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Results for “SELF STIMULATION”

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At least 235 records · Page 13Linked to original sources

PubMed1985

Long-term changes in self-stimulation threshold by repeated morphine and naloxone treatment.

To analyse the interaction between endogenous opioid systems and brain reward, the influence of repeated treatment for 3 weeks with morphine and the opioid antagonist naloxone was investigated in rats with self-stimulation electrodes in the ventral tegmental area. Changes in threshold of self-stimulation determined by a response rate insensitive two lever method were considered as changes in reward. Morphine induced a temporary decrease of the response rate which lasted 3 days, and decreased the threshold for self-stimulation. The effect on threshold remained present till morphine treatment was discontinued, indicating that tolerance does not develop to this effect of morphine. Repeated naloxone treatment gradually increased the threshold for self-stimulation. This effect persisted after discontinuation of naloxone treatment. It is concluded that blockade of opioid receptors induces long term changes in the setpoint of self-stimulation reward.

Animals↗

PubMed1985

Pontine and mesencephalic substrates of self-stimulation.

Single or twin, moveable monopolar stimulating electrodes were implanted in male adult rats in order to map the medial pons and mesencephalon for self-stimulation behaviour. The electrodes were implanted 6 mm below the surface of the skull and subsequently moved down by steps of 0.13 or 0.16 mm. Each bar press in a Skinner box delivered a train (0.4 s in duration) of cathodal rectangular pulses of fixed intensity (200 microA) and width (0.1 ms). Self-stimulation was recorded from zero to the maximum performance by varying the number of pulses per stimulating train. The rewarding efficacy of the stimulation at each electrode location was inferred from determination of the pulse period corresponding to the threshold and half-maximal performance. Out of 361 mesencephalic and pontine sites sampled, 289 supported self-stimulation. Within the metencephalon, the study revealed a continuous band of positive sites, extending over a dorso-ventral distance of 4 mm, between the floor of the aqueduct and the pontine nuclei. Hence, all electrode locations in the central grey, dorsal raphe and median raphe supported self-stimulation. Within the mesencephalon, the positive band was restricted between the floor of the central grey and the middle part of the interpeduncular nucleus. At the rostral mesencephalon, it shifted laterally towards the substantia nigra. The overlap between the self-stimulation sites and some of the best known ascending and descending pathways is discussed.

Animals↗

PubMed1986

Effects of ACTH and related peptides on medial septal self-stimulation.

The effects of ACTH1-24, ACTH4-10, the ACTH4-9 analog Org 2766 and [D-Phe7] ACTH4-10 on medial septal self-stimulation were determined in the rat following intracerebroventricular (ICV) injections. Self-stimulation rates were increased by 0.01-10 micrograms ACTH1-24 or 0.1-10 micrograms ACTH4-10, but not by Org 2766 or [D-Phe7] ACTH4-10. A dose of 1 microgram ACTH1-24 ICV did not affect open field behaviour. Subcutaneous administration of 1 microgram ACTH1-24 did not influence self-stimulation in the septum. Thus, the ACTH1-24 effect appears to be a central effect and provides evidence for an influence of ACTH containing pathways on structures involved in maintaining self-stimulation behavior. A possible role of opiate receptors and dopaminergic neurons in this effect of ACTH1-24 is also discussed.

Adrenocorticotropic Hormone↗

PubMed1989

[Cyclic analogs of ACTH fragments in self-stimulation and grooming behavior in rabbits].

In present study new cyclic fragments of ACTH EHFRWGKPVG--NH2 and KHFRWG--NH2 were investigated in organization of self-stimulation and grooming behaviour in rabbits. Intracerebroventricular injections of EHFRWGPVG--NH2 in doses of 0.1-2.5 g evoked significant increases of self-stimulation and in doses of 4-5 g suppressed self-stimulation in rabbits. The effect of other fragments KHFRWG--NH2 on self-stimulation was not statistically significant. Both fragments induced excessive grooming behaviour in rabbits. The effects of these fragments persisted of 48-72 hours.

Adrenocorticotropic Hormone↗

PubMed2004

Video reveals self-stimulation in infancy.

UNLABELLED: The medical literature on early childhood masturbation is sparse. Only 12 patients who presented with infantile self-stimulation under the age of 1 y are described. During the last 2 y, five girls under 1 y of age presented at our department with self-stimulating behaviour. The diagnosis of this behaviour was difficult, but could be made by watching a video of the attacks. Infantile self-stimulation is often misdiagnosed and unnecessary investigations and useless treatments are often prescribed. Video recording can be of great help to put forward the correct diagnosis. Masturbation is not so uncommon and treatment consists mostly in reassuring the parents. It can, however, be associated with behavioural problems. Few data are available on the clinical outcome of childhood masturbation, but most children seem to develop normally. CONCLUSION: Infantile self-stimulation should always be considered in the differential diagnosis of "strange episodes or attacks".

