Liquid chromatographic analysis of catecholamines routine assay for regional brain mapping

Large nesting expression in deer mice remains stable under conditions of visual deprivation despite heightened limbic involvement: Perspectives on compulsive-like behavior

Visual stimuli and limbic activation varyingly influence obsessive-compulsive symptom expression and so impact treatment outcomes. Some symptom phenotypes, for example, covert repugnant thoughts, are likely less sensitive to sensory stimuli compared to symptoms with an extrinsic focus, that is, symptoms related to contamination, safety, and "just-right-perceptions." Toward an improved understanding of the neurocognitive underpinnings of obsessive-compulsive psychobiology, work in naturalistic animal model systems is useful. Here, we explored the impact of visual feedback and limbic processes on 24 normal (NNB) and large (LNB) nesting deer mice, respectively (as far as possible, equally distributed between sexes). Briefly, after behavioral classification into either the NNB or LNB cohorts, mice of each cohort were separated into two groups each and assessed for nesting expression under either standard light conditions or conditions of complete visual deprivation (VD). Nesting outcomes were assessed in terms of size and neatness. After nesting assessment completion, mice were euthanized, and samples of frontal-cortical and hippocampal tissues were collected to determine serotonin and noradrenaline concentrations. Our results show that LNB, as opposed to NNB, represents an inflexible and excessive behavioral phenotype that is not dependent on visually guided action-outcome processing, and that it associates with increased frontal-cortical and hippocampal noradrenaline concentrations, irrespective of lighting condition. Collectively, the current results are informing of the neurocognitive underpinnings of nesting behavior. It also provides a valuable foundation for continued investigations into the noradrenergic mechanisms that may influence the development and promulgation of excessive, rigid, and inflexible behaviors.

Ndufs4 KO mice: A model to study comorbid mood disorders associated with mitochondrial dysfunction

The Ndufs4 knockout (KO) mouse is a validated and robust preclinical model of mitochondrial diseases (specifically Leigh syndrome), that displays a narrow window of relative phenotypical normality, despite its inherent mitochondrial complex I dysfunction and severe phenotype. Preclinical observations related to psychiatric comorbidities that arise in patients with mitochondrial diseases and indeed in Leigh syndrome are, however, yet to be investigated in this model. Strengthening this narrative is the fact that major depression and bipolar disorder are known to present with deficits in mitochondrial function. We therefore screened the behavioural profile of male and female Ndufs4 KO mice (relative to heterozygous; HET and wildtype; WT mice) between postnatal days 28 and 35 for locomotor, depressive- and anxiety-like alterations and linked it with selected brain biomarkers, viz. serotonin, kynurenine, and redox status in brain areas relevant to psychiatric pathologies (i.e., prefrontal cortex, hippocampus, and striatum). The Ndufs4 KO mice initially displayed depressive-like behaviour in the tail suspension test on PND31 but not on PND35 in the forced swim test. In the mirror box test, increased risk resilience was observed. Serotonin levels of KO mice, compared to HET controls, were increased on PND36, together with increased tryptophan to serotonin and kynurenine turnover. Kynurenine to kynurenic acid turnover was however decreased, while reduced versus oxidized glutathione ratio (GSH/GSSG) was increased. When considering the comorbid psychiatric traits of patients with mitochondrial disorders, this work elaborates on the neuropsychiatric profile of the Ndufs KO mouse. Secondly, despite locomotor differences, Ndufs4 KO mice present with a behavioural profile not unlike rodent models of bipolar disorder, namely variable mood states and risk-taking behaviour. The model may elucidate the bio-energetic mechanisms underlying mood disorders, especially in the presence of mitochondrial disease. Studies are however required to further validate the model's translational relevance.

Determination of Catecholamines in a Small Volume (25 μL) of Plasma from Conscious Mouse Tail Vein

The determination of plasma catecholamine levels is commonly used as a measure of the sympathetic nervous system's response to stress and is highly important for diagnosis, therapy, and prognosis of cardiovascular diseases, catecholamine-secreting tumors arising from the chromaffin cells of the sympathoadrenal system, and affective disorders. Diseases in which catecholamines are significantly elevated include pheochromocytoma, Parkinson's disease, Alzheimer's disease, neuroblastoma, ganglioneuroblastoma, von Hippel-Lindau disease, baroreflex failure, chemodectina (nonchromaffin paraganglioma), and multiple endocrine neoplasia. Plasma norepinephrine levels provide a guide to prognosis in patients with stable, chronic, and congestive heart diseases. The method described here for the determination of plasma catecholamines is based on the principle that plasma catecholamines are selectively adsorbed on acid-washed alumina at pH 8.7 and then eluted at a pH between 1.0 and 2.0. Upon injection, catecholamines in elutes were separated by a reversed phase C-18 column. After separation, the catecholamines present within the mobile phase enter the electrochemical detector. Electrochemical detection occurs because electroactive compounds oxidize at a certain potential and thereby liberate electrons that create measurable current. Catecholamines readily form quinones under these conditions, get oxidized, release two electrons, and create current. The electrochemical detector detects this electrical current that linearly correlates to the catecholamine concentration loaded into the ultra-performance liquid chromatography instrument. A 15-min mixing time during the adsorption and desorption steps was found to be optimal. If the washing step was omitted, the catecholamines could not be eluted from the acid-washed alumina. To prevent dilution, the alumina had to be centrifuged and not aspirated to dryness after the washing step. We report here that by changing the range in the electrochemical detector, plasma catecholamines were measured with only 12.5 μL of plasma and more reliably with 25 μL of plasma. The detection limit was 1 ng/mL. This assay method is very useful as blood can be collected from the tail vein in a conscious mouse and the same mouse can be used for time-dependent or age-dependent studies.

limited potentiation of blood pressure in response to oral tyramine by the anti-Parkinson brain selective multifunctional monoamine oxidase-AB inhibitor, M30

One of the limitations of non-selective monoamine oxidase (MAO) inhibitors as anti-depressant or anti-Parkinson drugs is their ability to potentiate the cardiovascular effect of oral tyramine, resulting from inhibition of systemic MAO-A and release of noradrenaline. We have investigated the cardiovascular effect of oral tyramine in response to the novel multifunctional, brain selective MAO-AB inhibitor, M30 [5-(N-methyl-N-propargylaminomethyl)-8-hydroxyquinoline], and compared it to the classical non-selective inhibitor tranylcypromine (TCP) in rats. We also measured MAO-A and B in the striatum, hippocampus, liver, and small intestine and determined brain levels of dopamine, noradrenaline, and serotonin. At the doses employed, intraperitoneal (i.p.) M30 (5 and 10 mg/kg) selectively inhibited brain MAO-A and B by more than 85%, with little inhibition of liver and small intestine enzymes while raising striatal levels of dopamine, noradrenaline, and serotonin. In contrast to TCP (10 mg/kg, i.p.), which fully inhibits both enzymes in the brain and systemic organs and significantly potentiates the tyramine pressor effect, M30 had a limited pressor effect as compared to it and controls. The limited potentiation of tyramine pressor effect by M30, its ability to raise brain levels of aminergic neurotransmitters together with its neuroprotective and neurorestorative activities make this drug potentially important as an anti-depressant and anti-Parkinsonian agent, for which it is being developed.

