Brief exposure to a mild stressor enhances morphine-conditioned place preference in male rats

Ferguson, Adam R.; Patton, Brianne C.; Bopp, Anne C.; Meagher, Mary W.; Grau, James W.

doi:10.1007/s00213-004-1780-3

Cited by 13 publications

(8 citation statements)

References 38 publications

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“…Central sensitization is induced by peripheral nociceptive input (C-fiber activity resulting from injury or inflammation) and produces an increase in mechanical reactivity (allodynia) that has been linked to the development of neuropathic pain (Hohmann et al, 2005; Ma and Woolf, 1996; Yaksh et al, 1999; Young et al, 2007). Prior work has shown that central sensitization, and the induction of the learning deficit, are similarly affected by a host of pharmacological treatments (Baumbauer et al, 2007; Baumbauer et al, 2007b; Ferguson et al, 2004; Ferguson et al, 2006; Joynes and Grau, 2004; Joynes et al, 2004). Further, peripheral inflammation (from capsaicin or formalin) impairs subsequent learning (Ferguson et al, 2006; Hook et al, 2008).…”

Section: Discussionmentioning

confidence: 99%

Timing in the absence of supraspinal input I: Variable, but not fixed, spaced stimulation of the sciatic nerve undermines spinally-mediated instrumental learning

et al. 2008

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Rats with complete spinal transections are capable of acquiring a simple instrumentally trained response. If rats receive shock to one hindlimb when the limb is extended (controllable shock), the spinal cord will learn to hold the leg in a flexed position that minimizes shock exposure. If shock is delivered irrespective of leg position, subjects do not exhibit an increase in flexion duration and subsequently fail to learn when tested with controllable shock (learning deficit). Just 6 min of variable intermittent shock produces a learning deficit that lasts 24 hrs. Evidence suggests that the neural mechanisms underlying the learning deficit may be related to those involved in other instances of spinal plasticity (e.g., wind-up, long-term potentiation). The present paper begins to explore these relations by demonstrating that direct stimulation of the sciatic nerve also impairs instrumental learning. Six minutes of electrical stimulation (mono- or biphasic direct current [DC]) of the sciatic nerve in spinally transected rats produced a voltage-dependent learning deficit that persisted for 24 hr (Experiments 1–2) and was dependent on C-fiber activation (Experiment 7). Exposure to continuous stimulation did not produce a deficit, but intermittent burst or single pulse (as short as 0.1 ms) stimulation (delivered at a frequency of 0.5 Hz) did, irrespective of the pattern (fixed or variable) of stimulus delivery (Experiments 3–6, 8). When the duration of stimulation was extended from 6 to 30 min, a surprising result emerged; shocks applied in a random (variable) fashion impaired subsequent learning whereas shocks given in a regular pattern (fixed spacing) did not (Experiments 9–10). The results imply that spinal neurons are sensitive to temporal relations and that stimulation at regular intervals can have a restorative effect.

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Section: Discussionmentioning

confidence: 99%

Timing in the absence of supraspinal input I: Variable, but not fixed, spaced stimulation of the sciatic nerve undermines spinally-mediated instrumental learning

et al. 2008

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“…Therefore, it may be the case that early life pain could also predispose individuals to drug addiction later in life. In support of this notion, it has been shown that rats subjected to somatic injury (spinal cord contusion) (Woller et al 2012) or electrical pain (shock) (Ferguson et al 2004) exhibited greater conditioned place preference in response to morphine than controls. However, inflammatory pain (adjuvant-induced arthritis) (Lyness et al 1989) and neuropathic pain (L5 and L6 spinal nerve ligation) (Martin and Saleeby 2007) each blunted the apparent reinforcing effects of morphine in rats.…”

Section: Introductionmentioning

confidence: 93%

Predisposing effects of neonatal visceral pain on abuse-related effects of morphine in adult male Sprague Dawley rats