Diagnosis, Differential↗

PubMed1989

Interhemispheric relationship between lateral hypothalamic self-stimulation and the region of the nucleus tegmenti pedunculo-pontinus.

Electrical self-stimulation in the lateral hypothalamus was recorded in both hemispheres of 20 rats before and after making a lesion either by unilateral radiofrequency stimulation or by injection of N-methyl-D,L-aspartate into the region of the peduncular-pontine nucleus. For the animals which received the radiofrequency lesion, a rate-intensity function was established for 3 stimulation intensities 3 days before and 5 days after the lesion. For the animals in which N-methyl-D,L-aspartate was injected, a reinforcement threshold was measured 3 days before and after the lesion using a psychophysical method-of-limits procedure. With the rate-intensity procedure a decrease in the rate of self-stimulation was observed at the highest stimulation intensity through the electrode situated contralateral to the side of the lesion. Similarly, with the reinforcement threshold method, a significant increase in threshold was found from the electrode placed in the hemisphere contralateral but not ipsilateral to the site of the lesion. These data suggest an involvement of primarily crossed pathways coursing to or from the peduncular-pontine nucleus as being involved in the control of lateral hypothalamic self-stimulation.

Animals↗

PubMedDate not supplied

[Direct current self stimulation in rats].

In experiments on 16 male albino rats a phenomenon of self-stimulation of the hypothalamic structures has been produced by a DC anode and cathode, with 20 to 100 microamperes intensity. DC self-stimulation consists in regular succession of approaching the pedal, staying on the pedal and leaving it, i. e. a succession of states of motivational drive, reinforcement and avoidance. In a number of cases the conditioned reflex of self-stimulation is not extinguished for two to three days after switching off the current.

Animals↗

PubMed1979

Alteration of cyclic nucleotide levels in brain following intracranial self-stimulation in the rat.

In a first experiment, 14 rats were implanted with an electrode in the ventral tegmental area and trained to self-stimulate. On the experimental day only half of the rats were allowed to self-stimulate for about one hour. All rats were then sacrificed by immersion in liquid nitrogen. Seven brain regions were dissected and assayed for the endogenous concentration of cyclic nucleotides. Self-stimulation induced significant changes in striatum and hippocampus. However, a subsequent experiment showed that the same pattern of changes in the striatum can be produced by motor activity. On the other hand, changes in the hippocampus were specific to the self-stimulation group suggesting that this structure is associated with the brain reward system.

Animals↗

PubMedDate not supplied

d-Fenfluramine and self-stimulation: loss of inhibitory effect in underweight rats.

The question addressed is whether or not physiological factors associated with body weight, are necessary for serotonergic inhibition of feeding reward. Six rats received the serotonergic drug d-fenfluramine (d-FEN 1.5 and 2.5 mg/kg IP) while they electrically self-stimulated a perifornical lateral hypothalamic (PfLH) site that would induce feeding. As a control, self-stimulation was alternated with stimulation-escape. Both were measured at normal body weight, then at 80% body weight, then normal weight again. Three results were significant. 1) d-FEN markedly suppressed self-stimulation at normal body weight. 2) Self-stimulation rate increased when the animals were put on a diet that reduced body weight to 80% of normal. 3) At this low body weight, d-FEN no longer had any effect on self-stimulation. The results suggest that some correlate of normal food intake or body weight is necessary for serotonergic inhibition of the PfLH feeding-reward system. Possible explanations for fenfluramine's loss of effect at low weight are discussed.

Analysis of Variance↗

PubMed1989

Increased dopamine and serotonin metabolism in rat nucleus accumbens produced by intracranial self-stimulation of medial forebrain bundle as measured by in vivo microdialysis.

In the present study, we have used a newly developed microdialysis system to perfuse the nucleus accumbens (NAC) of conscious rats during spontaneous intracranial self-stimulation of the medial forebrain bundle (MFB). Chromatographic (HPLC-ECD) analysis of the perfusates showed that dopamine (DA) release increased, but with an unstable pattern during the actual period of self-stimulation. On the other hand, the main DA metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, and a serotonin metabolite 5-hydroxyindoleacetic acid, were all markedly enhanced by self-stimulation, but with different time courses. These findings indicate that self-stimulation of the MFB in rats induces increases in both DA and serotonin activities in the NAC. Such changes may be involved in mediating self-stimulation of the MFB.

3,4-Dihydroxyphenylacetic Acid↗

PubMedDate not supplied

[A comparison of the self-stimulation reaction and of conditioned place preference with fenamine administration in rats].

