A9 and A10 dopamine nuclei as a site of action for effects of 8-OH-DPAT on locomotion in the rat.

The 5-hydroxytryptamine (5-HT) 5-HT(1A) receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) was applied locally (0-5 microg bilaterally) into either the substantia nigra (A9) or the ventral tegmental area (A10) of adult male Wistar rats, and 10 min later spontaneous motor activity was observed in an open field ( approximately 0.5 m(2)) for 30 min. The rate of dopamine synthesis was estimated in neostriatal areas, the amygdala, and the prefrontal cortex, by measuring the accumulation of DOPA, following inhibition of cerebral decarboxylase by means of 3-hydroxybenzylhydrazine (NSD-1015).

In vivo characterization of novel full and partial 2-(4-aminophenyl)-N,N-dipropylethylamine dopamine D(2) receptor agonists.

Behavioral and biochemical techniques were used to compare the in vivo intrinsic efficacy of two new 2-(4-aminophenyl)-N, N-dipropylethylamine dopamine D(2) receptor agonists, 2-(4-amino-3-trifluoromethylphenyl)-N-N-dipropyl-ethylamine (NBF-203) and 2-(4-amino-3-bromo-5-trifluoromethylphenyl)-N-N-dipropylethylamine (NBF-234). Adult male Sprague-Dawley rats were used as experimental animals. NBF-203 was characterized as a full dopamine D(2) receptor agonist, whereas NBF-234 displayed properties of a partial agonist, or antagonist, at dopamine D(2) receptors.

Improved conditioned avoidance learning by oxytocin administration in high-emotional male Sprague-Dawley rats.

Objective: To examine anti-stress-like properties of oxytocin as a means to improve conditioned avoidance learning in a low-performing, high-emotional, stock of Sprague-Dawley male rats.

Methods: Adult male rats of two stocks of the Sprague-Dawley strain, designated Stock A and Stock B, were treated daily with oxytocin (1 mg kg(-1) s. c.

Building neural representations of habits.

Memories for habits and skills ("implicit or procedural memory") and memories for facts ("explicit or episodic memory") are built up in different brain systems and are vulnerable to different neurodegenerative disorders in humans. So that the striatum-based mechanisms underlying habit formation could be studied, chronic recordings from ensembles of striatal neurons were made with multiple tetrodes as rats learned a T-maze procedural task. Large and widely distributed changes in the neuronal activity patterns occurred in the sensorimotor striatum during behavioral acquisition, culminating in task-related activity emphasizing the beginning and end of the automatized procedure.

Oxytocin as a possible mediator of SSRI-induced antidepressant effects.

The nonapeptide oxytocin is released into systemic circulation in situations of psychosocial interaction, and has been shown to be involved in mechanisms of social bonding and social recognition in laboratory studies. In view of disturbances in psychosocial relationships being a triggering factor for depression and anxiety, it is interesting to note that experimental studies have shown oxytocin to possess antidepressant- and anxiolytic-like actions. Thus.

In vivo effects of remoxipride and aromatic ring metabolites in the rat.

The in vivo effects of remoxipride, in relation to some of its identified metabolites, were investigated in adult male Sprague-Dawley rats. The methods used included: (1) estimation of the in vivo rate of brain monoamine synthesis by measuring the accumulation of dihydroxyphenylalanine and 5-hydroxytryptophan after decarboxylase inhibition; (2) observations of spontaneous locomotor activity in a photocell-equipped open-field arena ( approximately 0. 5 m2); (3) treadmill locomotion ( approximately 4 m min-1); (4) inclined grid (60 degrees ) catalepsy test; (5) d-amphetamine-induced (1.

Sexual motivation promotes oxytocin secretion in male rats.

The present study examines plasma oxytocin levels in relation to performance of copulatory behavior in male rats. The animals were divided into three groups: A) home-cage controls, B) sexually naive and C) sexually experienced. Following 15 min of sexual interactions with a sexually proceptive female, brought into estrus by sequential injections of estradiol benzoate (12.

Effects of selective serotonin and dopamine agonists on plasma levels of glucose, insulin and glucagon in the rat.

Male Sprague-Dawley rats were given one of the 5-HT receptor agonists 8-OH-DPAT (0.5-2.0 mg kg-1), TFMPP (0.

Evidence for specific involvement of 5-HT1A and 5-HT2A/C receptors in the expression of patterns of spontaneous motor activity of the rat.

The 5-HT1A and the 5-HT2A/C receptor agonists 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) (0.006-0.4 mg kg-1 s.

Effects of 5-HT agonists, selective for different receptor subtypes, on oxytocin, CCK, gastrin and somatostatin plasma levels in the rat.

Adult male Sprague-Dawley rats were administered the 5-HT subtype selective receptor agonists 8-OH-DPAT (0.5-2.0 mg/kg), buspirone (2-8 mg/kg) (5-HT1A), TFMPP (0.

