A selective inhibitor of serotonin uptake: Lilly 110140, 3-(p-trifluoromethylphenoxy)-N-methyl-3-phenylpropylamine

Lilly 110140 is a highly selective inhibitor of serotonin uptake into synaptosomes of rat brain, unlike previous monoamine uptake inhibitors that also inhibit the uptake of norepinephrine and dopamine. Lilly 110140 should be useful in studying the function of serotoninergic neurons and may be helpful in clariying the role of serotonin in certain types of mental depression.     

dl-N-methyl-3-(o-methoxyphenoxy)-3-phenylpropylamine hydrochloride, Lilly 94939, a potent inhibitor for uptake of norepinephrine into rat brain synaptosomes and heart.

dl-N-Methyl-3-(o-methoxyphenoxy)-3-phenylpropylamine hydrochloride, Lilly 94949, is a potent inhibitor for uptake of norepinephrine (NE) into synaptosomes of rat brain with inhibitor constant (Ki) value of 1.8 × 10⁻⁷M. Lilly 94939 profoundly reduces the $\text{in vivo}$ accumulation of radioactivity from labeled NE in heart with ED₅₀ value of 1.5 mg/kg i.p. The inhibitory effects of the compound in synaptosomes and heart are most profound within 15 min of an intraperitoneal injection of Lilly 94939 at 10 mg/kg but much deminished at the 4th hr. These properties are in great contrast with its trifluoromethyl analog, Lilly 110140, which has previously been reported as a selective inhibitor of serotonin uptake in synaptosomes and without any effect on the accumulation of radioactivity from labeled NE in heart.     

Behavioral depression in pigeons following L-tryptophan administration

Since elevations of serotonin (5-HT) content in brain have been related to the behavioral depression which follows administration of 5-hydroxytryptophan (5-HTP) to pigeons emitting a food-reinforced learned response, injections of L-tryptophan (100, 200, and 300 mg/kg I.M.), which is partially metabolized to 5-HT, were given to pigeons working on the same behavioral schedule. Qualitatively similar, but shorter, periods of disrupted behavior followed. As is also the case with 5-HTP, pretreatment with 50 mg/kg iproniazid, a monoamine oxidase inhibitor, increases the duration of behavioral depression following L-tryptophan. Pretreatment with 10 mg/kg Lilly 110140, a new highly selective inhibitor for uptake of 5-HT into synaptosomes, also enhanced L-tryptophan induced depression. Initial neurochemical studies indicate that the elevated levels of 5-HT in the telencephalon after an injection of L-tryptophan follow the time course of the depressed behavior. These data support the suggestion that the release of 5-HT plays a role in certain types of behavioral depression.     

Evidence indicating participation of the serotonergic system in controlling feeding behavior in Coturnix japonica (Galliformes: Aves).

We investigated participation of the brain serotonergic system in food intake control by using oral and systemic administration of serotonin precursors in quails (Coturnix japonica). Dietary supplemental tryptophan (0.1-50.0 g/kg) provoked a dose-dependent inhibition of food intake during a 5-h observation period, which persisted up to 24 h for doses of 30.0 and 50.0 g/kg. Normally fed and fasted animals treated with hydroxytryptophan (12.5-50.0 mg/kg) by the intracoelomic route showed an acute inhibition of food intake. Hypophagia in fasted birds was only effective when the precursor was administered immediately before food presentation. A similar response was obtained by administering serotonin (0.125-2.5 mg/kg, sc), with animals showing a hypnogenic response within the first ten minutes after administration, suggesting that, in contrast to mammals, the amine crosses the blood-brain barrier in quails. Administration of hydroxytryptophan at all doses tested induced significant dipsogenic behavior despite the concomitant hypnogenic response. The results suggest the involvement of serotonergic pathways in food intake control in quails and also show, for the first time, hypnogenic action induced by serotonin and a hyperdipsic effect elicited by hydroxytryptophan.     

Metabolic responses to catecholamines in dogs injected with a single dose of triiodothyronine.