Effect of Phenoxybenzamine on Myocardial Cell Necroses and Blood Levels of Catecholamines in Pigs Subjected to Stress

The degree of myocardial cell necroses after stress was investigated in 6 pigs, weighing 70 to 90 kg. The stress was induced by a myorelaxant, succinylcholine, for about 12 min. The alpha-adrenoceptor blocking agent phenoxybenzamine (PBZ) was given orally 3 times a day in a total dose of 50 to 60 mg per day for 6 to 7 days before the stress. The plasma levels of noradrenaline and adrenaline were assayed in blood samples drawn before, during, and immediately after the period of stress. Heart cell necroses were found in all the cases. The activity of the sympathetic-adrenomedullary system, indicated by the plasma levels of catecholamines, was intense during the stress. When the present results were compared with those of earlier studies the degree of heart cell necroses was significantly smaller after PBZ in control pigs but significantly higher than after the beta-adrenoceptor blocking agent propranolol given for about a week. PBZ exerts a number of different actions, as briefly discussed, some of them appearing to be harmful for the heart during stress while others appear to be protective for the heart.

Resveratrol protects rat striatal slices against anoxia-induced dopamine release

Incubation of rat striatal slices in anoxic medium caused significant alterations in dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) outputs; while DA release increased several times, 50% decline in DOPAC output was observed under this condition. Tissue ATP level, on the other hand, was decreased 40% by anoxia. Presence of resveratrol in the medium decreased anoxia-induced DA release in a concentration-dependent manner. Enhanced DA output, however, was declined slightly by epicatechine and catechine, and not altered significantly by morin hydrate and quercetin dehydrate which are other penolic compounds present in the red wine. In contrary to DA output, anoxia-induced decline in tissue ATP level was not ameliorated by resveratrol. In addition to anoxia, resveratrol, as observed with DA uptake blocker nomifensine, also reduced DA release stimulated by ouabain. Efficiencies of both resveratrol and nomifensine to attenuate ouabain-induced DA output, however, were closely dependent on ouabain concentration in the medium. These results indicate that some phenolic compounds, particularly resveratrol decrease anoxia-induced DA output and appear promising agents to improve the alterations occurred under anoxic-ischemic conditions.

Stimulation of brain mast cells by compound 48/80, a histamine liberator, evokes renin and vasopressin release in dogs

Because degranulation of brain mast cells activates adrenocortical secretion (41, 42), we examined whether activation of such cells increases renin and vasopressin (antidiuretic hormone: ADH) secretion. For this, we administered compound 48/80 (C48/80), which liberates histamine from mast cells, to pentobarbital-anesthetized dogs. An infusion of 37.5 microg/kg C48/80 into the cerebral third ventricle evoked increases in plasma renin activity (PRA), and in plasma epinephrine (Epi) and ADH concentrations. Ketotifen (mast cell-stabilizing drug; given orally for 1 wk before the experiment) significantly reduced the C48/80-induced increases in PRA, Epi, and ADH. Resection of the bilateral splanchnic nerves (SPX) below the diaphragm completely prevented the C48/80-induced increases in PRA and Epi, but potentiated the C48/80-induced increase in ADH and elevated the plasma Epi level before and after C48/80 challenge. No significant changes in mean arterial blood pressure, heart rate, concentrations of plasma electrolytes (Na+, K+, and Cl-), or plasma osmolality were observed after C48/80 challenge in dogs with or without SPX. Pyrilamine maleate (H1 histaminergic-receptor antagonist) significantly reduced the C48/80-induced increase in PRA when given intracerebroventricularly, but not when given intravenously. In contrast, metiamide (H2 histaminergic-receptor antagonist) given intracerebroventricularly significantly potentiated the C48/80-induced PRA increase. A small dose of histamine (5 microg/kg) administered intracerebroventricularly increased PRA twofold and ADH fourfold (vs. their basal level). These results suggest that in dogs, endogenous histamine liberated from brain mast cells may increase renin and Epi secretion (via the sympathetic outflow) and ADH secretion (via the central nervous system).

Novel multifunctional neuroprotective iron chelator-monoamine oxidase inhibitor drugs for neurodegenerative diseases. In vivo selective brain monoamine oxidase inhibition and prevention of MPTP-induced striatal dopamine depletion

Several multifunctional iron chelators have been synthesized from hydroxyquinoline pharmacophore of the iron chelator, VK-28, possessing the monoamine oxidase (MAO) and neuroprotective N-propargylamine moiety. They have iron chelating potency similar to desferal. M30 is a potent irreversible rat brain mitochondrial MAO-A and -B inhibitor in vitro (IC50, MAO-A, 0.037 +/- 0.02; MAO-B, 0.057 +/- 0.01). Acute (1-5 mg/kg) and chronic [5-10 mg/kg intraperitoneally (i.p.) or orally (p.o.) once daily for 14 days]in vivo studies have shown M30 to be a potent brain selective (striatum, hippocampus and cerebellum) MAO-A and -B inhibitor. It has little effects on the enzyme activities of the liver and small intestine. Its N-desmethylated derivative, M30A is significantly less active. Acute and chronic treatment with M30 results in increased levels of dopamine (DA), serotonin(5-HT), noradrenaline (NA) and decreases in DOPAC (dihydroxyphenylacetic acid), HVA (homovanillic acid) and 5-HIAA (5-hydroxyindole acetic acid) as determined in striatum and hypothalamus. In the mouse MPTP (N-methy-4-phenyl-1,2,3,6-tetrahydropyridine) model of Parkinson's disease (PD) it attenuates the DA depleting action of the neurotoxin and increases striatal levels of DA, 5-HT and NA, while decreasing their metabolites. As DA is equally well metabolized by MAO-A and -B, it is expected that M30 would have a greater DA neurotransmission potentiation in PD than selective MAO-B inhibitors, for which it is being developed, as MAO-B inhibitors do not alter brain dopamine.