Suggestive evidence for a DA D3 receptor-mediated increase in the release of oxytocin in the male rat.

The dopamine (DA) D2/3 receptor agonists quinpirole (0.5-8.0 mg kg-1, s.

Stimulation of median, but not dorsal, raphe 5-HT1A autoreceptors by the local application of 8-OH-DPAT reverses raclopride-induced catalepsy in the rat.

The local application of 8-OH-DPAT (0.5 or 2.5 micrograms/rat, 10 min) into the median, but not the dorsal, raphe nucleus resulted in a reversal of the catalepsy induced by the DA D2 receptor blocking agent raclopride (16 mg kg-1 s.

High doses of oxytocin cause sedation and low doses cause an anxiolytic-like effect in male rats.

The aim of the present investigation was to explore dose relationships for effects of oxytocin on spontaneous motor activity in the rat. Oxytocin in doses from 1-1000 micrograms/kg was given SC to male Sprague-Dawley rats, and spontaneous motor behavior was measured by means of photocell-operated open-field observations. In the rats treated with low doses of oxytocin (1-4 micrograms/kg), there was a decrease in peripheral locomotor activity.

Time course for synchronization of spontaneous locomotor activity in the rat following reversal of the daylight (12:12 h) cycle.

The present results demonstrate that 5-7 days on a reversed light-dark cycle (12:12 h) is sufficient for the synchronization of spontaneous locomotor activity with the new circadian rhythm in rats. Once established, the circadian rhythm is stable for at least 3 days under constant illumination conditions. Reversal of the light-dark cycle appears to be both a reliable and practical procedure in everyday laboratory work.

Effects of exposure to an estrous female on forebrain monoaminergic neurotransmission in the non-copulating male rat.

Regional changes in the rate of brain monoamine synthesis were monitored in male rats exposed to, but prevented from physical contact with, an estrous or an ovariectomized female. The in vivo rate of tyrosine and tryptophan hydroxylase activities were estimated by measuring the accumulation of DOPA and 5-HTP following inhibition of cerebral aromatic L-amino acid decarboxylase by means of 3-hydroxybenzylhydrazine (NSD-1015) treatment (100 mg/kg i.p.

Effects of 5-HT1A receptor agonists on patterns of rat motor activity in relation to effects on forebrain monoamine synthesis.

The effects of the 5-HT1A receptor agonists 8-OH-DPAT (0.15-2.5 mumol kg-1 subcutaneously), flesinoxan (0.

Supraspinal mediation of dopamine-serotonin interactions in extrapyramidal motor functions in the rat.

The effects of intracerebroventricularly (i.c.v.

Substance P injection into the dorsal raphe increases blood pressure and serotonin release in hippocampus of conscious rats.

Microinjections of substance P (SP, 100 pmol) into the dorsal raphe nucleus (DRN) in conscious rats increased blood pressure and heart rate for 30-40 min. Concomitantly, the extracellular levels of 5-hydroxytryptamine (5-HT) in the ventral hippocampus, monitored by microdialysis, increased by 30% for 20 min compared with the vehicle control. Pretreatment with the 5-HT2 receptor antagonist, ritanserin (1 mg/kg i.

Relationship between brain levels of 3-(3-hydroxyphenyl)-N-n-propylpiperidine HCl enantiomers and effects on locomotor activity in rats.

After s.c. administration of 3-(3-hydroxyphenyl)-N-n-propylpiperidine HCl (3-PPP) to rats, plasma and brain levels were monitored in relation to the amount of spontaneous locomotor activity.

Stimulation of 5-HT1A and 5-HT1B receptors in brain regions and its effects on male rat sexual behaviour.

In the present series of experiments we compared the effect of injecting serotonin (40 micrograms/cannula), the 5-HT1A agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) (5.0 micrograms/cannula), and the 5-HT1B/C agonist, trifluoromethyl-phenyl-piperazine (TFMPP) (1.0 micrograms/cannula), into the preoptic area, the nucleus accumbens and the nucleus raphe dorsalis.

Effects of sexual interactions on the in vivo rate of monoamine synthesis in forebrain regions of the male rat.

The effects of heterosexual interactions on the in vivo rate of regional brain monoamine synthesis were examined in the male rat. To this end, the animals were administered an inhibitor of cerebral aromatic L-amino acid decarboxylase, NSD-1015 (100 mg.kg-1 i.

Quinpirole--a 5-HT receptor antagonist?

The rate of brain monoamine synthesis was estimated in the rat by measuring the accumulation of dihydroxyphenylalanine (DOPA) and 5-hydroxytryptophan (5-HTP) following inhibition of cerebral aromatic amino acid decarboxylase by NSD-1015 (475 mumol/kg, i.p., 30 min before decapitation).