Lipolytic and glycogenolytic responses to catecholamine infusions were studied in resting dogs before and 20 h following administration of a single dose (0.1 mg/kg) of triiodothyronine (T3). In the dogs pretreated with T3 much higher increases in the plasma FFA concentration were found both during noradrenaline and adrenaline infusions in comparison with control experiments. Adrenaline-induced increases in blood LA and glucose levels were also significantly higher in T3-pretreated dogs than in controls. The blockade of beta-adrenergic receptors with propranolol prevented the increases in blood FFA and LA concentrations during subsequent adrenaline infusion. Phentolamine -- the alpha-adrenergic blocking agent -- infused to the T3-pretreated dog inhibited the adrenaline-induced rise in blood glucose level. The observed changes in the metabolic responses to catecholamines induced by triiodothyronine pretreatment indicate that at least in the dog this hormone potentiates both the lipolytic and glycogenolytic effects of catecholamines acting on appropriate adrenergic receptors.     

Protection afforded by allopurinol in the first 24 hours of coronary occlusion is diminished after 48 hours

Experiments were performed to test whether the reduction in infarct size afforded by allopurinol following 24 h of permanent coronary artery occlusion is sustained over the subsequent 24 h. A dog's coronary artery was occluded with an embolus followed by injection of radiomicrospheres into the left ventricle to mark the ischemic region and to measure regional blood flow. Dogs were sacrificed either 24 h or 48 hours after embolization. The infarcts were delineated by failure to stain with triphenyl tetrazolium chloride and the ischemic zones were visualized by autoradiography of the heart slices. Dogs in the treatment groups received 600 mg of allopurinol PO 18 h before surgery, and a 10 mg/kg IV bolus 15 minutes before embolization followed by constant IV infusion of 55 mg/kg/24 h until sacrifice. A close correlation in the control animals between the percent of the ischemic zone which infarcted and collateral blood flow was used to predict a nonintervention infarct size in each treatment animal. Allopurinol treatment caused 17.9 +/- 3.3% less of the risk zone to be tetrazolium negative after 24 hours of ischemia than that seen in untreated animals. Less allopurinol induced salvage was observed in the 48 hour drug group with only a 11.1 +/- 3.3% limitation in infarct size. Furthermore, the effect was inconsistent at 48 h with only 2 dogs showing salvage. We conclude that allopurinol delays but does not prevent infarction in the permanent occlusion model.     

The effect of a serotonin uptake inhibitor (Lilly 110140) on the secretion of prolactin in the rat

Serotonin reuptake inhibitor 3-(p-trifluoromethylphenoxy)-N-methyl-3-phenylpropylamine (Lilly 110140) in a dose of 10 mg/kg i.p. had no effect on the resting levels of serum prolactin in normal male rats. However, pretreatment of the animals with this drug strongly potentiated the prolactin releasing effect of 5-hydroxytryptophan as well as the prolactin release induced by ether stress and blood withdrawal. These results indicate that a central serotoninergic mechanism is involved in the stress-induced prolactin release in the rat.     

Effect of fluoxetine and metergoline on amphetamine-induced rise in plasma corticosterone

The effect of the serotonin reuptake inhibitor, fluoxetine, and the serotonin antagonist, metergoline, on the rise in plasma corticosterone induced by amphetamine was studied in the conscious, unrestrained rat. Fluoxetine (2.5 mg/kg) did not affect plasma corticosterone. However, this dose of fluoxetine when administered two hours prior to amphetamine (0.1 or 0.5 mg/kg) significantly potentiated the amphetamine-induced rise in plasma corticosterone. Fluoxetine had no effect on the response induced by the highest dose of amphetamine (1.0 mg/kg) utilized in the study. In contrast, metergoline produced a dose-dependent increase in plasma corticosterone over the range 0.1 – 5.0 mg/kg. This response reached maximum 30 minutes after drug administration and had a duration of approximately 120 minutes. Pretreatment of animals with metergoline (5.0 mg/kg) three hours before the administration of amphetamine (1.0 mg/kg) resulted in a significant decrease in the corticosterone rise induced by amphetamine. Lower doses of metergoline were ineffective in reducing the amphetamine-induced response. These observations support the hypothesis that the amphetamine-induced rise in plasma corticosterone is due, in part, to stimulation of serotonergic neurons.     