The neurochemical and behavioral effects of the novel cholinesterase-monoamine oxidase inhibitor, ladostigil, in response to L-dopa and L-tryptophan, in rats

The novel drugs, ladostigil (TV3326) and TV3279, are R and S isomers, respectively, derived from a combination of the carbamate cholinesterase (ChE) inhibitor, rivastigmine, and the pharmacophore of the monoamine oxidase (MAO) B inhibitor, rasagiline. They were developed for the treatment of comorbidity of dementia with Parkinsonism. In the present study, we determined the effects of these drugs on both aminergic neurotransmitter levels and motor behavioral activity in naïve and in L-dopa- or L-tryptophan-induced rats. Chronic treatment of rats with ladostigil (52 mg kg(-1) for 21 days) inhibited hippocampal and striatal MAO A and B activities by >90%, increased striatal levels of dopamine and serotonin, and inhibited striatal ChE activity by approximately 50%. Chronic TV3279 (26 mg kg(-1) for 21 days) similarly inhibited approximately 50% of striatal ChE activity, but did not affect MAO activity or amine levels. In sharp contrast to the inductive effect of the MAO A/B inhibitor, tranylcypromine (TCP), on stereotyped hyperactivity in response to L-dopa (50 mg kg(-1)) or L-tryptophan (100 mg kg(-1)), ladostigil completely inhibited these behavioral hyperactivity syndromes. Accordingly, acute rivastigmine (2 mg kg(-1)) and chronic TV3279 abolished the ability of TCP to initiate L-dopa-induced hyperactivity, while scopolamine (0.5 mg kg(-1)) reversed the inhibitory effect of chronic ladostigil on L-dopa-induced hyperactivity, suggesting that ladostigil may attenuate successive locomotion by activating central cholinergic muscarinic receptors.Finally, while chronic ladostigil administration to naïve rats resulted in preserved spontaneous motor behavior, acute treatment with ladostigil decreased motor performance, compared to control animals. In contrast, chronic as well as acute treatments with TV3279 reduced spontaneous motor activity. Thus, the aminergic potentiation by ladostigil may counteract its cholinergic inhibitory effect on spontaneous motor behavior. Our results suggest that potentiation of both aminergic and cholinergic transmission systems by ladostigil contributes equally to motor behavior performance, which is substantially impaired in comorbidity of dementia with Parkinsonism including dementia with Lewy bodies (DLB).

Are there changes in leg vascular resistance during laparoscopic cholecystectomy with CO2 pneumoperitoneum?

BACKGROUND

The prompt haemodynamic response to carbon dioxide insufflation during laparoscopic cholecystectomy suggests involvement of the sympathetic system. The aim of the present study was to examine if a change in vascular resistance in leg skeletal muscle could be an important mechanism behind the increased afterload. Furthermore, the arterio-venous differences of the catecholamines were measured in the leg before and during insufflation of carbon dioxide into the peritoneal cavity.

METHODS

Ten patients (ASA I) scheduled for laparoscopic cholecystectomy were included. After induction of anaesthesia, catheters were introduced percutaneously into the radial artery, the femoral vein and the cubital vein for pressure monitoring and blood sampling. The arterial blood flow in the legs was measured by mercury-in-Silastic strain gauge venous occlusion plethysmography. Vascular resistance in the right leg (LVR) was calculated from the formula: (MAP-FVP)/calf blood flow. Measurements were made before and 5 min after insufflation of pneumoperitoneum.

RESULTS

Induction of pneumoperitoneum increased the heart rate (P < 0.05) and also increased mean arterial pressure and femoral vein pressure as well as the calculated leg vascular resistance (P < 0.01). Calf blood flow did not change significantly in either leg. Both arterial and venous noradrenaline concentrations were higher after insufflation (P < 0.01).

CONCLUSION

In patients without heart or lung disease, pneumoperitoneum at an intra-abdominal pressure level of 11-13 mmHg increased the peripheral vascular resistance in the leg while the arterial blood flow in the leg was unaffected. Catecholamine levels increased, but were still low. Therefore, we suggest that the increase in peripheral vascular resistance is caused by increased myogenic activity in the resistance vessels secondary to increased arterial and transmural pressure rather than by increased neurogenic sympathetic activity.

Effects of norepinephrine depletion in rats during cerebral post-ischemic reperfusion

The present paper reports the effects of norepinephrine depletion in rats, after treatment with N-(2-chloroethyl)-N-ethyl 2-bromobenzylamine (DSP-4) neurotoxin, on partial cerebral ischemia and reperfusion. Histological observations made under experimental conditions of noradrenergic (NA)-depletion demonstrated that neuronal lesions were not exacerbated; in fact, in DSP-4-treated ischemic animals, a minor number of neurons appeared damaged. Our results suggest that neuronal recovery after post-ischemic reperfusion is not affected by NA-depletion. DSP-4 neurotoxin does not induce 5-hydroxy-triptamine (5-HT) depletion.

Catecholaminergic nerve fibers in bronchus-associated lymphoid tissue: age-related changes

Age-related changes of the catecholaminergic nerve fibers of the trachea, bronchial smooth muscle, lung capillaries and bronchus-associated lymphoid tissue (BALT) were studied in male Wistar rats aged 3 months (young), 12 months (adult) and 24 months (old/aged). Catecholamine histo- and immuno-fluorescence techniques were used, associated with image analysis and high pressure liquid chromatography with electrochemical detection of nor-epinephrine (nor-adrenaline). In young rats, blue-green fluorescent nerve fibers supply the trachea-bronchial smooth muscle and tracheal and bronchial glands. These structures are innervated by a delicate network of nerve fibers, being rich in varicosities. Pulmonary capillaries are sparsely innervated. The highest nor-epinephrine concentration was found in the trachea and bronchi, followed by BALT. The density and the pattern of noradrenergic nerve fibers of the trachea-bronchial tree or of the pulmonary vessels were similar in young and adult rats. In aged rats, a loss of noradrenergic nerve fibers, involving primarily the supply to the smooth muscle of the trachea-bronchial tree, was observed. Fluorescence microscopic techniques demonstrated a higher sensitivity than nor-epinephrine assay in detecting changes of the sympathetic nerve supply of the trachea-bronchial tree, pulmonary vessels and BALT. The possible significance of reduced noradrenergic nerve supply of the trachea-bronchial-pulmonary tree in aged rats is discussed.

