression of transcriptional factors which might be involved in the mechanisms underlying various side effects of chronic L-DOPA therapy.

Serotonergic activity in the rat striatum after intrastriatal transplantation of fetal nigra as measured by microdialysis.

In vivo microdialysis was used to examine the effects of dopaminergic transplants on extracellular concentrations of dopamine (DA), serotonin (5-HT), and their precursors and major metabolites in the denervated rat striatum. Dialysis perfusates were collected from intact 6-hydroxydopamine (6-OHDA) lesion plus sham grafted, and lesion plus fetal substantia nigra (SN) grafted striata. The SN transplants ameliorated the reduction of striatal DA and dihydroxyphenylacetic acid (DOPAC) levels in rats with unilateral 6-OHDA lesions of the mesostriatal pathway. The transplants also increased extracellular levels of 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) in the denervated striatum. In response to NSD-1015 (an inhibitor of aromatic L-amino acid decarboxylase, AADC), 5-hydroxytryptophan (5-HTP) levels were substantially elevated in the SN grafted striata as compared with those in the sham grafted controls, which continued even after subsequent administration of L-3,4-dihydroxyphenylalanine (L-DOPA, 100 mg/kg i.p.). Immunohistochemical analysis showed hyperinnervation of 5-HT fibers in the grafted striatum, which was consistent with the results of microdialysis experiments. These results indicated that implantation of SN grafts into the 6-OHDA-lesioned striatum of rats induces hyperactivity of 5-HT synthesis, release and metabolism.

Repeated administration of high dose levodopa enhances hydroxyl radical production in the rat striatum denervated with 6-hydroxydopamine.

We examined whether levodopa (L-DOPA) might increase production of hydroxyl radicals in intact and dopamine-denervated rat striatum. Salicylate trapping combined with in vivo microdialysis provided measurements of 2,3-dihydroxybenzoic acid (2,3-DHBA) as a marker of hydroxyl radical production. Acute administration of high-dose L-DOPA (200, 500 mg/kg, i.p.) did not alter 2,3-DHBA levels in intact striatum or in striatum denervated with 6-hydroxydopamine. On the other hand, L-DOPA administration (200 mg/kg, i.p.) transiently increased 2,3-DHBA in dopamine-denervated striatum of rats after repeated administration of L-DOPA (200 mg/kg, i.p., once daily for 16 days). The results indicated that repeated administration of high dose L-DOPA increased production of hydroxyl radicals in dopamine-denervated striatum.

Dopaminergic transplants alter in vivo activity of tryptophan hydroxylase in the striatum in a rat model of Parkinson's disease.

L-3,4-Dihydroxyphenylalanine (L-DOPA) inhibits the activity of tryptophan hydroxylase (TRH) and thus serotonin synthesis. This inhibitory effect of L-DOPA may be related to some side effects in the patients under L-DOPA therapy. The effects of transplantation of fetal ventral mesencephalon (VM) on extracellular 5-hydroxytryptophan (5-HTP) accumulation was examined by microdialysis as an index of in vivo activity of TRH in the striatum of 6-hydroxydopamine (6-OHDA)-lesioned rats. In the rat striatum perfused with m-hydroxybenzylhydrazine (NSD-1015; an inhibitor of aromatic L-amino acid decarboxylase), L-DOPA and 5-HTP in dialysate were measured simultaneously. In response to NSD-1015, 5-HTP levels were substantially elevated in the lesion plus VM-grafted striata as compared with those in the lesion plus sham-grafted striata. The results indicate that implantation of dopamine-rich VM grafts into the 6-OHDA-lesioned striatum of rats induces hyperactivity of TRH.

Peripherally administered tetrahydrobiopterin increases in vivo tryptophan hydroxylase activity in the striatum after transplantation of fetal ventral mesencephalon in six hydroxydopamine lesioned rats.

The intraperitoneal administration of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (6R-BH4), a natural cofactor for tyrosine hydroxylase and tryptophan hydroxylase (TRH), dose-dependently increased the extracellular concentration of 6R-BH4 itself in rat striatum. The concentration was investigated by in vivo microdialysis and measured simultaneously with 5-hydroxytryptophan (5-HTP), a precursor of serotonin, by high performance liquid chromatography with electrochemical detection. The 6R-BH4 (50 mg/kg, i.p.) administration increased the accumulation of 5-HTP as an index of in vivo TRH activity under the inhibition of aromatic L-amino acid decarboxylase by NSD-1015 in the striatum of both normal control and 6-hydroxydopamine lesioned rats with intrastriatal transplants of fetal ventral mesencephalon (VM). The results suggest that TRH in the striatum of both control and VM-grafted rats is activated by 6R-BH4 penetrating into the brain from the blood.

