Kainic acid inhibits cholecystokinin release from rat hippocampal slices

Antagonistic interactions between cholecystokinin (CCK) and nanomolar concentrations of kainic acid (KA) have been reported in area CA3 of the rat hippocampal slice. This study tested the possibility that kainic acid inhibits the release of CCK. Elevated K+ was found to release CCK from hippocampal slices in a Ca2+-dependent manner. KA, at concentrations as low as 100 nM, inhibited this release by about one-third. Because CCK appears to exert a net inhibitory effect on the firing of CA3 pyramidal cells, the epileptogenic action of KA may be explained, in part, by the depression of CCK release.

Glucocorticoids potentiate kainic acid-induced seizures and wet dog shakes

Glucocorticoid effects on kainic acid-induced motor seizures and wet dog shakes in rats were investigated by adrenalectomy and dexamethasone treatment. One-day adrenalectomy attenuated kainic acid-induced wet dog shakes and seizure activity. These effects were restored by dexamethasone. Administration of dexamethasone to non-adrenalectomized rats potentiated kainic acid-induced wet dog shakes and severity of seizure activity. These results suggest that glucocorticoids may play an important role in modulating the severity of kainic acid-induced seizures and wet dog shakes.

Opioids induce convulsions and wet dog shakes in rats: mediation by hippocampal mu, but not delta or kappa opioid receptors

The opioid receptor subtypes and brain regions involved in eliciting convulsions and wet dog shakes (WDS) were studied by testing different opioid receptor selective agonists in unanesthetized rats. Selective mu agonists, [NMe-Phe3-D-Pro4]-morphiceptin (PL017) and [D-Ala2-N-methyl-Phe3-Gly5-ol]-enkephalin, induced convulsions and WDS when unilaterally injected into the ventral hippocampus. [D-Ala2,D-Leu5]-enkephalin (DADLE), a mixed mu and delta agonist, also elicited such behavioral changes, but its effect was less potent than the selective mu agonists. DADLE-induced WDS were dose dependent, and both convulsions and WDS were antagonized by the irreversible mu receptor antagonist, beta-funaltrexamine, but not by the selective delta receptor antagonist, ICI-174,864. Treatment with the selective delta agonist [D-Pen2,5]-enkephalin or the selective kappa agonists U-50,488H, dynorphin-A amide, or dynorphin-A(1-8) did not produce convulsions or WDS. The injection of a high dose of PL017 intraventricularly or into other brain regions such as the dorsal hippocampus, frontal cortex, striatum, and amygdala did not produce convulsions or WDS, therefore suggesting the ventral hippocampus is an important site for the expression of opioid-induced convulsions and WDS. These results suggest that opioid-induced convulsions and WDS are mediated exclusively by mu but not delta or kappa opioid receptors in the ventral hippocampus.

Percutaneous cholecystolithotomy

We have successfully removed gallstones percutaneously from the gallbladders in two poor surgical risk patients using the standard equipment and the principles of percutaneous nephrolithotomy. No complication occurred in either patient. A brief review of percutaneous gallstone extraction is presented.

High-irradiance 248-nm laser system

A laser system that routinely generates irradiances of 8 x 10(17) W cm(-2) is described. Pulses from a mode-locked visible dye laser are heterodyned to 248 nm and amplified in two KrF amplifiers. Output is 25-30 mJ in a 700-fsec pulse that can be focused to 5 microm(2).

Silicone polymer uptake method for determination of cholesterol thermodynamic activity in model bile systems

Cholesterol in bile has been linked to the incidence of gallstone disease through the concept of supersaturation as measured by the cholesterol saturation index (CSI). The latter is a linear function of cholesterol concentration and is based on the assumption that all cholesterol in bile is solubilized and transported in bile salt-lecithin (BS-L) mixed micelles, as well as in bile salt simple micelles. In light of the discovery of the cholesterol-lecithin vesicles as significant cholesterol carriers, there is a need to re-evaluate this old concept. This study examined the feasibility of the silicone polymer uptake method for the direct determination of the cholesterol thermodynamic activity (AT) in model bile systems. In cases of unsaturation and near saturation, a linear relationship was observed between CSP,Eq, the cholesterol concentration in the silicone polymer at equilibrium, and CAq,Eq/Cs,Aq for taurocholate (TC), taurochenodeoxycholate (TCDC), and tauroursodeoxycholate (TUDC) systems either containing or not containing lecithin. Here, CAq,Eq is the cholesterol concentration in the aqueous micellar solution at equilibrium, and Cs,Aq is the cholesterol monohydrate solubility of the same medium. In TC-L solutions supersaturated with cholesterol, the linear relationship continued to hold up to the point where vesicles started to form. Vesicle formation initiated a negative deviation from linearity. At constant lecithin concentration, the CSP,Eq value, or the cholesterol thermodynamic activity at which vesicle formation began, was a function of the TC:L ratio; the larger the TC:L ratio, the higher the cholesterol thermodynamic activity for the onset of vesicle formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of tyrosine hydroxylase and phenylethanolamine N-methyltransferase mRNA levels in the sympathoadrenal system by the pituitary-adrenocortical axis

