Naloxone suppresses intake of highly preferred saccharin solutions in food deprived and sated rats

Lynch, Wesley C.; Libby, L. S.

doi:10.1016/0024-3205(83)90675-6

Cited by 99 publications

(39 citation statements)

References 21 publications

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“…The SC dosages of naloxone used in this study were chosen on the basis of a previous study (Miller and Baum 1987) which showed that 1 or 5 mg/kg could reduce the expression of sexual behavior in males which had been castrated 2 weeks previously. These doses of naloxone are also within the range used by numerous other investigators interested in the role of opioid peptides in the regulation of several different consumatory behaviors (Lynch and Libby 1983;Kirkham and Blundell 1987) as well as brain electrical self-stimulation behavior (Belluzi and Stein 1977) in rats. The present study was designed so that males were first exposed to an oestrous female in an initial conditioning test given 9 days after castration, a time when their coital performance would be beginning to wane.…”

Section: Methodsmentioning

confidence: 94%

Naloxone disrupts the expression but not the acquisition by male rats of a conditioned place preference response for an oestrous female

1990

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Two experiments were conducted to investigate the possible role of endogenous opioid peptides in the regulation of masculine sexual reward. In experiment 1 sexually experienced male rats, which had recently been castrated or left gonadally intact, were allowed to mate with an oestrous female in an initially "non-preferred" chamber of a test apparatus. On alternate days these males were placed alone in the initially "preferred" chamber of the same apparatus. After eight such conditioning sessions both intact and castrated males had acquired a conditioned place preference (CPP) for the initially "non-preferred" chamber whereas control males, which were never given access to an oestrous female, showed no evidence of a significant shift in their preference for either chamber. Administration of the opioid receptor antagonist, naloxone (1 or 5 mg/kg, SC) prior to each conditioning session had no significant influence on the acquisition of a CPP for an oestrous female. By contrast, in experiment 2 naloxone treatment significantly attenuated the expression of a previously established CPP for an oestrous female in both gonadally intact and castrated males. The results suggest that opioid components of neural reward circuits are normally activated in the male rat by conditioned incentive stimuli, but not by the primary rewarding stimuli associated with access to and mating with an oestrous female.

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Section: Methodsmentioning

confidence: 94%

Naloxone disrupts the expression but not the acquisition by male rats of a conditioned place preference response for an oestrous female

1990

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“…A sim ilar increase in reward value would be expected to occur for the mother. Naloxone was hypothesized to reduce the motivation to stay close to the mother just as the antago nist reduces the reward value of other natural reinforcers [11,13,14,[29][30][31], These predictions may appear astonishing in light of earlier studies showing that opioids reduce social interac tion. However, most of these studies used animals at an age where opioids would no longer be important for moth er-offspring interaction according to our predictions [32][33][34][35][36].…”

Section: Introductionmentioning

confidence: 88%

“…The naloxone dose used here reduces the consumption of sweet solutions [29,42] and food [44], and efficiently blocks conditioned place preference produced by morphine [45]. It is, therefore, a dose known to diminish the reward value of several types of rewards.…”

Section: Methodsmentioning

confidence: 99%

Social Motivation in Recently Weaned Rats Is Modified by Opiates

Ågmo¹,

Barreau²,

Lemaire³

1997

Dev Neurosci

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An open field choice test was used to determine whether maternal deprivation enhanced the motivation to stay close to the mother. Pups could choose between the dam, 3 sisters and 3 unknown animals of the same age. In addition, an empty enclosure identical to those that contained the stimulus animals were present as a nonsocial choice. Rats that were separated from their mother at 20 days of age and tested about 13 h later were compared to animals that had stayed with the mother until just before the test. It was found that maternal separation increased the time spent close to the mother and reduced that spent close to strangers or an empty enclosure. In fact, weaned animals spent far more time close to the mother than they spent close to any other available choice. Moreover, the mean duration of visits to the mother was much increased during the latter half of the 60-min test. These data were interpreted as showing that the mother had rewarding properties, and that maternal deprivation increased her reward value. In further experiments, the role of opioids for this increase in reward value was evaluated. Morphine enhanced the time spent close to the mother, but only in animals that had been subjected to maternal deprivation for about 13 h. Naloxone had the opposite effect. These data show that the mother''s reward value is altered when the activity of opioid systems is modified. It is suggested that the mother acquires rewarding properties because of association with nutritive suckling-induced opioid release.

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“…Both of these mechanisms reduce the body's perception of pain similarly to addictive drugs, such as morphine and codeine [ 27 ] . In addition, manipulating opioid levels through the administration of either agonists such as morphine or antagonists such as naltrexone has a corresponding effect on the intake of sweet and other highly palatable foods, raising or lowering them, respectively [ 28 ] . A consumer's experience of the food (whether or not it is pleasant tasting) is implicated in the release of endorphins in the brain, and thus, the effects of chocolate in an individual's body can be increased or decreased by his or her pleasant experience of the food [ 21 ] .…”

Section: The Opioid Reward Systemmentioning

confidence: 99%