Prevention of MPTP (N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) dopaminergic neurotoxicity in mice by chronic lithium: involvements of Bcl-2 and Bax

Lithium has been reported to exert neuroprotective activity in several neuronal cell cultures and in vivo models against glutamate toxicity. Since this action was reported to be associated with alterations in the antiapoptotic Bcl-2 family proteins, the effect of chronic lithium diet on the ability of the parkinsonism neurotoxin, N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to deplete striatal dopamine in mice was determined. Mice were fed for with a diet containing 1.1, 2.2, 3.3, and 4.4 g/kg lithium chloride (LiCl) for 4 weeks, during which time serum levels of lithium were monitored. The 3.3 g/kg lithium diet gave serum level value very similar to what is observed in lithium therapy in man and the 4.4 g/kg well above this. At the end of this period the mice received 24 mg/kg MPTP i.p. once daily for 3 days. A direct relation was established with the increase in serum lithium and its ability to prevent MPTP induced depletion of striatal dopamine (DA) and its metabolites DPOAC and HVA. With the diet containing the highest lithium concentration there was an almost complete prevention of striatal dopamine depletion and the reduction in tyrosine hydroxylase activity and protein and it prevented the increase in dopamine turnover (DOPAC + HVA/DA) normally observed in MPTP treatment. Lithium did not interfere with the metabolism of MPTP, or with its brain uptake, since, the level of its monoamine oxidase (MAO) B derived metabolite, MPP+, in the striata of lithium and non-lithium treated mice were almost identical. Striatal Bcl-2 was significantly decreased, while Bax was increased in MPTP treated mice. Lithium treatment not only increased striatal Bcl-2 in control mice, but also prevented its reduction as induced by MPTP, and an opposing effect was seen with Bax. The neuroprotective action of lithium in this model of Parkinson's disease has been attributed to its antiapoptotic activity which among other factors includes induction of Bcl-2 and reduction of Bax.

Prenatal cocaine exposure decreases nigrostriatal dopamine release in vitro: Effects of age and sex

The present study examined the effects of prenatal cocaine (PCOC) exposure, age, sex, and estrous phase on the functional development of nigrostriatal dopamine (DA) neurons. Striatal tissue was obtained from prepubescent and adult rats of both sexes after bidaily exposure to saline (1 ml/kg) or cocaine (20 mg/kg/ml saline) from embryonic days 15-21. Tissue levels, basal release, and electrically evoked (1 or 8 Hz) overflow of endogenous DA and its metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC), as well as their efflux in response to superfusion with the DA transport blocker, nomifensine (10 microM), were measured from superfused striatal slices. Generally, these measures were highest in tissue from males and adults. Tissue DA and DOPAC levels and the rate of DA turnover were unaffected by PCOC exposure. Slices from PCOC-exposed juvenile and adult male rats exhibited significantly reduced basal and electrically evoked DA release at both stimulation intensities, in conjunction with higher levels of presynaptic DA reuptake. Female rats were largely spared from the effects of PCOC exposure, and measures did not vary with estrous phase. These findings demonstrate that the effects of PCOC exposure on various parameters of nigrostriatal DA neuronal function are not uniform across age, sex, or phases of the estrous cycle. These novel alterations in nigrostriatal DA transmission are in need of independent replication, but they may have profound implications for behavioral activities regulated by these neurons and, thus, may provide a basis for sex-selective effects of PCOC in exposed humans. Possible mechanisms of deleterious effects of PCOC exposure in select groups are discussed.

Attenuation of MPTP-induced dopaminergic neurotoxicity by TV3326, a cholinesterase-monoamine oxidase inhibitor

(R)-[(N-propargyl-(3R) aminoindan-5-yl) ethyl methyl carbamate] (TV3326) is a novel cholinesterase and brain-selective monoamine oxidase (MAO)-A/-B inhibitor. It was developed for the treatment of dementia co-morbid with extra pyramidal disorders (parkinsonism), and depression. On chronic treatment in mice it attenuated striatal dopamine depletion induced by MPTP and prevented the reduction in striatal tyrosine hydroxylase activity, like selective B and non-selective MAO inhibitors. TV3326 preferentially inhibits MAO-B in the striatum and hippocampus, and the degree of MAO-B inhibition correlates with the prevention of MPTP-induced dopamine depletion. Complete inhibition of MAO-B is not necessary for full protection from MPTP neurotoxicity. Unlike that seen after treatment with other MAO-A and -B inhibitors, recovery of striatal and hippocampal MAO-A and -B activities from inhibition by TV3326 did not show first-order kinetics. This has been attributed to the generation of a number of metabolites by TV3326 that cause differential inhibition of these enzymes. Inhibition of brain MAO-A and -B by TV3326 resulted in significant elevations of dopamine, noradrenaline and serotonin in the striatum and hippocampus. This may explain its antidepressant-like activity, resembling that of moclobemide in the forced-swim test in rats.

Age-related changes in catecholaminergic nerve fibers of rat heart and coronary vessels

BACKGROUND

Age-related changes of catecholaminergic nerve fibers supplying the myocardium and the coronary vessels were studied in adult and in old rats.

OBJECTIVE

The purpose of this study was to investigate whether there are quantitative changes in myocardial and/or coronary catecholaminergic nerve fibers and related neurotransmitters.

METHODS

Samples of myocardium and/or coronary vessels were studied by means of glyoxylic acid induced fluorescence, aldehyde-induced fluorescence, and neuropeptide Y immunoreactivity. All morphological results were submitted to quantitative analysis of images. Biochemical dosage of proteins and of norepinephrine was also performed, and morphological data were compared with biochemical ones. Finally, all data were subjected to statistical analysis.

RESULTS

Our findings are indicative of an age-related decrease of all types of fluorescent sympathetic nerve fibers in rat heart and coronary arteries. Moreover, our data show that aging induces a strong decrease of norepinephrine levels in tissue homogenates of rat heart and coronary vessels. The majority of the catecholaminergic nerve fibers that show strong age-related changes are not contiguous with contractile cells of myocardium and/or of vascular wall. In fact, these fibers are located in adventitial (or epicardial) and in endothelial (or endocardial) layers.

CONCLUSION

The decrease of the catecholaminergic innervation of heart and coronary vessels of old rats can be in close relationships to the poor cardiac and/or coronary functions observed in old animals.

