Individual locomotor response to novelty predicts selective alterations in D1 and D2 receptors and mRNAs.

Rats that have a greater locomotor response to novelty (high responders, HR) have differences in measures of presynaptic dopamine transmission compared to low responders (LR) to a novel environment, including altered dopamine release and behavioral response to indirect dopamine agonists. This study examined the role of three dopamine terminal fields, the nucleus accumbens, striatum, and medial prefrontal cortex, in differences between HR and LR. In the first experiment, dopamine was infused directly into the nucleus accumbens (0, 3, 10, and 30 micrograms/side) or the striatum (0, 10, 30, and 100 micrograms/side).

The striatal transporter for dopamine in the rat may be kinetically up-regulated following 3 weeks of withdrawal from cocaine self-administration.

Rotating disk electrode voltammetry was used to measure the inwardly directed Vmax and Km of dopamine with its transporter in striatal suspensions prepared from nonhandled control rats, rats that had been trained to self-administer cocaine for 20 days (at 26 mg/day per rat) via a jugular catheter and subsequently withdrawn for 3 weeks, and rats that had received saline (155 mM NaCl) via a jugular catheter on the same schedule as the rats that had received cocaine. Because a limited number of animals was available from the self-administration procedure, the velocity of dopamine transport as a function of [dopamine] was measured by incremental addition of dopamine to a given striatal preparation. In nonhandled controls the values of Vmax, Km, and turnover, observed in this experimental paradigm, were increased relative to results obtained in studies of the velocity-[dopamine] relationship where dopamine was added to suspensions, one concentration per suspension.

Effects of cocaine and repeated cocaine followed by withdrawal. Alterations of dopaminergic transporter turnover with no changes in kinetics of substrate recognition.

The turnover of the transporter for dopamine (ca. 1.5 sec-1) and the apparent second order rate constant of association of dopamine with the outward facing form of the transporter protein (ca.

Integrated cardiovascular function in the conscious streptozotocin-diabetic deoxycorticosterone-acetate-hypertensive rats.

Blood pressure, heart rate, and left ventricular function were measured in conscious diabetic Sprague-Dawley rats subjected to 5 weeks of deoxycorticosterone acetate (DOCA) treatment which was started 1 week following intravenous injection of streptozotocin (STZ) (60 mg/kg) to induce diabetes mellitus. It was found that chronic administration of DOCA in nondiabetic animals caused an increase in blood pressure and functional parameters of left ventricle, and a decrease in heart rate and plasma insulin levels. Normotensive diabetic rats exhibited hyperglycemia, hypoinsulinemia, and a lower body weight as compared with control animals but did not show significant abnormalities in cardiovascular function.

Striatal transporter for dopamine: catechol structure-activity studies and susceptibility to chemical modification.

The apparent second-order association rate constant of dopamine binding to the striatal transporter (approximately 1 x 10(6) M-1 s-1) as well as the transporter turnover number (approximately 1.5 s-1) was estimated using rotating disk electrode voltammetry to monitor apparent zero trans entry of dopamine into striatal suspensions. The substrate specificity of the transporter was also assessed using catechol derivatives.

Emergent conditional discrimination in children: matching to compound stimuli.

This study reports two experiments that first taught preschool children identity-matching to compound sample and compound comparison stimuli. A compound stimulus consisted of a colour and a form superimposed on one another. Test sessions assessed whether children related the form and colour elements of a particular compound stimulus.

D2 receptors may modulate the function of the striatal transporter for dopamine: kinetic evidence from studies in vitro and in vivo.

Recently it was hypothesized by others that the D2 dopamine receptor can regulate the uptake of dopamine. However, the evidence in support of this hypothesis, although compelling, was not based on observations related to direct measures of the kinetic activity of the transporter itself. Here kinetic evidence in support of this hypothesis is shown.

Blockade of dopamine autoreceptors by haloperidol and the apparent dynamics of potassium-stimulated endogenous release of dopamine from and reuptake into striatal suspensions in the rat.

A study was made to determine what effects the blockade of dopamine (DA) autoreceptors has on the dynamics of depolarization-stimulated release of DA from suspensions of the striatum. A rotating disk electrode voltammetric technique and a first order kinetic model were used to measure and quantify time-resolved depolarization-induced release of DA from and reuptake into the same striatal suspension. Multiphasic dose-response relationships between the magnitudes, rates and apparent rate constants of release of DA and the concentration of the autoreceptor antagonist, haloperidol, were observed.

A multisubstrate mechanism of striatal dopamine uptake and its inhibition by cocaine.

A study of Na+ and Cl- as co-substrates in dopamine uptake into striatal suspensions and inhibition of dopamine uptake by cocaine was made by monitoring the initial velocity of the uptake of exogenously added non-radioactively labeled dopamine using a rotating disk electroanalytical technique with 50 msec resolution. Dopamine, in the concentration range of 0.025 to 4.

Measurement of cardiac left ventricular pressure in conscious rats using a fluid-filled catheter.

A fluid-filled catheter consisting of 100 cm of PE50 polyethylene tubing welded to 7 cm of PE10 polyethylene tubing (PE50/PE10) was constructed for the purpose of measuring the rate of left ventricular pressure development (+dP/dt) in conscious, freely moving rats. Prior to in vivo experiments, four PE50/PE10 catheters were randomly selected, and their natural frequencies and damping ratios were determined using a square wave impact. The mean (n = 4), natural frequency of these catheters was shown to be 35.

The pathogenesis of DOCA-salt hypertension.