The blockade of serotonin uptake into synaptosomes:relationship to an interaction with monoamine oxidase inhibitors.

To test the hypothesis that the hyperpyrexia produced by meperidine and detromethorphan in rabbits pretreated with a monoamine oxidase inhibitor is related to inhibition of neuronal uptake of serotonin (5-hydroxytryptamine (5-HT)), fluoxetine (Lilly 110140) was studied. This potent and specific 5-HT neuronal uptake blocker was administered to phenelzine-pretreated rabbits and found to produce a lethal hyperpyrexia in doses equal to or greater than 2.5 mg/kg. The order of potency in blocking 5-[14C]HT uptake into synaptosomes prepared from rabbits was: fluoxetine greater than meperidine = dextromethorphan = levorphanol greater than anileridine greater than alphaprodine greater than morphine. Since fluoxetine, meperidine, and dextromethorphan produce hyperpyrexia in phenelzine-pretreated rabbits, whereas anileridine, alphaprodine, and morphine do not, there appears to be some correlation between the hyperpyrexic response and inhibition of 5-HT uptake. The exception is levorphanol, which is not hyperpyrexic despite being equipotent with meperidine and dextromethorphan in inhibiting 5-HT uptake. The ineffectiveness of levorphanol in producing hyperpyrexia may be due to its marked depressant properties, since the addition of another depressant drug (pentobarbital) antagonized the hyperpyrexic effect of meperidine.     

L-tryptophan attenuation of the dopaminergic and behavioral responses to cocaine.

This study assessed the effects of acute intravenous L-tryptophan (neutral amino acid precursor for serotonin) administration on cocaine-induced dopaminergic responses. Male Sprague-Dawley rats were surgically implanted with guide cannulas in the nucleus accumbens 5 days prior to the study and with vascular catheters (carotid artery and jugular vein) on the day prior to the study. Using microdialysis, extracellular nucleus accumbens dopamine levels were measured in freely moving rats. Following a 2 h equilibration period, animals were randomized (n=7-8 per group) to receive either a constant intravenous (IV) infusion of L-tryptophan (200 mg/kg/h) or an equal volume (2 ml/h) of saline. Ninety minutes into the infusion, cocaine (20 mg/kg) was injected intra-peritoneally. Cocaine increased nucleus accumbens microdialysate dopamine levels (500% at 30 min). This was associated with marked hyperactivity. Tryptophan infusion elevated plasma tryptophan (8-fold), and blunted the cocaine-induced increase in nucleus accumbens microdialysate dopamine levels by approximately 60%. Furthermore, tryptophan attenuated the cocaine-induced locomotor activity. These neurochemical and behavioral effects of tryptophan were associated with a marked increase in brain tissue serotonin content. The results of these studies demonstrate the feasibility of acute dietary manipulation of neurochemical and behavioral responses to cocaine. The duration, adaptation and tolerance to these effects remain to be elucidated.     

Effects of short- and long-term neuroleptic treatment on brain serotonin synthesis and turnover: focus on the serotonin hypothesis of schizophrenia

Short-term (90 min) administration of haloperidol (2 mg/kg), or chlorpromazine (10 mg/kg) increased the activity of tryptophan hydroxylase as well as the levels of 5-hydroxytryptamine (serotonin) and 5-hydroxyindoleacetic acid in mid-brain of rats. The chronic neuroleptic treatment (21 days) produced more pronounced changes in all parameters related to serotonin synthesis and turnover. The activity of tryptophan hydroxylase in mid-brain was further augmented; the levels of 5-hydroxytryptamine and 5-hydroxyindole-acetic acid were significantly elevated not only in mid-brain, but also in several other discrete regions examined. These data suggest that neuroleptics enhance the synthesis and utilization of brain serotonin. The role of brain serotonergic neurons in the pathophysiology of schizophrenia is further considered.     