Occurrence of catecholaminergic nerve fibers in the human uveoscleral tissue in conditions of normal and raised intraocular pressure

The distribution of catecholaminergic nerve fibers (CNF) in human uveoscleral tissue was studied in six human eyes with normal intraocular pressure and in five eyes with increased pressure. The eyes with increased pressure had no visual field alterations and the patients did not have any glaucoma-related optic neuropathies. The amount of norepinephrine in these structures was also analysed. Catecholaminergic nerve fibers were detected by means of fluorescence microscopy and were counted using the quantitative analysis of images. Our results demonstrate that the occurrence of catecholaminergic nerve fibers (expressed in Conventional Units = C.U.) in human uveoscleral tissue is 15.4 +/- 1.6 C.U. in eyes with normal intraocular pressure. In eyes with increased intraocular pressure, these values were 12.2 +/- 1.2 C.U. Moreover, the amount of norepinephrine in tissue homogenates of the same eyes was evaluated and found to be 21.7 +/- 1.3 microg/gr tissue fresh weight of the human uveoscleral tissue in eyes with normal intraocular pressure. This value decreased to 18.8 +/- 1.1 microg/gr tissue fresh weight in the same tissue in conditions of raised intraocular pressure. In these experiments, the small number of eyes examined made it difficult to draw general conclusions. However, the role of human uveoscleral tissue was emphasized by the rich catecholaminergic innervation. A decrease of catecholaminergic nerve fibers and norepinephrine occurs when intraocular pressure is elevated. The modifications of these parameters, involved in the sympathetic control of aqueous humor outflow, may support the hypothesis of a possible relevant role for the human uveoscleral tissue in different pathological conditions.

Effect of interferon on human thymus microenvironment

Interferon, a thymic immunostimulator, was used with the aim of assessing the importance of adrenergic nerve fibers (ANF) and/or AChE-positive nerve fibers (AChENF) in the regulation of some immunological functions in humans. Thymic normal control fragments and/or thymic fragments of immunostimulated patients were removed during surgical biopsies. Thymic slices were stained with eosin-orange (for the recognition of microanatomical details of the microenvironment) and with Bodian's method for staining of nerve fibers. Histofluorescence microscopy was employed for staining ANF. AChENFs were detected by means of the direct-coloring thiocholine method. All images were submitted to quantitative morphometrical analysis and statistical comparisons of data. Moreover, the amount of proteins and noradrenaline was measured on thymic homogenates of the same patients. Treatment with interferon induces substantial changes in the thymic microenvironment, on ANF, on AChENFs and on the total amount of proteins and noradrenaline in thymic tissue homogenates. In conclusion immunostimulation with interferon induces substantial changes in the whole thymus and in its microenvironment, involving both sympathetic and parasympathetic nerve fibers.

Hypothalamic-pituitary-adrenal responses to weight loss in mice following diet restriction, activity or separation stress: effects of tyrosine

We have studied three different types of weight-loss stress caused by Diet restriction, Activity or Separation, for their effects on the hypothalamic-pituitary axis in young female mice and their responses to tyrosine 100 mg/kg/day. Plasma was assayed for ACTH and glucocorticoid determinations, and brain catecholamine concentrations were measured by HPLC/ECD. A similar weight loss of 24-28% was observed in the models despite significant differences in food intake. Diet restriction to 60% and Separation models produced a significant increase in hypothalamic noradrenaline (p < 0.01), while there was a significant decrease (p < 0.05) in the Diet restriction to 40% that was restored after tyrosine. After Activity, noradrenaline levels did not change. ACTH concentrations decreased following Diet restriction (p < 0.05) but were unaffected by Separation or Activity. The peripheral glucocorticoid response increased significantly after Activity and Diet restriction (p < 0.001), but decreased significantly after Separation (p < 0.001). Tyrosine increased glucocorticoid concentrations in the Activity and Separation models (p < 0.05), but not after Diet restriction. Despite similar weight loss in the three models there were no predictable associations between hypothalamic noradrenaline metabolism and plasma ACTH or glucocorticoid concentrations. Tyrosine might alleviate some of the different pathophysiological problems associated with the stress of weight loss.

Functional deficits following neonatal dopamine depletion and isolation housing: circular water maze acquisition under pre-exposure conditions and motor activity

Seven experiments and several behavioural tests were performed to study the effects of housing condition and experimental test conditions upon the behavioural responses and performance of adult rats neonatally treated with 6-hydroxydopamine (6-OHDA, 100 ug intracisternally, i.c.) or with vehicle. Postnatal 6-OHDA induced locomotor and total activity hyperactivity and deficits in navigational learning in a circular swim maze that were blocked by pretreatment with a dopamine (DA) reuptake inhibitor but not a noradrenaline (NA) reuptake inhibitor. Isolation-housing induced deficits in maze learning performance. Grouped housing improved the maze learning performance of 6-OHDA treated rats whereas vehicle treated rats that were isolation housed performed better following latent learning (LL) pre-exposure trials. 6-OHDA treated rats that received both Grouped housing and latent learning trials performed better on the spatial navigation task than those that received Grouped housing but no latent learning or Isolation housing and latent learning. Analysis of habituation quotients indicated marked deficits by 6-OHDA-treated rats suggesting inability to acquire this simple, nonassociative form of learning. Methylphenidate increased all three parameters of motor activity: locomotion, rearing and total activity, in both Isolation-housed and Group-housed rats from 60- to 90- or 120-min post-injection. NDO 008 induced variable and parameter-dependent effects: locomotion was elevated initially in both Isolated and Grouped rats by the compound and then reduced in the Isolated rats only whereas total activity was only elevated initially in the Isolated rats and unaffected in the Grouped rats. Rearing behaviour was reduced markedly, directly post-injection, in the Isolation-housed rats. DA, DOPAC and HVA concentrations in the striatum, nucleus accumbens, olfactory tubercle and midbrain were reduced but most markedly in the striatum. 5-Hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) concentrations were elevated in the striatum, nucleus accumbens (not 5-HIAA) and olfactory tubercle.