The pituitary-adrenocortical axis plays a complex role in the regulation of the levels of enzymes of the catecholamine biosynthetic pathway. In this report we have explored molecular mechanisms of these regulations, by examining the effects of hypophysectomy (HPX) and dexamethasone (DEX) on tyrosine hydroxylase (TH) and phenylethanolamine N-methyltransferase (PNMT) mRNA levels in the adrenal medulla (AM) and superior cervical ganglia (SCG). Three weeks after hypophysectomy weights (-48%), total RNA (-49%), and DNA (-22%) contents in AM were significantly reduced, when compared to sham-operated animals (SO). In SCG decreases in weight (-23%) and in the ratio of RNA/DNA (-25%) were also found. TH mRNA contents paralleled decreases in total RNA levels and no significant change in the relative abundance of TH mRNA was found. When HPX rats were injected for 5 days with DEX (1 mg/kg, i.p.), TH mRNA levels in the SCG (+51%) and in the AM (+74%) were significantly increased when compared to saline-treated HPX animals. DEX given to SO rats increased TH mRNA in SCG (+49%); a 27% increase in TH mRNA in the AM was also observed. The relative abundance of PNMT mRNA in the AM was reduced after hypophysectomy (-64%). This decrease was completely reversed by DEX. In contrast, DEX did not affect PNMT mRNA levels in the AM of SO rats. PNMT mRNA was not detected in SCG of saline- or DEX-treated rats. In conclusion, our findings suggest that the pituitary-adrenocortical axis is involved in the regulation of the steady-state levels of TH and PNMT mRNAs. This regulation involves: (1) induction of TH mRNA contents in AM and SCG by increased plasma glucocorticoid levels; and (2) maintenance of the steady-state levels of PNMT mRNA in AM by glucocorticoid-dependent mechanisms.

Roles of the pituitary-adrenocortical axis in control of the native and cryptic enkephalin levels and proenkephalin mRNA in the sympathoadrenal system of the rat

The effects of hypophysectomy (HPX) and dexamethasone (DEX) on the levels of Met5-enkephalin (ME), ME precursors, and the abundance of proenkephalin (pEK) mRNA, were examined in the adrenal medulla (AM) and superior cervical ganglia (SCG). To assess possible changes in enkephalin processing, both cryptic (after trypsin and carboxypeptidase B digestions) and native (without enzyme digestions) ME-like immunoreactivity (ME-LI) was measured. Three weeks after HPX the proportion of pEK mRNA to the total RNA content in the AM was not significantly changed when compared to sham-operated (SO) animals. Total (native + cryptic) ME-LI was decreased by 45% in the AM of HPX rats. This decrease was paralleled by a 58% depletion of AM proteins. Cryptic ME-LI was also reduced by 43%. In contrast, native ME-LI was not altered after HPX, indicating enhanced processing of ME precursors. Treatment with DEX (5 daily injections--1 mg/kg, i.p.) increased the relative abundance of pEK mRNA (+27%) and total ME-LI in the AM of HPX group, but not in SO group. Native ME-LI, cryptic ME-LI, and their ratio were not significantly affected by DEX in the AM of HPX or SO rats. In SCG, the relative abundance of pEK mRNA decreased by 25% after hypophysectomy. Total and cryptic ME-LI in the SCG of HPX rats were not changed when compared to SO rats. In contrast, HPX reduced native ME-LI suggesting decreased processing of ME precursors. Similarly, as in AM, DEX produced increase in the SCG pEK mRNA only in HPX (+68%) and not in the SO rats. In SCG, DEX produced decreases in total ME-LI which could be attributed to an increased enkephalin release. An overall reduction of cryptic ME-LI was also observed after DEX, whereas native ME-LI remained unchanged suggesting increased processing of enkephalins. Our findings indicate that the pituitary adrenocortical axis controls the relative proportions of ME to its precursors, and that this control involves both glucocorticoid-dependent (SCG) and glucocorticoid-independent (AM) mechanisms. In contrast, our studies do not suggest specific control of pEK synthesis by the pituitary adrenocortical axis. The pituitary adrenocortical axis may also influence the relative contents of ME and catecholamines in the AM and SCG. The ratio of ME/catecholamines increased after HPX (AM and SCG) and after DEX (SCG). Such regulation may contribute to the control of co-transmitter output in the sympathoadrenal system.