Rat Brain Norepinephrine Metabolism: Substantial Clearance Through 3,4-Dihydroxyphenylethyleneglycol Formation

To assess whether the metabolic clearance of rat brain norepinephrine (NE) through 3,4-dihydroxyphenylethyleneglycol (DHPG) formation is quantitatively comparable or greater than through 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) production, we studied the accumulation rates of conjugated DHPG and MHPG following probenecid administration in whole brain as well as in several brain regions. Administration of increasing doses of probenecid (100-500 mg/kg, i.p.) 1.5 h before sacrifice produced a dose-dependent increase of conjugated DHPG and MHPG levels. The maximum increment of these conjugated metabolites occurred at a dose of 300 mg/kg or higher. During the first hour following probenecid administration (300 mg/kg, i.p.), rat brain conjugated DHPG and MHPG levels accumulated linearly at a rate of 646 and 319 pmol/g/h, respectively. With the probenecid technique, the estimated appearance rates of conjugated DHPG significantly exceeded those of conjugated MHPG in hypothalamus, midbrain, brainstem, hippocampus, and cerebral cortex. These results clearly indicate that under resting conditions, formation and efflux of conjugated DHPG is the major route of metabolic clearance of rat brain NE.     

Alloxan-induced diabetes in the rat - protective action of (-) epicatechin?

Administration of alloxan (150 mg/kg body weight, i.p.) to male Wistar rats induced a reproducible and persistent diabetes mellitus as evidenced by elevated serum glucose and low serum insulin concentrations. Administration of either (-)epicatechin or (+)catechin (250 mg/kg, i.p. on each occasion) at 36, 24, 12 and 1 hour before and at 12 and 24 hours after alloxan administration did not prevent the induction of the diabetes. Similarly, treatment of animals with (-)epicatechin or (+)catechin (125 mg/kg i.p. twice daily) for 21 days commencing 24 hours after alloxan administration did not reverse the peristing elevated serum glucose and low serum insulin concentrations. Moreover, administration of these compounds did not relieve any of the symptoms of the alloxan-induced diabetes such as poor weight gain, polyuria or polydipsia.     

Inhibition of rat liver tryptophan pyrrolase activity and elevation of brain tryptophan concentration by administration of DL-alpha-amino-beta-pyridinepropanoic acid (pyridylalanine) analogs

Single doses of DL-alpha-amino-beta-(2-pyridine)propanoic acid (2-PA, 100 mg/kg) significantly decreased the holoenzyme and apoenzyme activities of rat liver tryptophan pyrrolase (TP) and increased brain tryptophan, serotonin (5-HT) and 5-hydroxyindole-3-ylacetic acid concentrations. 2-PA had no inhibitory effect on either of the enzyme activities in vitro, but its expected metabolites were effective. Single doses of DL-alpha-amino-beta-(3-pyridine)propanoic acid (3-PA, 100 mg/kg) decreased only the holoenzyme activity and elevated brain tryptophan and its metabolites levels in rats. 3-PA and its metabolite, 3-pyridylpyruvate, inhibited only the holoenzyme activity in vitro. DL-alpha-Amino-beta-(4-pyridine)propanoic acid (4-PA) caused significant changes in liver TP (holo- and apoenzyme forms) activity and brain tryptophan concentration only after repeated administration (100 mg/kg/day). 4-PA was a weak inhibitor of the holoenzyme, but its metabolites apparently inhibited the holo- and apoenzyme activities in vitro. These findings suggest that PA analogs (and/or their metabolites) increased brain tryptophan (and hence 5-HT synthesis) by directly inhibiting liver TP activity.     