Neonatal 6-hydroxydopamine-induced hypo/hyperactivity: blockade by dopamine reuptake inhibitors and effect of acute D-amphetamine

Five experiments were performed to assess the changes in motor activity resulting from neonatal administration of 6-hydroxydopamine (6-OHDA) on Days 1 or 2 postnatal, at doses of either 75 or 100 micro g in a volume of 10 micro l vehicle, following pretreatment with either GBR 12909 (40 mg/kg, s.c.) or amphonelic acid (4.0 mg/kg, s.c.) or saline. Motor activity was measured either over 60-min test periods on five consecutive days of testing or at 12-min intervals within a single 60-min test session. The initial extent of locomotor hyperactivity was dependent upon the neonatal dose of 6-OHDA: the 100 micro g, but not 75 micro g, dose induced marked hyperactivity from test day 1 onwards whereas the 75 micro g dose did so from test day 3 onwards. The initial hypoactivity for rearing behaviour was observed for both doses of 6-OHDA: this hypoactivity was altered over successive test days so that by test day 5 an hyperactivity by the 75 micro g, but not 100 micro g, was observed. Pretreatment with either GBR 12909 or amphonelic acid abolished the effects of both doses of 6-OHDA. In the within-60-min test session procedure, 6-OHDA treated rats (both 75 and 100 micro g) showed initial hyperactivity for locomotion that intensified, in relation to the other groups, over each 12-min interval and initial hypoactivity for rearing that developed into hyperactivity over each 12-min interval. Pretreatment with either GBR 12909 or amphonelic acid again abolished the effects of both doses of 6-OHDA. Habituation quotients derived in each case for both procedures indicated severe habituation deficits by 6-OHDA (75 and 100 micro g) rats, compared to the control groups in all four experiments. In Experiment V, a low dose of D-amphetamine abolished the hyperactivity of 6-OHDA (75 micro g) treated rats whereas a higher dose did so only transiently. Pretreatment with GBR 12909 abolished these effects. These findings underline the neuropharmacological utility of the neonatal 6-OHDA treatment for studying brain receptor system adaptive changes underlying the respective functional alterations and as a possible laboratory model for clinical disorders.

Occurrence of adrenergic nerve fibers in human thymus during immune response

The adrenergic nerve fibers (ANF), the neuropeptide Y-like immunoreactive nerve fibers (NPY-NF) and the noradrenaline (NA) amount were studied in the human thymus in subjects previously treated or not treated with interferon therapy with the aim to identify the changes due to the interferon therapy. This therapy has been used in patients affected by multiple sclerosis (MS). Biochemical and morphological methods were used associated with quantitative analysis of images. The whole thymuses were removed during autopsies in young and adult patients not treated with interferon. Moreover, samples of thymus were removed from patients, either young or adult who had previously been treated with interferon therapy, and subjected, for diagnostic reasons, to thymic biopsy. All samples of thymus were weighed, measured and dissected. Thymic slices were stained with Eosin-orange for detection of the microanatomical details, or with Bodian's reaction for recognition of nervous structures. Histofluorescence microscopy was used for detection of ANF, and immunofluorescence microscopy for recognition of NPY-like immunoreactive structures. All morphological results were subjected to quantitative analysis of images. Noradrenaline contained in thymic structures was measured by biochemical methods. Our results only concerned the effects of the therapy and suggested that treatment with interferon therapy induces many changes in the thymic structures: (1) The protein content of thymus is significantly increased; (2) the NA content in the thymus is also significantly increased; (3) NPY-like immunoreactive structures in the thymus are significantly increased; (4) occurrence of NPY-like immunoreactivity is particularly and significantly increased both in thymic microenvironment and in structures resembling nerve fibers; (5) ANF are significantly increased in the same thymic structures in which NPY-like immunoreactivity is also increased (i.e. thymic microenvironment and structures resembling nerve fibers). The morphological and biochemical changes observed can also explain the immunological changes induced in the thymus after immunostimulating therapy.

N-(2-Chloroethyl)-N-ethyl-2-bromobenzylamine reduces intracellular calcium response to noradrenaline in rat visual cortex

Using the fluorescent indicator Fura-2, we investigated the effects of N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4), a noradrenergic neurotoxin, on intracellular calcium responses to noradrenaline, N-methyl-D-aspartate, and carbamylcholine chloride in brain slices of the rat visual cortex. Noradrenergic depletion in the visual cortex of young rats was induced by DSP-4, and its selectivity was confirmed by two different methods, i.e., immunostaining with anti-dopamine-beta-hydroxylase antibody and biochemical analysis by high-performance liquid chromatography. The treatment with DSP-4 (25 mg/kg i.p., x2) caused disruption of noradrenergic fibers throughout all cortical layers, and reduced the content of noradrenaline to 6.4% of that in the normal control. In the normal cortex, bath-applied noradrenaline (100 microM) increased the intracellular calcium to 123% of the control in terms of the F(340)/F(380) ratio of Fura-2 fluorescence. Quantitative analysis of the F(340)/F(380) ratio was performed in layers II to IV, since the increase was mainly observed in these layers. The intracellular calcium response to noradrenaline was significantly (P<0.0001) reduced in the DSP-4-treated animals to 63.2% of that in the normal control. The response to N-methyl-D-aspartate (100 microM) was also reduced, whereas the response to carbamylcholine chloride, a muscarinic cholinergic agonist (100 microM), was not affected by the DSP-4 treatment. From these findings we suggest that noradrenergic denervation by DSP-4 reduces the intracellular calcium response to noradrenaline through changes in the intracellular signal transduction.

Effects of alpha-adrenoceptor agonists in chronic morphine administered DSP4-treated rats: evidence for functional cross-sensitization