Cellular distributions of AMPA glutamate receptor subunits in fetal ventral mesencephalon transplants in the dopamine-depleted striatum of a rat.

To demonstrate the cellular distributions of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptor subunits (GluR1, GluR2/3, and GluR4) in the intrastriatal grafts of a rat model of Parkinson's disease, immunocytochemistry was performed in 6-hydroxydopamine rats with intrastriatal transplants of fetal ventral mesencephalon (VM). In the fetal VM (at embryonic day 15) in which the tyrosine hydroxylase (TH) immunoreactivity was intensely observed, no GluR subunit immunoreactivity was detected. Within the intrastriatal fetal VM grafts containing TH-positive cells, a large number of cells immunoreactive for GluR1 and GluR2/3 were observed. However, the GluR1- and GluR2/3-positive cells tended to locate homogeneously within the grafts and were composed of various cell sizes and shapes, mainly medium-sized and aspiny cells. Weak GluR4-positive cells were seen in the grafts, although in some cases the staining was too faint to see any immunoreactive cells at all. Double immunostaining revealed that a part of TH-positive cells in the grafts was also immunopositive for GluR1 or GluR2/3. Both dopaminergic neurons and nondopaminergic neurons in the VM transplants appear to be modified functionally by glutamatergic afferents via various glutamate receptors, including GluR1 and GluR2/3 and, to a lesser extent, GluR4.

Temperature effect on serum protein binding kinetics of phenytoin in monotherapy patients with epilepsy.

The effects of temperature on the binding kinetics of phenytoin (PHT) to serum proteins were determined in patients with epilepsy. Serum samples examined in the study were obtained from 59 patients (31 male, 28 female) with epilepsy on PHT monotherapy. Their age ranged from 3 to 64 years (mean (SD), 23.3 (16.3) years). Protein binding of PHT was evaluated by ultrafiltration under current routine laboratory conditions (25 +/- 3 degrees C) or at a temperature of 37 degrees C. The in vivo binding parameters of PHT to serum proteins were determined using a binding equation derived from the Scatchard equation for a one-site binding model. Significant differences were observed in serum concentrations of unbound PHT between paired data (P < 0.05). The mean association constant (K) of PHT to serum proteins is 0.011 microM-1 at 25 +/- 3 degrees C and 0.006 microM-1 at 37 degrees C, while mean total concentration of binding sites (n(Pt)) is 1002 microM for 25 +/- 3 degrees C and 1112 microM for 37 degrees C. Significant differences were observed in the binding kinetics of PHT to serum proteins for the different temperature conditions of ultrafiltration (P < 0.05). Our study confirms that binding affinity for PHT-serum protein interaction is approximately 45% lower at 37 degrees C than at 25 +/- 3 degrees C and consequently, binding potential (K.n(Pt)) is approximately 39% lower at 37 degrees C than at 25 +/- 3 degrees C.

[Simultaneous operation of gastrectomy, cholecystectomy and coronary artery bypass grafting using right gastroepiploic artery].

We present a case who received the simultaneous surgical corrections of unstable angina, acute gastric ulcer, and cholelithiasis. A 72-year-old man was admitted to our hospital due to unstable angina. An emergency coronary angiography was performed and we found severe 2 vessels disease (RCA ostium and proximal LAD lesions). After the admission, the angina was poorly controlled and the surgical treatment had been considered. The patient developed sudden hematemesis due to the uncontrolled bleeding from gastric ulcer. Then the emergency operation was performed. Partial gastrectomy with preservation of RGEA and cholecystectomy were done followed by CABG to RCA with RGEA and to LAD with autologous saphenous vein. The postoperative course was uneventful and the patient is in good condition to date.

Effect of ventricular stretch on contractile strength, calcium transient, and cAMP in intact canine hearts.