Cerebral serotonin and the hypothalamo-hypophyseal-adrenal system of the rat during aging]

The role of brain serotonin (5HT) on the hypothalamus-pituitary-adrenal system (HPAs) under basal condition and after injections of p-chlorophenylalanine (pCPA) and L-5-hydroxytryptophan (L-5HTP) has been studied in 6, 12 and 28 month old male Wistar rats. Four experimental groups were made for each age: control, saline, injected with pCPA (250 mg/kg i.p.) and L-5HTP (200 mg/kg i.p.), the effects being valued 2 hours after L-5HTP administration and 24 hours after pCPA injection. In all groups the plasmatic ACTH, the corticosterone levels as well as the simultaneous changes of the 5TH content tryptophan hydroxylase activity in whole brain were estimated two hours after the L-5HTP injection and 24 hours after that of pCPA. Significant changes are not found in the plasmatic ACTH and corticosterone values with respect to age under basal condition. Nevertheless, the response of HPAs differs with the age after pCPA or L-5HTP injection. The ACTH and corticosterone levels augment by L-5HTP and decrease by pCPA in all age groups, but this corresponding increase or decrease was less marked in the older rats. The 5HT content as tryptophan hydroxylase activity in brain decreased in old animals. pCPA and L-5HTP determine, respectively, high falls and rise of 5TH values, these changes being more intense for pCPA in old rats and for L-5HTP in young and mature animals. The tryptophan hydroxylase activity is decreased by pCPA as L-5HTP injections.(ABSTRACT TRUNCATED AT 250 WORDS)     

对乙酰氨基酚诱导的小鼠药物性肝损伤的模型研究

改良对乙酰氨基酚（acetaminophen,APAP）单独诱导小鼠急性肝损伤的模型和致死模型。随机将小鼠分为4组：空白对照组、APAP3h组、APAP6h组和APAP12h组,每组5只。饥饿15h后用对乙酰氨基酚诱发小鼠肝损伤。测定各组血清ALT、AST及胆红素含量,HE染色观察各组肝组织损伤情况。观察生存率时,小鼠随机分为对照组、禁食＋APAP（500mg／kg）组、禁食＋APAP（300mg／kg）组和不禁食＋APAP（500mg／kg）组,四组同时给药,然后记录各组小鼠的生存情况,绘制四组小鼠的生存曲线。小鼠注射APAP后,随时间的延长,ALT、AST水平逐渐升高,均明显高于空白对照组（P〈0．05）。小鼠肝脏HE染色可见,APAP中毒组小鼠肝细胞坏死及炎性细胞浸润。禁食＋APAP（500mg／kg）组小鼠自16h开始出现死亡,72h时全部死亡,死亡率明显高于不禁食组和禁食＋APAP（300mg/kg）组小鼠。该研究对APAPI起的C57／BL6小鼠药物性肝损伤模型进行改良,使其更加稳定和便于研究,为进一步探究APAP诱导肝毒性的机制及防治措施奠定了基础。     

Enhancement in extracellular serotonin levels by 5-hydroxytryptophan loading after administration of WAY 100635 and fluoxetine

It has been demonstrated that synthesis of serotonin (5-HT) is dependent on the availability of precursor, as well as the activity of 5-HT neurons. In the present series of experiments, we examined the effects of precursor (5-HTP) loading on extracellular hypothalamic 5-HT after administration of fluoxetine alone or in combination with WAY 100635, a selective 5-HT1A antagonist. In the first experiment, fluoxetine alone (10 mg/kg i.p.) caused 5-HT levels to significantly increase to 150% of basal levels. Subsequent administration of 5-HTP at 10, 20, and 40 mg/kg i.p. caused 5-HT levels to further increase to a maximum value of 254%, 405%, and 618%, respectively. In the second experiment, either vehicle or WAY 100635 (1 mg/kg/hour s.c.) was infused, then fluoxetine (10 mg/kg i.p.) and 5-HTP (10 mg/kg i.p.) were administered. By itself, WAY 100635 led to a slight but significant increase in hypothalamic 5-HT levels one hour after the start of administration (130% of basal levels). In the WAY 100635-treated group, fluoxetine caused an increase to 240% of basal levels after one hour, which rose to 290% of basal levels after two hours. Subsequent administration of 5-HTP further increased 5-HT levels to 580% of basal levels after one hour. In the vehicle-treated group, fluoxetine caused an increase of 160% of basal levels which was stable over two hours, and subsequent administration of 5-HTP led to a slight increase in 5-HT levels of 220% after one hour. These results suggest that combining blockade of 5-HT1A autoreceptors with 5-HT uptake inhibition results in a synergistic increase in synthesis and release of 5-HT when precursor is administered.     