Five experiments were performed to study the effects of the Alpha-adrenoceptor agonists, clonidine and guanfacine, upon spontaneous motor activity in chronically morphine administered DSP4-treated and control rats. DSP4 (2 x 50 mg/kg, with a 10-day interval between injections) and vehicle (distilled water) were injected i.p., on each occasion 30 min after zimeldine (20 mg/kg). Morphine dosages were raised incrementally from 5 mg/kg (Days 1-3), through 10 mg/kg (Days 4-7) and 20 mg/kg (Days 8-14), to 30 mg/kg (Days 15-20). Motor activity testing occurred on Day 21, Day 22 as well as in Experiments II-V, (from 1st morphine injection). DSP4 pretreatment and chronic morphine injections each reduced motor activity during the first 30 min of testing; combined DSP4 and morphine treatment potentiated the hypoactivity. Habituation quotients indicated deficits in habituation to the novel test environment by the Vehicle-morphine (Quoteint2 only) and DSP4-morphine groups. Acute clonidine treatment (0.04 mg/kg s.c.) reduced motor activity during the first 30 min of testing but attenuated or blocked the morphine-induced hypoactivity in DSP4-treated and control rats. During the 60-90 min test period, clonidine, but not guanfacine (0.08 mg/kg), potentiated morphine-induced hyperactivity in control rats; acute clonidine enhanced this effect, whereas acute guanfacine reduced it, in the DSP4-treated rats. The enhanced hyperactivity of morphine-clonidine suggest a cross-sensitivity effect. Naloxone (0.1 mg/kg s.c.), injected after the 1st 30-min of testing, potentiated markely the clonidine-induced elevations of motor activity in morphine-administered control rats; in the DSP4-treated rats, these effects were dramatically potentiated, underlining the cross-sensitivity effect. Acute guanfacine treatment reduced motor activity during the first 30 min of testing but did not attenuate reliably morphine-induced hypoactivity in control or DSP4 rats. Naloxone did not potentiate the guanfacine-induced hyperactivity of morphine-administered control rats but induced a marked enhancement in the DSP4-treated rats, a specific case of cross-reactivity. The major findings pertain to a cross-sensitization effect of morphine upon clonidine-induced motor activity in both DSP4-treated and control rats, and to a lesser extent between morphine and guanfacine in NA-denervated rats only. The results may offer interactive implications for noradrenergic-opiate system functioning that may be of influence under neuropathological conditions.

Immunohistochemical detection of tyrosine hydroxylase and concentrations of monoamines in the substantia nigra and hypothalamus of hereditary microphthalmic rats

We compared tyrosine hydroxylase immunoreactivity in the substantia nigra and hypothalamus of hereditary microphthalmic rats with that of normal rats. A considerable number of neuronal cell bodies expressing tyrosine hydroxylase were present in the substantia nigra of the microphthalmic mutant as well as normal rats. Neuronal cells positive for tyrosine hydroxylase in the hypothalamus were fewer than in the substantia nigra in both rats. The concentrations of monoamines (dopamine, noradrenaline, adrenaline, and serotonin) in the substantia nigra and hypothalamus in the microphthalmic mutant were approximately the same as those of normal rats, although the diurnal fluctuation of a few monoamines was observed in normal rats. These results suggest that the metabolic aspects of catecholamine in the substantia nigra and hypothalamus of the microphthalmic mutant rat do not markedly differ from those of normal rats.

Interleukin 1beta as stimulator of the rat thymus

The effects of interleukin 1beta administration on the thymus of adult and old rats were studied in order to study the interactions between the nervous and immune systems and to confirm the important role played by catecholaminergic nerve fibres (CNF) in the regulation of thymic functions. Moreover, chemical sympathectomy was performed in a group of rats to study the effects on thymus of the destruction of the majority of CNF. Our results indicate that thymic stimulation (performed by means of interleukin 1beta) induces substantial changes in the fresh weight of the whole thymus, as well as in the thymic microenvironment, thymic nerve fibres, CNF, neuropeptide Y (NPY)-like positive nerve fibres and total amount of both proteins and norepinephrine in rat thymic tissue homogenates. The majority of CNF are destroyed after chemical sympathectomy with 6-OH-Dopamine (DA) and remain unchanged after treatment with interleukin 1beta.

Neuroprotective effects of MK 801 and hypothermia used alone and in combination in hypoxic-ischemic brain injury in neonatal rats

Although accumulating evidence suggests that increased extracellular glutamate concentrations may play an important role in hypoxic-ischemic brain injury, dopamine and other catecholamines also seem to be involved. The N-methyl-D-aspartate receptor antagonist MK 801 and moderate hypothermia (32-34 degrees C) are each known to be neuroprotective, but their combined effect on the release and metabolism of neurotransmitters is unknown. Seven-day-old pups (n: 150) underwent right common carotid artery ligation to induce hemispheric ischemia, and were later subjected to 120 minutes of hypoxia with 8% O2 and 92% N2O. Half the rats (Group I, n: 74) were subjected to normothermic conditions throughout the hypoxic period. Moderate hypothermia (30-32 degrees C) was induced in the other pups (Group II, n: 76) immediately after artery occlusion, and was maintained throughout the hypoxic period. Prior to inducing hypoxia, half of the rats in each group (Groups IA and IIA) received vehicle solution (0.9% NaCI) and the other rats (Groups IB and IIB) received MK 801 (0.5 mg/kg) subcutaneously at 45 and 120 minutes after occlusion. Intracerebral temperature was recorded every 15 minutes after occlusion. Infarct area (n: 40) was calculated after staining with 2% 2,3,5 triphenyltetrazolium chloride. Neuronal damage (n: 42) was assessed by quantifying CA1-CA3 neuronal loss at five hippocampal levels. The amount of damage to the monoamine system of the corpus striatum was determined based on the dopamine and 3,4 dihydroxyphenylacetic acid levels in the corpus striatum in both hemispheres (n: 46), as measured by high-pressure liquid chromatography and compared with normal control pups' values (n: 10). The normothermia/saline-treated pups had significantly larger infarct areas than the MK 801 only, hypothermia only, or MK 801/hypothermia combination groups. Neuropathological examination and striatal tissue monoamine data also confirmed marked neuronal damage in this group. Although MK 801 treatment alone resulted in significantly smaller infarct area and less tissue damage than was observed in the normothermia/saline-treated group, the moderate hypothermia and the MK 801/hypothermia combination treatment groups both exhibited better neuronal protection, especially in the corpus striatum. The rats that received combined treatment also had a significantly lower mortality rate.

Depletion of brown fat norepinephrine content by acute cold exposure and adrenoceptor blockade

Experiments were conducted to characterize the effects of acute cold exposure, with and without adrenoceptor blockade, on intrascapular brown adipose tissue (IBAT) and adrenal catecholamine content in male Sprague-Dawley rats. Groups of animals with indwelling temperature transmitters were tested following treatment with saline, the alpha-adrenoceptor blocker phentolamine, the beta-adrenoceptor blocker propranolol, combined blockade with phentolamine plus propranolol, and the ganglionic blocker chlorisondamine. IBAT norepinephrine (NE) content was not affected in animals tested at 22 degrees C, but was reduced in 4 degrees C-exposed animals treated with phentolamine (-57%), phentolamine plus propranolol (-97%), and chlorisondamine (-42%). Adrenal NE and epinephrine (EPI) content were not altered by the treatments at 4 degrees C or 22 degrees C. None of the treatments affected the temperature of animals at 22 degrees C, but significant hypothermia occurred at 4 degrees C after chlorisondamine (-2.3+/-0.3 degrees C) and the combination of phentolamine and propranolol (-1.5+/-0.4 degrees C). These results suggest that cold exposure alone did not affect IBAT NE content, but when cold exposure was combined with adrenoceptor blockade, the sympathetic activation was sufficient to cause a reduction in IBAT NE content. In addition, alpha- and beta-adrenoceptor-mediated mechanisms contribute to the maintenance of core temperature. However, both alpha- and beta-receptor mechanisms had to be interrupted before a deficit in body temperature was detected.