Deoxycorticosterone acetate (DOCA) is an agent commonly used to induce hypertension in experimental animals. This form of hypertension is dependent on altered regulation of central pressor mechanisms including the brain renin-angiotensin system. Additionally, there are characteristic changes involving the cardiovascular system and baroreflex responses.

A study of acrylic resin denture base material distortion using computer-aided holographic interferometry.

A holographic interferometer for investigating deformations of dental prostheses is described. Residual stress relaxation resulting from the polymerization of acrylic resin dentures is qualitatively studied during the first 48 hours following fabrication. The resulting fringe patterns show a symmetry that is correlated to the shape of the denture.

Interactions between the argininyl moieties of neurotensin and the catechol protons of dopamine.

The interaction between dopamine and neurotensin as well as other Arg-containing peptides was studied to provide more chemical details of how dopamine binds to the neuropeptide neurotensin. The stoichiometry of 1:1, dopamine to neurotensin, was confirmed by additional electroanalytical and ultraviolet-visible spectroscopic studies. By analyses of the 205- to 340-nm difference spectra of fixed concentrations of dopamine in the presence of increasing amounts of neurotensin, the dissociation constant of the interaction was found to be 5.

Effects of acute and chronic systemic administration of some typical antipsychotic drugs on turnover of dopamine and potassium ion-induced release of dopamine in the striatum of the rat in vivo.

Chronoamperometry was used to measure the dose dependency of antipsychotic drug (spiperone, haloperidol and chlorpromazine)-induced increases in depolarization-stimulated release of dopamine in the striatum of the rat in vivo. The dose-response curves were found to be at least biphasic (small doses increased release and large doses inhibited release) and different in shape from dose-response curves for increases in the turnover of dopamine, suggesting that the two processes may not be related. The threshold dose to induce increased depolarization-stimulated release of dopamine correlated with the values in the literature for doses required to block stereotype induced by apomorphine and amphetamine and doses sufficient to cause a maximal increase in release correlated with the doses required for the induction of catalepsy.

Neurotensin binding to dopamine.

Rotating disk electrode voltammetry at glassy carbon electrodes and ultraviolet/visible spectroscopy were used to demonstrate that dopamine binds to neurotensin with a dissociation constant of 7.5 x 10(-8). By measuring the binding constants of various neurotensin analogs, it was found that the -Arg8-Arg9-portion of the neurotensin sequence is critical for binding dopamine.

Application of the chromogenic reaction to conventional silver staining, the Ag-NOR staining and the silver-intensified immunogold technique.

The principle of the chromogenic reaction and the transformation of "black and white" histochemical staining results or immunohistochemical signals to coloured microscopic images is described. The chromogenic reaction was optimized and is, so far, possible with either cyan-blue or magenta-red reaction products. The application of the chromogenic reaction to conventional silver stain was optimal in the Lendrum staining resulting in red or blue stained reticulin fibres.

The safety and usefulness of buspirone as an anxiolytic drug in elderly versus young patients.

Buspirone, the prototype of the new azaspirodecanedione series of antianxiety drugs, was studied in over 6,000 patients in an open, multicenter trial to confirm its safety and usefulness for anxiety in a typical medical practice setting. Non-psychotic patients with clinically manifest anxiety that required anxiolytic drug therapy were enrolled to receive four weeks of treatment with a fixed dose of buspirone (15 mg/day). Patient data were analyzed according to age: the elderly group comprised 605 patients aged 65 years or older, and the younger group included 5,969 patients less than 65 years old.

Effects of extender and insemination dose on postthaw quality and fertility of bovine sperm.

Quality and fertility of sperm extended in egg yolk-Tes-Tris were compared with those of sperm in egg yolk-citrate and homogenized milk extenders. Extended semen was frozen in .5-ml plastic straws at 11, 15, 17, or 22 X 10(6) sperm per insemination dose.

Effects of exposing bovine sperm to bovine serum albumin, or freeze-thawing, on sperm-bound amidase activity.

Isolation of a self-selected population of motile spermatozoa is possible by using a gradient of bovine serum albumin (BSA). We determined if exposure to BSA altered the sperm or if isolated sperm differed from nonisolated cells in terms of motility or activity of sperm-bound amidase, either before or after subsequent cryopreservation. Exposure of sperm to 6% BSA in egg yolk Tris extender induced changes in the plasma and acrosomal membranes of sperm that resulted in exposure and activation of sperm-bound amidase (P less than .

Temporal relationship between neurotransmitter release and ion flux during spreading depression and anoxia.

Brain ion homeostasis is severely perturbed during spreading depression of Leao and during anoxia. The ionic composition of the extracellular space changes abruptly and approaches the intracellular concentrations owing to an increase in cell permeability. In spreading depression, synchronous transmitter efflux caused by a depolarization of the presynaptic terminals has been implicated as a possible mechanism that would explain the concomitant movement of ions.

Sperm-bound amidase activity as a marker for acrosomal integrity in bull spermatozoa.

An assay for sperm-bound amidase activity was validated using bovine spermatozoa and N-benzoyl-DL-arginine p-nitroanilide as substrate. The assay had intra- and interassay coefficients of variations of 5 and 12%, respectively. It is an inexpensive, simple and rapid assay since 100 samples can be evaluated in 2 hours and it requires only 4 X 10(6) spermatozoa per sample.

Extraversion, neuroticism, and sexual behavior: interrelationships in a sample of young men.

In his theory on sexuality and personality Eysenck proposed a positive correlation between extraversion and intensified sexual behavior and between neuroticism and problems in sexual behavior. An earlier study with married persons did not show any of these correlations. It was hypothesized that this connection exists only for unmarried persons who are not engaged in long-lasting relationships, because in the latter the quality of the relationship determines the sexual interaction.