Instrumental and pharmacological paradoxical sleep deprivation in mice: strain differences.
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Animals↗
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Results for “NIALAMIDE”
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Bromocriptine enhances the behavioural effects of apomorphine and dopamine after systemic or intracerebral injection in rats.
The ergot alkaloid bromocriptine, given intraperitoneally produced dose-dependent, long-lasting stereotyped behaviour in rats which was partly antagonised by the injection of trifluoperazine into the caudate nucleus. The stereotyped behaviour produced by apomorphine (s.c.) in both naïve and catecholamine-depleted rats was significantly enhanced by prior treatment with bromocriptine (i.p.). The bilateral application of bromocriptine (2.5-40 micrograms/side in either 0.5% tartaric acid or 50% propylene glycol aqueous vehicles) to the nucleus accumbens (NAC) of rats had no effect on locomotion over a 12 hr period after injection. In contrast, another ergot alkaloid, ergometrine, dissolved in the propylene glycol vehicle, and dopamine (DA) dissolved in either of the vehicles or in saline, produced marked stimulation of locomotion. As well as being inactive after direct application to the nucleus accumbens, bromocriptine (10-160 micrograms/side) did not induce stereotyped behaviour after bilateral injection into the caudate nucleus. However, the local application of bromocriptine (10 micrograms/side) to the nucleus accumbens, while itself inactive, significantly enhanced the locomotor stimulant effect of DA (5 micrograms/side) applied to the same nucleus. The data suggest that bromocriptine is able to enhance the effects of agonists such as DA and apomorphine at DA receptors, even under conditions where bromocriptine itself is inactive.
Animals↗
Injections of deuterated tryptamine into the nucleus accumbens of the rat: effects on locomotor activity and monoamine metabolism.
Previous studies have shown that the systemic injection of tryptamine stimulates locomotion in rats and that the nucleus accumbens, a region involved in locomotion, contains the largest concentrations of binding sites for tryptamine in the brain of the rat. The present study examined the behavioral and neurochemical effects of bilateral injections into the accumbens of a deuterated analog of tryptamine, a,a-[2H]tryptamine. Injections of 25 micrograms a,a-[2H]tryptamine increased movements in rats at 25-70 min after injection and increased vertical (rearing) activity at 25-40 min. Injections of 50 micrograms of a,a-[2H]tryptamine produced a transient suppression of movement and vertical activity at 5-15 min, followed by increases in these activities at 40-65 min after injection that were comparable to the increases elicited by 10 micrograms of d-amphetamine. At 30 min after the injection of 50 micrograms a,a-[2H]tryptamine the concentration of dopamine in the nucleus accumbens was increased by 87%, and was preceded by a transient decrease in the level of the metabolite of dopamine homovanillic acid. The levels of 5-hydroxytryptamine and its major metabolite, 5-hydroxyindoleacetic acid in the nucleus accumbens were not changed. Thus, a,a-[2H]tryptamine may interact with tryptamine receptors in the nucleus accumbens to modulate locomotor behavior through mesolimbic dopamine neurons.
Animals↗
Effects of monoamine oxidase inhibitors on isoproterenol-induced cardiomegaly in rats.
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Animals↗
Effect of in vitro inorganic lead on dopamine release from superfused rat striatal synaptosomes.
The effect of inorganic lead in vitro in several aspects of [3H]dopamine release from superfused rat striatal synaptosomes was examined. Under conditions of spontaneous release, lead (1-30 microM) induced dopamine release in a concentration-dependent manner. The onset of the lead-induced release was delayed by approximately 15-30 sec. The magnitude of dopamine release induced by lead was increased when calcium was removed from the superfusing buffer. Lead-induced release was unaffected in the presence of putative calcium, sodium, and/or potassium channel blockers (nickel, tetrodotoxin, tetraethylammonium, respectively). Depolarization-evoked dopamine release, produced by a 1-sec exposure to 61 mM potassium, was diminished at calcium concentrations below 0.254 mM. The onset of depolarization-evoked release was essentially immediate following exposure of the synaptosomes to high potassium. The combination of lead (3 or 10 microM) with high potassium reduced the magnitude of depolarization-evoked dopamine release. This depression of depolarization-evoked release by lead was greater in the presence of 0.25 mM than 2.54 mM calcium in the superfusing buffer. These findings demonstrate multiple actions of lead on synaptosomal dopamine release. Lead can induce dopamine release by yet unidentified neuronal mechanisms independent of external calcium. Lead can also reduce depolarization-evoked dopamine release by apparent competition with calcium influx at the neuronal membrane calcium channel.