2014

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Rationale Adverse early life experiences are risk factors for drug abuse and addiction. Changes in brain opioid systems have been demonstrated in response to neonatal visceral pain (NVP), but the impact of these changes on abuse-related effects of morphine are unknown. The NVP procedure used models chronic visceral hyperalgesia persisting across development. Objectives Intravenous self-administration, drug discrimination, and locomotor activity were used to compare the abuse-related effects of morphine in NVP and control rats. Methods Rats self-administered 0.3 mg/kg/inj morphine under an FR1 schedule, and dose–effect functions for morphine were then established. Separate rats were trained to discriminate 3.2 mg/kg morphine from saline under an FR20 schedule, and morphine dose–effect functions were then determined in the absence and presence of 0.1 mg/kg naltrexone. A third group of rats was tested with a range of morphine doses in an assay of locomotor activity, then injected daily with 10 mg/kg morphine to assess locomotor sensitization. Results NVP rats self-administered more morphine than controls at reinforcing doses. Discriminative stimulus effects of morphine were similar between groups, but in the presence of naltrexone, the ED50 for morphine was more than 12× greater in control rats than in NVP animals. Morphine did not stimulate locomotor activity at any tested dose in NVP rats, although significant effects were observed in controls. Finally, significant locomotor sensitization was observed only in NVP rats. Conclusions NVP-induced changes in brain opioid systems have persistent pharmacological consequences into adulthood and may increase sensitivity to abuse-related effects of opioids across development.

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“…(2002) showed that if rats receive predictable (signaled) electrical footshocks in one compartment and unpredictable (non‐signaled) shocks in the other compartment of a shuttle box, they will develop a conditioned preference for the compartment that was paired with the predictable shocks. Moderate electrical tail shock stress prior to a place conditioning session produced CPA (Ferguson et al . 2004).…”

Section: Studies Using Systemic Drug Treatmentsmentioning

confidence: 99%

“…Exposure to moderate tail shock stress prior to conditioning enhanced the CPP effects of morphine (5 mg/kg sc, but not 0.2 and 1 mg/kg sc) (Ferguson et al . 2004).…”

Section: Studies Using Systemic Drug Treatmentsmentioning

confidence: 99%

REVIEW ON CPP: Measuring reward with the conditioned place preference (CPP) paradigm: update of the last decade

2007

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Conditioned place preference (CPP) continues to be one of the most popular models to study the motivational effects of drugs and non-drug treatments in experimental animals. This is obvious from a steady year-to-year increase in the number of publications reporting the use this model. Since the compilation of the preceding review in 1998, more than 1000 new studies using place conditioning have been published, and the aim of the present review is to provide an overview of these recent publications. There are a number of trends and developments that are obvious in the literature of the last decade. First, as more and more knockout and transgenic animals become available, place conditioning is increasingly used to assess the motivational effects of drugs or non-drug rewards in genetically modified animals. Second, there is a still small but growing literature on the use of place conditioning to study the motivational aspects of pain, a field of pre-clinical research that has so far received little attention, because of the lack of appropriate animal models. Third, place conditioning continues to be widely used to study tolerance and sensitization to the rewarding effects of drugs induced by pre-treatment regimens. Fourth, extinction/reinstatement procedures in place conditioning are becoming increasingly popular. This interesting approach is thought to model certain aspects of relapse to addictive behavior and has previously almost exclusively been studied in drug self-administration paradigms. It has now also become established in the place conditioning literature and provides an additional and technically easy approach to this important phenomenon. The enormous number of studies to be covered in this review prevented in-depth discussion of many methodological, pharmacological or neurobiological aspects; to a large extent, the presentation of data had to be limited to a short and condensed summary of the most relevant findings.

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Brief exposure to a mild stressor enhances morphine-conditioned place preference in male rats

Abstract: These results indicate that the affective state produced by moderate shock has a negative valence that is sufficient to support a conditioned place aversion. This state is associated with a general sensitization that enhances processing of appetitive US.

Cited by 13 publications

References 38 publications

Timing in the absence of supraspinal input I: Variable, but not fixed, spaced stimulation of the sciatic nerve undermines spinally-mediated instrumental learning

Timing in the absence of supraspinal input I: Variable, but not fixed, spaced stimulation of the sciatic nerve undermines spinally-mediated instrumental learning

Predisposing effects of neonatal visceral pain on abuse-related effects of morphine in adult male Sprague Dawley rats

REVIEW ON CPP: Measuring reward with the conditioned place preference (CPP) paradigm: update of the last decade

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