The reinforcing properties of different doses of amphetamine (1 and 5 mg/kg) were examined using two variants of self-stimulation reaction (in the Skinner box and locomotor self-stimulation in a shuttle box) and place preference test. Amphetamine in dose of 1 mg/kg increased the frequency of self-stimulation in the Skinner box and prolonged the time of rat staying in active zone of a shuttle box to a greater degree than 5 mg/kg of the drug. On the contrary, the aversive phase of self-stimulation, determined by a coefficient of "disagreement", grew higher after 5 mg/kg amphetamine than following 1 mg/kg. The study of effects by place preference test revealed the other regularity: the most positive reinforcing properties possessed the drug in a dose of 5 mg/kg. Thus, there are dissociation between the two doses of amphetamine (1 and 5 mg/kg) in their action on different physiological conditioned responses. The mechanisms of this dissociation are discussed.

Amphetamine↗

PubMed1999

Differential sensitivity of the caudal and rostral nucleus accumbens to the rewarding effects of a H1-histaminergic receptor blocker as measured with place-preference and self-stimulation behavior.

A recent series of studies in rats has demonstrated positively reinforcing and memory enhancing effects following lesions of the nucleus tuberomammillaris, which is the only known source of neuronal histamine. The aim of the present experiments was to assess whether inhibition of histaminergic neurotransmission in the ventral striatum has positively reinforcing effects. In Experiment 1 rats with chronically-implanted cannulae were injected with the H1 receptor blocker d-( + )-chlorpheniramine at doses of 0.1, 1.0 and 10.0 microg into the rostral or caudal parts of the nucleus accumbens, a brain region known to be involved in reward-related processes. Immediately after the treatment the animals were placed into one of four restricted quadrants of a circular open field (closed corral) for a single conditioning trial. During the drug-free test for conditioned place preference, when a choice among the four quadrants was provided, those rats injected with 10.0 microg chlorpheniramine in the caudal nucleus accumbens spent more time in the treatment corral, indicative of a positively rewarding drug action. In Experiment 2 the question was posed whether injection of chlorpheniramine into the nucleus accumbens influences electrical self-stimulation of the lateral hypothalamus. For this purpose rats were chronically implanted with two bipolar electrodes aimed at the lateral-hypothalami and with two additional guide cannulae aimed either at the rostral or caudal nucleus accumbens. After having established reliable self-stimulation behavior at one of the two electrode sites the animals were allowed to self-stimulate for one hour (baseline). Then they were unilaterally injected with 10.0 microg chlorpheniramine or vehicle and allowed to self-stimulate for another hour (test). On the next day the same procedure took place, except for the difference that the animals received an injection aimed at the hemisphere not treated so far. Animals treated with chlorpheniramine in the caudal and in the rostral nucleus accumbens displayed higher rates of ipsihemispheric self-stimulation behavior. Moreover, the animals treated with the H1 receptor blocker in the caudal nucleus accumbens displayed higher rates of ipsihemispheric self-stimulation than those having received an injection in the rostral pole. Upon completion of this part of the experiment all animals received an additional intraperitoneal treatment with chlorpheniramine (20 mg/kg) or vehicle, respectively, and were tested in the same way described above. This treatment also resulted in an amplification of intracranial self-stimulation behavior. These results support the hypothesis that histaminergic neurotransmission is involved in the inhibitory control of a central system subserving reward-related processes. The present data also further highlight the nucleus accumbens as functionally heterogenous along its rostrocaudal axis, with the caudal-shell subregion being more sensitive to antihistaminic induced reward than the rostral entity.

Animals↗

PubMedDate not supplied

Analysis of hypothalamic self-stimulation with stimulation of fixed duration.

Correlation between the frequency of bar pressing and the frequency of hypothalamic self-stimulation of fixed duration was studied in cats during changes in strength of the stimulating current. Strong direct correlation was found between the frequency of bar pressing and the frequency of self-stimulation, whereas strong negative correlation was found between the frequency of pressing and the animal's "work effectiveness." It is suggested that the strongest motivation arises in the presence of an optimal strength of self-stimulation, giving rise to maximal frequency of bar pressing.

Animals↗

PubMed1983

Opiate-receptor blockade reduces voluntary running but not self-stimulation in hamsters.

Naltrexone HCl, a long-acting opiate receptor blocker was administered to female hamsters at two doses, 10 and 20 mg/kg, IP prior to 12 hr of nocturnal running or every 12 hr during access to hypothalamic self-stimulation to determine whether endogenous opiates played a role in either of these two motivated behaviors. Naltrexone suppressed total running activity and speed, and caused an increase in pause time but did not affect the rate of hypothalamic self-stimulation. Furthermore, weight gain was unaffected by four weeks of self-stimulation but was accelerated during two weeks of voluntary running. Thus stimulation of endogenous opiate receptors helps support high levels of voluntary running but is not involved in initiation of running or in maintenance of intracranial self-stimulation in female hamsters. Furthermore, the association of opiate receptor stimulation and increased somatic growth with voluntary running but not with self-stimulation suggests a possible facilitatory role for endogenous opiates in acceleration of growth by exercise.