Intrahippocampal injections of a specific mu-receptor ligand PL017 produce generalized convulsions in rats

The effects of a selective mu-agonist, [NMe-Phe3-D-Pro4]morphiceptin (PL017), and a selective mu-antagonist, beta-funaltrexamine (beta-FNA), on convulsions and wet dog shakes (WDS) were studied. Electroencephalogram demonstrated that a single injection of PL017 into the ventral hippocampus evoked epileptiform spiking which appeared initially in the ventral hippocampus and spread to the cortical area when the animal developed generalized convulsion. Behavioral studies showed that PL017-induced convulsions and WDS were dose-dependent, and these behavioral changes were blocked by beta-FNA pretreatment. The results indicate that mu-receptors in the hippocampus may play an important role in seizure activities evoked by opioids.

Effects of corticosterone on shaking and seizure behavior induced by deep prepyriform cortex kindling

The influence of adrenocorticosteroids on seizures and wet dog shakes (WDS) induced by deep prepyriform cortex kindling was studied by bilateral adrenalectomy and corticosterone replacement. The rate of kindling, latency to the onset and duration of motor seizures were not significantly affected by adrenalectomy or corticosterone treatment. However, the number of WDS observed after stage 5 seizures was reduced in adrenalectomized animals and it was not restored until 3 h following corticosterone replacement. This delay in onset of action suggests that the effects of adrenocorticosteroids and/or ACTH on WDS may be mediated by an indirect mechanism.

A clinically "silent" pheochromocytoma with spontaneous hemorrhage

We report a case of an abdominal mass that had hemorrhaged spontaneously into the retroperitoneal space and presented as an acute abdominal catastrophe. The pathological diagnosis was pheochromocytoma, although the patient had no suggestive symptoms preoperatively. The management of this silent pheochromocytoma and its atypical presentation are discussed.

Heterotopic heart transplantation in the rat receiving FK-506 alone or with cyclosporine

In rats, FK significantly prolonged heterotopic heart graft survival over a wide dose range when given for 2 weeks starting on the day of the operation. Brief courses of FK for one to four days preoperatively, and especially beginning four days postoperatively, allowed long subsequent survival of heart grafts in otherwise untreated recipients. The seeming acceptance of the grafts with postoperative FK treatment was largely but not exclusively donor specific when tested eight days after the last FK dose by second grafts from the same donor v third-party donor grafts. FK in minimally therapeutic doses was synergistic with suboptimal doses of CyA.

Characterization of the binding of a morphine (mu) receptor-specific ligand: Tyr-Pro-NMePhe-D-Pro-NH2, [3H]-PL17

The highly mu-receptor-selective ligand Tyr-Pro-NMePhe-D-Pro-NH2 (PL17) was custom tritiated and its binding to rat brain membranes was directly measured. The data were well fit by a model assuming the existence of a single homogeneous population of binding sites. Scatchard analysis yielded values for Kd and binding sites of 6 nM and 0.16 pmol/mg, respectively. As expected for binding to an opiate receptor, addition of sodium, magnesium, and guanyl nucleotides to the assays resulted in a modulation of ligand binding. In all cases tested, however, no significant deviations of the Scatchard plots from linearity were observed. Furthermore, displacement of [3H]-PL17 by all opioid ligands tested was monophasic, consistent with simple competitive inhibition at a single binding site. The IC50 values thus obtained showed good agreement with previously published values determined using less selective radiolabeled ligands. The regional distribution of [3H]-PL17 binding to rat brain was examined by in vitro autoradiography. The labeling pattern was similar to that seen for other mu-type ligands. Because of its high selectivity, the binding of [3H]-PL17 to the mu-type receptor can be measured directly without the need to suppress binding to other sites. As such, [3H]-PL17 should be a useful ligand for dissecting the actions of multiple opiate receptors.