Animals↗
Tricyclic antidepressants: effects on extinction and fear learning.
Rats trained to run an alley for a food reward were extinguished following injections of different antidepressants. When retested several days later, the animals extinguished following pretreatment with the NE reuptake blocker protriptyline showed faster running speeds than did the other groups. Other rats given electrical shocks following pretreatment with protriptyline avoided the compartment in which they had been shocked less than did animals shocked following pretreatment with other antidepressants. This implies an interferance with some aspect of the learning or consolidation process which is correlated with the degree of NE reuptake blockage. It is hypothesized that NE terminals are deactivated following frustrative nonreward or punishment by the conversion and reuptake of the released NE to an altered extinction molecule.
Animals↗
Effects of nicotine on the exploratory locomotion patterns of female Roman high- and low-avoidance rats.
Utilizing an automated, Dashiell-type hexagonal maze, it was demonstrated that RHA rats: 1) were more active, 2) reversed direction more often, 3) entered radial (blind) alleys less often, and 4) displayed shorter latencies than did RLA rats. Direction reversals (U-turns) tended to increase from day to day with the RHA rats, whereas the opposite was true for the RLA rats. Nicotine injections (0.2 mg/kg) increased activity and the number of U-turns, shortened the latencies and lessened the likelihood of entering radial alleys for both strains. The RHA rats were more sensitive to nicotine than were the RLA rats in all of these measurements, which varied, depending upon alley length and structural complexity, among the maze configurations.
Amines↗
Effect of serotoninergic drugs on positive and negative reinforcing systems in cats.
Administration of tryptophan and 5-hydroxytryptophan produced inhibition of self-stimulation through hypothalamic electrodes which was accompanied by drowsiness and decrease of motor activity. In cats pretreated with Ro 4-4602, an inhibitor of peripheral decarboxylase, both drugs did not produce drowsiness and markedly activated self-stimulation. Both drugs prolonged the latency of the escape reaction and inhibited the punishment reaction. The data suggest an activating effect of serotonin on the system of reward and an inhibitory effect on the system of punishment.
5-Hydroxytryptophan↗
Adrenergic stimulation of the lateral hypothalamic area on sodium and potassium excretion.
The effects of adrenergic stimulation of the lateral hypothalamic area on sodium and potassium excretion were studied in rats bearing implanted cannulae. When noradrenaline was injected into several points of the lateral hypothalamic area, a dose-related increase in natriuresis and kaliuresis was observed. Rats previously injected through the same cannulae with alpha (Regitine) or beta (Propranolol) blocking agents showed different natriuretic responses when injected with noradrenaline. It was observed that the normal noradrenaline-induced natriuresis was abolished by the alpha-adrenergic blockers, while beta-adrenergic blockers increased the response. Intrahypothalamic injection of Isoproterenol, and activator of the beta-adrenergic receptor, induced a decrease in natriuresis, kaliuresis and urinary volume. In contrast, injection of Metaraminol, an alpha-adrenergic agonist, caused an increase in sodium and potassium excretion and a reduction of urinary volume. Drugs blocking the destruction of noradrenaline or its reuptake by the presynaptic nerve endings potentiated 2-fold the action of 20 nmol of noradrenaline. These experiments provide good evidence for the existence of an adrenergic mechanism consisting of alpha and beta receptors which works antagonistically on the regulation of sodium and potassium excretion. The excretion on the two electrolytes is stimulated by the alpha-adrenergic system, and inhibited by the beta-adrenergic system.
Animals↗
Effects of L-DOPA on fusimotor control of triceps surae muscle spindles in the cat.