Animals↗

PubMedDate not supplied

Influence of intracerebroventricularly and intracisternally administered vasopressin on the hypothalamic self-stimulation rate of the rat.

Lysine-vasopressin (LVP) at different concentrations (2 ng, 200 pg) was injected into the lateral ventricle and cisterna magna. The effect on hypothalamic self-stimulation was studied in rats. LVP (2 ng) decreased the self-stimulation rate after intracerebroventricular and cisternal application. Injection of 200 pg LVP diminished the self-stimulation rate after cisternal administration only. The findings suggest that the site of peptide administration is of decisive importance to vasopressin-induced effects. Both biochemical factors and the interaction between behaviour and vegetative nervous system should be taken into consideration when interpreting changes in self-stimulation as induced by vasopressin applied to the CSF space.

Animals↗

PubMed2000

In vivo voltammetry with removable carbon fibre electrodes in freely-moving mice: dopamine release during intracranial self-stimulation.

The advantages of in vivo voltammetry at carbon fibre electrodes cannot be fully realised without the registration of neurotransmitter release in freely moving animals. Here we describe an approach to record electrically evoked dopamine release in freely-moving mice. A description of a simple in-house made micromanipulator (0.4 g) and preamplifier (0.6 g) is given. This system was used to record electrochemical signal in the nucleus accumbens four to eight times during 2 weeks following intracranial self-stimulation (ICSS) of the median forebrain bundle. High-speed chronoamperometry was found to be the best choice for recording. The most efficient parameters of electrical stimulation for training and self-stimulation (50 Hz, 0.2 s, 60 microA) were insufficient to induce a measurable voltammetric signal. Increasing the strength of stimulation (0.5 s, 160 microA) significantly decreased the rate of self-stimulation and allowed the registration of separate peaks of dopamine overflow on each stimulation and a tonic increase of electrochemical signal following higher rates of ICSS. Due to exhaustion of the readily releasable dopamine pool, the length of recording the electrochemical signal depended on the rate of self-stimulation. A fixed ratio schedule of ICSS decreased the rate of electrical stimulation and permitted the maintenance of stable peaks of dopamine overflow at a high rate of nose-poking.

Animals↗

PubMed1985

Lateralized decrease in self-stimulation induced by haloperidol in rats with unilateral 6-hydroxydopamine lesions.

Rats with bilateral hypothalamic electrode placements which generated similar self-stimulation rate-intensity functions were subjected to unilateral injections of 6-hydroxydopamine (6-OHDA) into A9 and A10 areas. Following 12 weeks of postoperative recovery which was bilaterally symmetrical the rats were administered 0.1 mg/kg haloperidol. In sham- and vehicle-injected control rats the haloperidol produced bilaterally symmetrical decreases in self-stimulation. In the rats with 6-OHDA lesions the haloperidol effect was asymmetric with a much greater decrease in self-stimulation evident for electrode placements in the dopamine deficient hemisphere than for electrodes in the non-lesion hemisphere. Biochemical evaluation of the lesions indicated that dopamine was severely depleted in limbic and striatal forebrain areas. The combined use of a lesion with a pharmacological blockade of a neurotransmitter system appears to be an effective technique to distinguish reward versus performance effects of the transmitter on self-stimulation.

Animals↗

PubMed1991

Re-evaluation of the role of dopamine in intracranial self-stimulation using in vivo microdialysis.

Rats were implanted with an electrode-microdialysis assembly in order to test the hypothesis that the reward signal elicited by medial forebrain bundle stimulation is relayed by the meso-accumbens dopamine cells. We first obtained the strength-duration function of self-stimulation, that is, a family of behaviorally equivalent stimuli (pulse intensity and pulse duration pairs yielding a constant self-stimulation rate). We then collected the self-stimulation-bound intra-accumbens dopamine for several pairs of intensity and duration, selected from within the strength-duration function. Our reasoning was that if the reward signal travels along the meso-accumbens dopaminergic neurons, the release of dopamine should not depend on the stimulus parameters because behaviorally equivalent stimuli should produce a constant output in all neural stages carrying the reward signal. The results showed that short duration/high intensity pulses induced considerably larger increases in dopamine levels than long duration/low intensity pulses, despite the fact that these stimuli maintained a constant self-stimulation rate. Among the interpretations envisaged, the most parsimonious one seems to be that the MFB rewarding signal is not relayed exclusively by meso-accumbens dopaminergic cells and that the latter may play a permissive-facilitator role at some transmission stage of the reward signal.

Animals↗