Isovolumic contractions were imposed by intraventricular balloon in 39 isolated, blood-perfused canine hearts to investigate the effects of myocardial stretch on contractile force. After stabilization at 37 degrees C, left ventricular volume was increased so that end-diastolic pressure increased from 0 to 5 mmHg. After the immediate increase in developed pressure [DP; from 37 +/- 14 to 82 +/- 22 mmHg (means +/- SD)], there was a slow secondary rise in DP (97 +/- 27 mmHg) that peaked at 3 min. However, DP subsequently decreased over the next 7 min back to the initial value (84 +/- 25 mmHg). Light emission from microinjected aequorin (n = 10 hearts) showed that changes in intracellular calcium [3 min: 124 +/- 15% (P < 0.01); 10 min: 99 +/- 18% of baseline] paralleled DP changes. Increases in myocardial adenosine 3',5'-cyclic monophosphate (cAMP) content (n = 12) accompanied the secondary rise in DP. In contrast, the gradual elevation of DP after the stretch was not exerted during continuous beta-adrenergic stimulation by isoproterenol. Thus, in contrast to isolated muscle, stretch only transiently increases intracellular calcium and contractile strength in intact hearts. The findings of changes in cAMP and abolition of the phenomena by beta-stimulation suggest that a primary stretch-mediated influence on cAMP metabolism may underlie these phenomena.

Left-to-right systolic and diastolic ventricular interactions are dependent on right ventricular volume.

Three-compartment elastance modeling predicts that the magnitude of gain is solely dependent on the ratio of free wall and septal elastances. However, when nonlinearities in pressure-volume relationships are considered, the same model predicts that gain is load dependent. We therefore studied left-to-right ventricular interactions in the isolated cross-perfused canine heart preparation to determine whether, in fact, right ventricular volume modulates left-to-right ventricular interaction. We found that left-to-right systolic gain increased from 0.035 +/- 0.022 to 0.073 +/- 0.017 (P = 0.003) and left-to-right diastolic gain increased from 0.067 +/- 0.050 to 0.186 +/- 0.097 (P = 0.03) in response to increased right ventricular volume. This degree of volume dependency of gain is predicted by the three-compartment model when measured nonlinearities in time-varying elastance are taken into account. Future studies will need to account for changes in loading conditions when interpreting changes in systolic and diastolic interactions.

Effects of the new cardiotonic phosphodiesterase inhibitor 1,2-dihydro-5- imidazo[1,2-a]pyridin-6-yl-6-methyl-2-oxo-3-pyridine-carbonitrile hydrochloride monohydrate on aortic input impedance.

Beneficial effects of cardiotonic phosphodiesterase inhibitors on congestive heart failure are possibly mediated in part by a reduction of afterload. 1,2-Dihydro-5-imidazo[1,2-a]pyridin-6-yl-6-methyl-2-oxo-3- pyridinecarbonitrile hydrochloride monohydrate (E-1020, CAS 119615-63-3), a new cardiotonic phosphodiesterase inhibitor was evaluated for its effect on aortic input impedance in eight anesthetized open-chest dogs. First instantaneous aortic pressure and flow under random ventricular pacing before and after E-1020 infusions (10, 30, and 100 micrograms/kg i.v.) were measured. Then aortic input impedance over the frequency range of 0.024 to 20 Hz was estimated using a multichannel autoregressive model. With the infusion of E-1020, aortic input impedance was decreased in the low frequency range (below 0.1 Hz) and shifted leftward in the transitional frequency range (from 0.1 to 2 Hz), while it remained unchanged in the high frequency range (above 2 Hz). Parameterization of the aortic input impedance using a three-element Windkessel model indicated that E-1020 (at a dose of 100 micrograms/kg i.v.) decreased arterial resistance by 35% (p less than 0.01) and increased arterial compliance by 12% (p less than 0.01). It is concluded that E-1020 improves cardiac performance by unloading static and dynamic afterload in addition to its cardiotonic effect.

Random exercise stress test in diagnosing effort angina.

To improve the performance of exercise stress testing in the diagnosis of effort angina while minimizing risks of serious complications, we evaluated an impulse response of ST changes, which is a transient ST response resulting from a hypothetical, strenuous-impulselike exercise, without actually imposing the strenuous load. To obtain the impulse response, subjects walked intermittently according to a computer-generated random binary sequence on a treadmill for 20 minutes (with a constant speed of 1.7 mph and a slope of 10%). We used Fourier transform for beat-to-beat changes in ST level and the binary sequence of exercise. We then determined the transfer function by taking the ratio of Fourier transformed ST level to exercise over the frequency range of 0.5 through 5.0 cycles/min. Converting the transfer function to the time domain yielded the impulse response of ST change. The subjects consisted of 49 patients (60 +/- 9 years) with effort angina, 13 patients with atypical chest pain (56 +/- 9 years), and 30 healthy, male volunteers (23 +/- 7 years). In 82 subjects (89%), the ST impulse response showed an initial depression followed by a smooth, gradual restoration toward the preexercise ST level (type I response). The average duration of the initial depression was 8 +/- 3 seconds in the healthy volunteers, whereas it was significantly prolonged to 23 +/- 14 seconds in effort angina (p less than 0.05). The depression in patients with atypical chest pain was not significantly different from that in the healthy volunteers.(ABSTRACT TRUNCATED AT 250 WORDS)

A new method to identify dynamic transduction properties of aortic baroreceptors.