Inhibition of serotonin reuptake.

An uptake system on the serotonin neuronal membrane apparently functions to inactivate serotonin that has been released into the synaptic cleft. Various inhibitors of this active transport system on serotonin neurons are known, and some are specific in the sense that they do not inhibit the active uptake system on norepinephrine neurons. The most widely studied specific inhibitor of the serotonin neuron pump is fluoxetine, 3-(p-trifluoromethylphenoxy-N-methyl-3-phenyl propylamine (Lilly 110140). When fluoxetine or other effective but less specific serotonin uptake inhibitors are given, a rapid decrease in serotonin turnover occurs and the rate of firing of single neural units in the serotonin rich raphe area of brain is reduced. This decrease in serotonin turnover and release may be a compensatroy mechanism in response to an enhanced action of serotonin on synaptic receptors. Through the use of fluoxetine and other serotonin uptake inhibitors, the role of serotonin neurons in various brain functions--behavior, sleep, regulation of pituitary hormone release, thermoregulation, pain responsiveness, and so on--can be studied.     

Effect of inhibiting prostaglandin synthesis on edema formation and albumin leakage during thermal trauma in the rat

Prostaglandins (PGs) participate in the inflammatory response, but the contribution of endogenously synthesized PGs to edema formation and increased vascular permeability is not known. Using a 10% scald burn in the rat, we measured water content (as percent, wet minus dry/wet weight) and 131I-RISA leakage (counts/g dry tissue) in scalded and normal skin at 30 minutes and 3 hr post injury. Four groups (10 rats/group) in each time period studied: control; scald; scald, 5 mg/kg indomethacin; scald, 10 mg/kg indomethacin. Indomethacin was administered intravenously 30 minutes before the scald; RISA was injected intravenously 30 min before termination of the study. In all indomethacin-treated groups immunoreactive plasma PGA was significantly lower (p less than 0.05) than in scalded, untreated groups. All scalded groups showed significantly higher RISA counts and water content than did the control group (p less than 0.01). At 30 min post-injury the indomethacin -treated groups did not differ from the untreated scald group (p greater than 0.20). In the 3 hour study all scalded groups had significantly higher content and RISA counts than control (p less than 0.01). Thus PGs produced during thermal trauma do not greatly contribute to the edema formation and increase in vascular permeability.     

Etude clinique préliminaire sur l'emploi de la dihexyvérine en obstétrique

This study attempted to evaluate the effect of dihexyverine HCl (Metaspas), an anticholinergic and direct smooth muscle relaxant (spasmolytic), in shortening the first stage of labour. One hundred and five patients constituted the series: 31 were primiparae, 27 secundiparae and 47 multiparae. The majority of these (95) received one intramuscular injection (10 mg.) of dihexyverine. Alphaprodine (Nisentil), 40 mg., was administered in all but 10 cases, since dihexyverine has no analgesic action. Seventy-five control patients were used: 25 were primiparae, 25 secundiparae and 25 multiparae. Alphaprodine alone was administered to these control patients. The length of time for dilatation from 4 cm. to 10 cm. was the selected criterion. In the control group, the average time for complete cervical dilatation was 4 hours, 10 minutes. In the group treated by dihexyverine, complete dilatation was achieved in 1 hour, 16 minutes. On the average, the first stage of labour was 2 hours and 54 minutes shorter with dihexyverine; the clinical effect begins 10-30 minutes after administration. The only side effect encountered was a skin rash in one patient.