Long-term effects of short and long periods of maternal separation on brain opioid peptide levels in male Wistar rats

Ploj, Karolina; Roman, Erika; Nylander, Ingrid

doi:10.1016/s0143-4179(03)00043-x

Cited by 65 publications

(57 citation statements)

References 47 publications

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“…of D rats. This is in contrast to the lack of changes of opioid peptide levels in the striatum of separated rats published recently (Ploj et al, 2003b). However, the discrepancies could be explained by the differences in the methodology used (the protocol of separation, the peptides measured, cerebral regions vs subregions studied, global vs extracellular levels of peptide measured).…”

Section: Discussioncontrasting

confidence: 68%

Maternal Deprivation Increases Vulnerability to Morphine Dependence and Disturbs the Enkephalinergic System in Adulthood

Vazquez

Penit-Soria²,

Durand³

et al. 2005

J. Neurosci.

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Maternal deprivation can trigger long-lasting molecular and cellular modifications in brain functions and might facilitate the appearance of pathogenic behaviors. This study focuses on the vulnerability to develop morphine dependence in adult rats that were separated from their mother and littermates for 3 h per day for 14 d after birth and examines the adaptive changes in the enkephalinergic pathways. Place-preference conditioning was observed with 2 mg/kg morphine in deprived rats, whereas 5 mg/kg morphine was necessary to induce conditioning in nondeprived animals. A prolonged morphine conditioning was shown in deprived rats. A strong increase in oral morphine self-administration behavior and preference was observed in deprived rats. Only a very slight increase in preference for sucrose solution, a more ethological reinforcer known to interact with the opioid system, was shown in deprived rats. These results indicate that this postnatal environment change leads to a hypersensitivity to the reinforcing properties of morphine and to the development of morphine dependence. A significant decrease in preproenkephalin mRNA expression was observed in the nucleus accumbens and the caudate-putamen nucleus of deprived rats. The basal extracellular levels of the Met-enkephalin-like immunoreactivity in the nucleus accumbens were significantly lower in deprived rats when compared with nondeprived animals, whereas no change in -opioid receptor binding occurred. These results strongly support that maternal deprivation leads to a basal hypoactivity of the enkephalinergic system and hypersensitivity to morphine effects.Together, our results suggest that maternal deprivation in pups likely represents a risk factor for morphine dependence in adult rats.

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Section: Discussioncontrasting

confidence: 68%

Maternal Deprivation Increases Vulnerability to Morphine Dependence and Disturbs the Enkephalinergic System in Adulthood

Vazquez

Penit-Soria²,

Durand³

et al. 2005

J. Neurosci.

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“…Met-enkephalin and preproenkephalin mRNA levels decrease in the nucleus accumbens (Vazquez et al, 2005b), and this change is coupled with a decrease in enkephalin metabolic enzymes (Irazusta et al, 1999) and d-opioid receptors (Ploj et al, 2003b) in amygdala. In contrast, met-enkephlinArg6-Phe7 (MEAP), a marker of proenkephalin, is increased in the prefrontal cortex, nucleus accumbens, hypothalamus, and periaqueductal gray (Ploj et al, 2001(Ploj et al, , 2003b. After a history of alcohol self-administration, MEAP is decreased in medial prefrontal cortex and periaqueductal gray area, although increases in MEAP are evident in the striatum and hypothalamus (Gustafsson et al, 2007).…”

Section: B Social Influencesmentioning

confidence: 99%

“…Dynorphin B, a marker of prodynorphin, is increased in several regions, with more widespread effects observed with brief maternal separation (i.e., pituitary gland, striatum, periaqueductal gray, hippocampus, substantia nigra, medulla) and more restricted effects observed with prolonged maternal separation (Ploj et al, 1999(Ploj et al, , 2003b. Findings in the hypothalamus have been mixed, likely the result of sex differences, as maternally separated females exhibit a decrease in dynorphin B , whereas maternally separated males exhibit an increase in dynorphin B (Ploj et al, 1999(Ploj et al, , 2003b. Additionally, with brief maternal separation, dynorphin B is decreased in the frontal cortex and amygdala (Ploj et al, 1999(Ploj et al, , 2001(Ploj et al, , 2003b.…”

Section: B Social Influencesmentioning

confidence: 99%

“…Findings in the hypothalamus have been mixed, likely the result of sex differences, as maternally separated females exhibit a decrease in dynorphin B , whereas maternally separated males exhibit an increase in dynorphin B (Ploj et al, 1999(Ploj et al, , 2003b. Additionally, with brief maternal separation, dynorphin B is decreased in the frontal cortex and amygdala (Ploj et al, 1999(Ploj et al, , 2001(Ploj et al, , 2003b. However, opposite effects are observed in animals after alcohol selfadministration.…”

Section: B Social Influencesmentioning

confidence: 99%

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Individual Differences and Social Influences on the Neurobehavioral Pharmacology of Abused Drugs

2013

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“…There is some evidence that early adverse life events may affect the brain serotonergic receptor system (Vazquez, Eskandari, Zimmer, Levine, & Lopez, 2002), the mesolimbic dopamine transporter expression (Meaney et al, 2002) and development of the GABAA and central benzodiazepine receptors (Caldji et al, 2000). Moreover, recent studies have indicated that early manipulation also affects the endogenous opioid system, dopamine receptors, and the nociceptin/orphanin FQ system (Ploj, Roman, & Nylander, 2002, 2003bPloj et al, 2003a). The endogenous opioid system is activated by different kinds of stressors and is suggested to play an important role in brain reward pathways implicated in drug abuse (Koob, 1992).…”

Section: Introductionmentioning

confidence: 99%

Maternal separation alters maternal care, but has minor effects on behavior and brain opioid peptides in adult offspring

Marmendal

Roman

Eriksson

et al. 2004

Developmental Psychobiology

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The aim of the study was to investigate the effect of repeated maternal separation (MS; 4 hr per day) during postnatal Days 1 to 15 on emotionality and voluntary ethanol intake in adult male and female Wistar rat offspring relative to controls exposed to a brief (5-min) daily handling procedure. Brain immunoreactive opioid peptide levels and plasma levels of corticosterone also were measured. There were mainly no alterations in any of the tested behaviors (i.e., fleeing and freezing responses, exploratory behavior, spontaneous and amphetamine-induced locomotor activity and competitive behavior), ethanol intake, or immunoreactive opioid peptide levels in MS offspring, either in males or females, compared to their respective controls nor were there any differences in plasma corticosterone between groups. In addition, the dams' retrieval behavior of the pups also was studied, showing that MS dams spent more time in the nest with the pups after the 4-hr separation period compared to control dams. With respect to the used protocol of the MS procedure in the present study, our results do not provide support for the suggestion that this procedure is a relevant model for studying development of psychopathology and vulnerability to drug abuse.

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Long-term effects of short and long periods of maternal separation on brain opioid peptide levels in male Wistar rats

Cited by 65 publications

References 47 publications

Maternal Deprivation Increases Vulnerability to Morphine Dependence and Disturbs the Enkephalinergic System in Adulthood

Maternal Deprivation Increases Vulnerability to Morphine Dependence and Disturbs the Enkephalinergic System in Adulthood

Individual Differences and Social Influences on the Neurobehavioral Pharmacology of Abused Drugs

Maternal separation alters maternal care, but has minor effects on behavior and brain opioid peptides in adult offspring

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