Effect of angiotensin-converting enzyme inhibitor on cardiopulmonary baroreflex sensitivity in patients with acute myocardial infarction

We evaluated the effect of angiotensin-converting enzyme inhibition (quinapril) on cardiopulmonary baroreflex sensitivity in 30 patients with uncomplicated myocardial infarction (quinapril group, 15 patients; placebo group, 15 patients) at 5 and 10 days after the onset of myocardial infarction. This study indicates that quinapril improved cardiopulmonary baroreflex and thus reduced sympathetic outflow in patients with acute myocardial infarction.

Adrenal medullary catecholamine secretion patterns in rats evoked by reflex and direct neural stimulation

Epinephrine (EPI) and norepinephrine (NE), secretion patterns evoked by reflex (to hypotension and hypoglycemia) and direct neural stimulation of the adrenal medulla were measured in pentobarbital anesthetized male Sprague-Dawley rats. Secretion rates were determined by collecting adrenal venous blood. Baseline catecholamine secretion was similar in innervated and denervated glands indicating that there was little tonic sympathetic neural drive to the medulla. Both hydralazine-induced hypotension and insulin-induced hypoglycemia significantly increased catecholamine secretion with the secretion of EPI predominating. Similarly, in response to stimulation of the splanchnic nerve, frequency-related increments in EPI and NE were elicited with EPI release being greater than NE at all frequencies. However, the magnitude of the increase in secretion during splanchnic stimulation at frequencies above 1 hz greatly exceeded the release achieved by reflex stimulation. The results indicate that despite the fact that the stimuli of hypotension and hypoglycemia are integrated by different centers in the brain, the pattern of adrenal release is similar.

Changes of beta-adrenergic signaling in compensated human cardiac hypertrophy depend on the underlying disease

In human heart failure, desensitization of the beta-adrenergic signal transduction has been reported to be one of the main pathophysiological alterations. However, data on the beta-adrenergic system in human compensated cardiac hypertrophy are very limited. Therefore, we studied the myocardial beta-adrenergic signaling in patients suffering from hypertrophic obstructive cardiomyopathy (HOCM, n = 9) or from aortic valve stenosis (AoSt, n = 8). beta-Adrenoceptor density determined by [(125)I]iodocyanopindolol binding was reduced in HOCM and AoSt compared with nonhypertrophied, nonfailing myocardium (NF) of seven organ donors. In HOCM the protein expression of stimulatory G protein alpha-subunit (G(s)alpha) measured by immunoblotting was unchanged, whereas the inhibitory G protein alpha-subunit (Galpha(i-2)) was increased. In contrast, in AoSt, Galpha(i-2) protein was unchanged, but G(s)alpha protein was increased. Adenylyl cyclase stimulation by isoproterenol was reduced in HOCM but not in AoSt. Plasma catecholamine levels were normal in all patients. In conclusion, both forms of hypertrophy are associated with beta-adrenoceptor downregulation but with different changes at the G protein level that occur before symptomatic heart failure due to progressive dilatation of the left ventricle develops and are not due to elevated plasma catecholamine levels.

Synthesis and release of dopamine in rat striatal slices: requirement for exogenous tyrosine in the medium

When incubated in a tyrosine-free medium, the tissue dopamine (DA) level of rat striatal slices increased by about 921 +/- 15 pmol/mg protein during 90 min of preincubation. In contrast, the tissue-free tyrosine level declined only 130 pmol/mg protein in the same assay period. Depolarization of the slices with high K+ increased both DA and DOPAC outputs and depleted tissue DA level by about 75%. Although 60 min of resting after high K+ depolarization significantly restored the tissue DA levels, neither this restoration nor depolarization-induced DA release was altered by exogenous tyrosine. Similarly, failure of exogenous tyrosine was also observed during three successive depolarization periods of striatal slices. These results indicate that nigrostriatal dopaminergic neurons are able to synthesize and release the DA in the absence of exogenous tyrosine in the medium. Since the free tyrosine level in the slices does not seem to be a sufficient source, it is likely that tyrosine mobilized from its bound source(s) supports the DA synthesis under in vitro experimental conditions.

Prenatal cocaine exposure increases serotonergic inhibition of electrically evoked acetylcholine release from rat striatal slices at adulthood

This study tests the hypothesis that prenatal cocaine (pCOC) exposure (20 mg/kg, bidaily from embryonic days 15-21) modifies 5-HT(3) receptor regulation of electrically-evoked [(3)H]acetylcholine (ACh) overflow from adult male and female (proestrus, diestrus) rat striatal slices. Also, the influence of endogenous dopamine (DA) on serotonin (5-HT) regulation of ACh overflow was determined by assessing the effects alpha-methyl-para-tyrosine (AMPT) pretreatment or sulpiride. Phenylbiguanide (PBG, 5-HT(3) agonist) superfusion dose-dependently inhibited ACh overflow in all groups except the diestrus pCOC group in which there was an enhanced sensitivity to PBG. PBG (10, 30, and 60 microM) produced greater effects in the pCOC male than in the prenatal saline (pSAL) group. The pCOC male group also exhibited greater sensitivity to PBG (30 and 60 microM) than the pCOC proestrus group. PBG inhibition of ACh overflow was comparable in the pSAL male and female (proestrus) groups. PBG inhibition of ACh overflow was greater in the pCOC diestrus group than in the pCOC proestrus (10, 30, and 60 microM), the pSAL diestrus (10 and 30 microM), and the pCOC male (10 microM) conditions. In slices from untreated rats superfused with 30 microM PBG, AMPT pretreatment (68% DA loss) reduced inhibition of ACh overflow, and 1 microM sulpiride increased ACh overflow. ICS205-930 (5-HT(3) antagonist) reduced effectiveness of PBG indicating 5-HT(3) receptor specificity for PBG. In summary, pCOC exposure enhances modulatory effects of 5-HT (via 5-HT(3) receptors) on striatal ACh release in male and females rats and the inhibitory actions of 5-HT(3) receptors are mediated by DA.