We identified, in 17 alpha-chloralose-anesthetized rabbits, the dynamic transduction characteristics of the aortic arch baroreceptors using a "white-noise technique." We recorded aortic pressure and aortic depressor nerve activity while perturbing pressure by rapid, intermittent ventricular pacing (400 beats/min). Dividing the cross-power spectrum between nerve activity and pressure by the power spectrum of pressure yielded the transfer function. The gain of the transfer function increased threefold as the frequency increased from 0.005 to 5 Hz, suggesting that the baroreceptors responded primarily to dynamic rather than to static changes in pressure. To quantify the nonlinear properties of baroreceptor transduction, we compared measured instantaneous nerve activity with that linearly predicted. We demonstrated that the major nonlinearity was attributable to "threshold". The overall baroreceptor transduction properties could be represented by a cascade connection of a linear subsystem followed by a nonlinear subsystem with threshold. The white-noise technique made it possible to identify the unbiased linear properties in a nonlinear system, and thus was very useful in identifying complex biological systems.

Autoregressive analysis of aortic input impedance: comparison with Fourier transform.

We evaluated the advantages of the autoregressive (AR) model over the conventional Fourier transform in estimating aortic input impedance. In 10 anesthetized open-chest dogs, we digitized aortic pressure and flow at 200 Hz for 51.20 s under random ventricular pacing and subdivided them into five segments. We obtained aortic input impedance over the frequency range of 0.1-20 Hz both by AR model and by Fourier transform for various lengths of data, i.e., from one to four consecutive segments. For any given data length, the impedance spectrum estimated by the AR model was smoother than that obtained by the Fourier transform. To evaluate the accuracy of the estimated impedance, we predicted instantaneous aortic pressure of the fifth segment by convolving corresponding aortic flow with the impulse response of aortic input impedance. The prediction error was less with the AR model than that resulting from Fourier transform as long as the number of the segments was less than four. We conclude that the AR model provides a more accurate estimate of aortic input impedance than does the Fourier transform when data length is limited.

[Malignant fibrous histiocytoma of the heart].

A 59-year-old woman was referred to our hospital by a local cardiologist, with unknown cause of congestive heart failure and respiratory failure. No significant heart murmur was heard and a cardioechogram from the anterior chest was insufficient for diagnosis. On the night of admission, cardio-respiratory shock was found, and Swan-Gantz catheter data showed severe pulmonary hypertension. Transesophageal echo-cardiography (TEE) revealed a left atrial tumor, with wide neck anchored onto the posterior wall of the left atrium, and which was floating into the left ventricle during the diastolic phase. An emergency operation was performed and the tumor, (80 by 50 by 48 mm) was resected. The patient recovered well in the postoperation period. However the residual tumor continued to grow gradually in the pericardial cavity and the patient died 3 months after the operation. Primary MFH of the heart is rare and 29 cases have been reported. The prognosis of MFH is poor despite surgery. Whenever a left atrial tumor with a wide neck is attached to the posterior wall, it must be considered to be possibly malignant and surgical resection is recommended.

No gender effect on binding characteristics of phenytoin to serum proteins in monotherapy for adult patients with epilepsy.

The aim of the present study was to determine the gender-related binding characteristics of phenytoin (PHT) to serum proteins in adult patients with epilepsy. Serum samples examined in the study were obtained from 80 adult patients (40 men and 40 women) with epilepsy on PHT monotherapy. Their age ranged from 16 to 64 years (mean [SD], 36.0 [11.7] years). Protein binding of PHT was evaluated by ultrafiltration under current laboratory routine conditions (25 +/- 3 degrees C). The in vivo binding parameters of PHT to serum proteins were determined using a binding equation derived from the Scatchard equation for a one-site binding model. No significant differences were observed in age and serum concentrations of albumin between male and female patients (p > 0.05), but significant differences were observed in serum concentrations of total and unbound PHT between the two groups (p < 0.05). The mean association constant of PHT to serum proteins is the same value of 0.008 L micromol(-1) between male and female patients, whereas total concentration of binding sites seems to be similar between the two groups (1389 micromol L(-1) for men and 1345 micromol L(-1) for women). No significant differences were observed in binding characteristics of PHT to serum proteins between male and female patients (p > 0.05). Our results show that gender does not have a significant effect on the binding characteristics of PHT to serum proteins in adult patients receiving monotherapy under normal pathophysiologic conditions.