Changes induced by corticosterone and adrenalectomy in synaptosomal and platelet uptake and binding of 5-HT. The relationship to [3H]imipramine binding

A comparative study of the effect of adrenalectomy, treatment with corticosterone, and imipramine on platelet an synaptosomal uptake was undertaken. One day after adrenalectomy, uptake of 5-hydroxytryptamine (5-HT) in the platelet and the hypothalamus was significantly decreased with an increase in the apparent Km, but the uptake of 5-HT of the cerebral synaptosomes was unchanged. In this group, the Kd of low affinity binding of 5-HT was also increased in the hypothalamic synaptosomes and in the platelet preparations. Treatment with corticosterone (5 mg/kg, i.m.) restored the decrease in the uptake of 5-HT induced by adrenalectomy in the hypothalamic synaptosomes and in the platelets, and significantly increased the uptake of 5-HT of these fractions in sham-operated rats. The binding of 5-HT was unchanged by acute treatment with corticosterone. The effectiveness of imipramine varied with the preparation and treatment group. The IC50 of the cerebral synaptosomal preparation was greater than that of the hypothalamic synaptosomal preparation. Using this latter preparation, the IC50 for imipramine in adrenalectomised, sham-operated and corticosterone-treated rats were found to be 0.04, 0.09 and 0.25 microM, respectively. These changes in sensitivity to imipramine were not reflected in the binding of [3H]imipramine which was unchanged.

Examination of the Sephadex G10 beads uptake method for determination of bile salt monomer concentration in taurocholate-lecithin solutions

Experiments have been undertaken to examine the validity of the method of Ammon and Walter for the determination of bile acid monomer concentrations in taurocholate-lecithin (TC-L) solutions. The procedure involves, basically, the uptake of the bile acid monomer by Sephadex G10 beads (exclusion limits 700 Da) in the presence of a suitable aqueous phase marker (raffinose). Several of the experimental variables involved in the bead-washing technique have been critically studied, and good precision in data (SD in the range of +/- 2-5% of the mean value) has been obtained. Monomer concentrations determined in the absence of lecithin over a wide range (10-70 mM) of TC were found to be in agreement with those obtained by Ammon. Most important, however, is the finding that TC monomer concentrations at constant NMBS were found to be constant in all solutions containing or not containing lecithin [here, the nonmixed micelle bile salt (NMBS) is the total bile salt concentration, but not including species involving lecithin, and is determined by dialysis equilibrium experiments].

The menstrual cycle and platelet 5-HT uptake

The association between the onset of depressive illness and the paramenstruum has been reported. In the present study, we looked at changes in platelet 5-HT uptake in six healthy, regularly menstruating subjects on days 1, 10, and 24 of three consecutive menstrual cycles to explore possible biochemical bases for mood changes associated with menstruation. Platelet 5-hydroxytryptamine (5-HT) uptake was determined by suspension of platelet pellets in 0.5-5 microM hydroxy [G-3H] tryptamine [( 3H]-5-HT) creatinine sulfate solution at 37 degrees C and measurement of radioactivity of [3H]-5-HT in the platelets using liquid scintillation counting. Mood changes were measured using the Moos Menstruation Distress Questionnaire and the Spielberger State Anxiety Scale. Analysis of variance and trend analysis revealed significant elevation of Km and Vmax on day 24 of the cycle, which was consistent across the three menstrual cycles studied. A significant linear rise of "negative affect" across each cycle peaking on day 1 was detected. "Water retention" and "behavioral change" also peaked on day 1. No significant correlation, however, was obtained between the mood scores and platelet 5-HT uptake. These findings are discussed.

Serotonin uptake and imipramine binding in rat platelets after chronic dexamethasone and amitriptyline treatment

Chronic adrenocorticotrophin treatment was shown to decrease platelet 5HT uptake, increase Km and decrease Vmax. Similarly, chronic dexamethasone treatment decreased 5HT uptake, but had no effect on the Kd and Bmax of high affinity imipramine binding sites in the platelets. Chronic amitriptyline treatment induced similar changes, with the exception that the drug induced a decrease in the number of high affinity imipramine binding sites. Chronic dexamethasone treatment potentiated the effects of amitriptyline and decreased the IC50 of imipramine and desipramine as 5HT uptake inhibitors in vitro. The results suggest that whereas 5HT uptake is related to high affinity imipramine binding sites, it can be modified independently of the high affinity imipramine binding.

Further studies on the effects of adrenal steroids in the active transport of serotonin into rat platelets

Male rats were treated with a fixed dose of aminoglutethimide (50 mg/kg s.c.) or with progressively increasing doses (50-100 mg/kg s.c.) for 3 days. Corticosterone levels were found to be decreased in the latter group. Platelet uptake of serotonin as well as the apparent Vmax were decreased, whereas the Km of uptake were increased when compared with that of the control group. Addition of ACTH (10 iu/dl) to control rat platelet and corticosterone (10-80 micrograms/dl) or triamcinolone (0.5-5.0 micrograms/dl) to adrenalectomized rat platelet suspension in vitro did not increase the serotonin uptake of the preparation. Administration of exogenous dexamethasone (0.05-0.2 mg/kg i.m.) or triamcinolone (0.05-5.0 mg/kg i.m.) to adrenalectomized rats, caused a dose related increase in active uptake of serotonin by the platelets. Deoxycorticosterone (0.1-1.0 mg/kg i.m.) did not have this effect. The time course of response to, and the maximum percentage increase in platelet serotonin uptake by, exogenous corticosteroids are related to their glucocorticoid potency. The possible role of glucocorticoids on platelet serotonin uptake process is discussed.