The experiments were performed on lightly alpha-chloralose anaesthetised and spinalized cats. Alterations in fusimotor activity were assessed by recordings from single spindle afferents (90 primary and 12 secondary) from the triceps surae muscle, before and after i.v. administration of L-beta-3,4-dihydroxyphenylalanine (L-DOPA). The effects of L-DOPA on fusimotor reflexes from ipsi- and contralateral hind limb afferents were investigated by using extensions of the intact contralateral hind limb and tonic stretches of the ipsilateral posterior biceps and semitendinosus muscles as reflex stimuli. Prior to injection of L-DOPA, a low reflex responsiveness was found to both the ipsi- and the contralateral stimulation. After administration of L-DOPA, the reflex responsiveness as well as the resting activity of the muscle spindle afferents were increased as a result of enhanced activity in mainly dynamic fusimotor neurones. The results indicate that changes in fusimotor activity elicited after administration of L-DOPA are caused by release of transmission in interneuronal pathways mediating ipsi- and contralateral reflexes to mainly dynamic fusimotor neurones. The possible role of monoaminergic descending control of fusimotor neurones in the regulation of muscle tone, tremor and rigidity is discussed.
Afferent Pathways↗
Clinical features and treatment of overdosage of monoamine oxidase inhibitors and their interaction with other psychotropic drugs.
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Adult↗
Coordinated rhythmic bursting in respiratory and locomotor muscle nerves in the spinal rabbit.
In unanaesthetized, curarized spinal rabbits (C2 level) treated with Niamide and DOPA, rhythmic activities were recorded from the phrenic nerves; close coordination was observed between the phrenic bursts and the locomotor bursts which developed in hindlimb muscle nerves. The frequency of phrenic bursts was reduced after a second spinal transection at the Th12 level, while rhythms in the hindlimb remained unchanged. It thus appears that in the spinal preparation and under certain pharmacological conditions, phrenic bursts generated by the cervico-thoracic spinal cord can be driven by the lumbar generators of locomotion; spinal links thus exist between these hindlimb locomotion generators and spinal interneuronal networks involved in phrenic motoneuronal activation, may be via hindlimb forelimb driving.
Animals↗
Fluorescence histochemical evidence for decreased noradrenaline synthesis in sympathetic neurones of aged rats.
Measurements of formaldehyde-induced fluorescence of noradrenaline (NA) in sympathetic neuronal perikarya of aged (24-month) and younger (4-month) control rats revealed little or no NA fluorescence in many sympathetic neurones of aged rats: neuronal fluorescence in younger rats was substantially greater. Monoamine oxidase inhibition increased NA fluorescence in all rats, but the increase was greater in the 4-month controls. Reserpine administration caused an almost complete disappearance of NA fluorescence after 12 h. However, normal NA levels were restored in the 4-month controls after 48 h but not for 7 days in the aged rats.
Age Factors↗
Relationship between phrenic and hindlimb extensor activities during fictive locomotion.
In decorticate and in spinal curarized rabbit preparations, respiratory and locomotor rhythms can be closely related (1:1 coupling between successive periods), demonstrating central relationships between the two types of pattern generators. In both preparation types, phrenic discharges are highly correlated to the extensor activities.
Action Potentials↗
Characterization of dopamine autoreceptors in the amygdala: a fast cyclic voltammetric study in vitro.
The present study has employed the technique of fast cyclic voltammetry to measure electrically-evoked dopamine release within the central amygdaloid complex in a rat brain slice. Local electrical stimulation caused the release of an electroactive substance which was identified, biochemically and pharmacologically, as being neuronal dopamine. Dopamine release could be inhibited by the dopamine D2 receptor agonist, quinpirole, but not by the D1 receptor agonist, SKF38393. Quinpirole-induced inhibitions were antagonized by sulpiride, metoclopramide and clozapine but not by SCH23390. It is concluded that dopamine release in the amygdala can be modulated by presynaptic D2 receptors which appear to be the same type as those found in striatum and nucleus accumbens.
2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
The effects of 5-hydroxytryptamine depletors and monoamine oxidase inhibitors on color changes of the fiddler crab, Uca pugilator: further evidence in support of the hypothesis that 5-hydroxytryptamine controls the release of red pigment-dispersing hormone.
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Acclimatization↗
5-hydroxytryptamine and the mediation of pituitary-adrenocortical hormones in the extinction of active avoidance behaviour.
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Adrenal Cortex↗
Thin-layer chromatography of hydrazidic monoamine oxidase inhibitor drugs.
Seven solvent systems for the thin-layer chromatographic separation of hydrazidic monoamine oxidase inhibitor drugs have been developed. Detection of compounds at the microgram level was performed with the aid of thirteen spray reagents.
Chromatography, Thin Layer↗