Effect of steroids on the inhibition of platelet 5HT uptake by desipramine and other antidepressants

The inhibitory effect of desipramine on platelet 5HT uptake was tested ex vivo and in vitro in control, adrenalectomised and triamcinolone-treated rats. In both situations, the inhibitory effect of desipramine was augmented in adrenalectomised rats and decreased in triamcinolone-treated rats. These changes in desipramine sensitivity were accompanied by changes in the uptake kinetic components, Km and Vmax. In in vitro studies, the IC50 of clomipramine, fluvoxamine, zimelidine, imipramine and nomifensine was decreased in adrenalectomised rat platelets and increased in corticosterone-, dexamethasone- or triamcinolone-treated rat platelets. Deoxycorticosterone had no effect. Testosterone only affected the IC50 of desipramine and nomifensine.

Preliminary study of neutrophil leukocyte function in uremic patients and renal transplant recipients

Rejection and infection are two major problems that affect the success of renal transplantation. Renal transplant recipients should be on immunosuppressants after surgery and this in turn gives rise to the susceptibility of the recipients to infection. In this study, we have monitored: Neutrophil leukocyte chemotaxis; Neutrophil leukocyte subpopulation; Lymphocytes, T-cells, B-cells, active T-cells population among uremic patients, renal transplant recipients, control subjects of hospital staff and renal graft donors. The results indicate that there is no discernible difference between uremic patients, renal transplant recipients and control subjects in neutrophil leukocyte chemotaxis. However, the neutrophil leukocyte subpopulation of the transplant recipients is significantly low. The T-lymphocyte population of the transplant recipients was also decreased. This phenomenon is often found shortly after transplantation. The higher incidence of early post-transplant infection might probably be attributed to the decrease of neutrophil leukocyte subpopulation and total T-lymphocyte population in the recipients undergoing massive immunosuppression. When the situation of the transplant recipients becomes stable and when they are given minimal maintenance dose of immunosuppressive drugs, their T-lymphocyte population becomes normal both in morphological count and functional assay.

Effects of adrenalectomy and adrenal steroids on the uptake of serotonin in rat platelets

Changes induced by adrenalectomy, triamcinolone treatment and deoxycorticosterone (DOC) treatment on the uptake of [3H]-serotonin into platelets were studied ex vivo, using rat platelets suspended in physiological medium. Adrenalectomy caused a decrease in active uptake of serotonin and an associated increase in apparent Km. Treatment of the adrenalectomized rats with triamcinolone (0.25 mg/kg), but not DOC (1.0 mg/kg) restored the active uptake of serotonin. At triamcinolone dose of 0.5 mg/kg, the serotonin uptake was raised to a level that was significantly higher than normal. Kinetic analysis of uptake data showed the apparent Km to be affected by both triamcinolone and DOC, while the apparent Vmax of uptake rate was increased by triamcinolone treatment.

Monitoring of T lymphocytes before and after surgical removal of hepatic tumors

Monitoring of peripheral T lymphocyte level after surgical removal of hepatic tumors has been periodically carried out in thirty patients to observe the relation between T lymphocytes suppression and presence of tumor. Rosette formation with neuraminidase treated sheep erythrocytes has been considered as T lymphocytes. Twenty-two cases were considered as free from residual hepatic tumor after operation and eight cases were diagnosed as residual or recurrent hepatic tumor postoperatively. The result indicated that significant difference in T lymphocyte level has been observed between preoperative level (59.3 +/- 14.0%) and postoperative 4th week level (69.4 +/- 5.5%) 5th week level (69.5 +/- 8.3%) (both p less than 0.01) in group of complete removal of hepatic tumor. While in group of residual or recurrent hepatic tumor, the average T lymphocytes stayed at rather low level throughout the postoperative course. From another point of view, when we compare the T lymphocyte level between the two groups, significant difference has been observed either at postoperative 4th week (69.4 +/- 5.5% vs 57.8 +/- 12.7%) or at postoperative 5th week (69.5 +/- 8.3% vs 53.8 +/- 11.6%) (both p less than 0.01). Accordingly we believed that there is a close relation between depressed T lymphocyte level and presence of hepatic tumor.