The first suckling episode in the rat: The role of endogenous activity at mu and kappa opioid receptors

Petrov, Evgeniy S.; Smotherman, William P.

doi:10.1002/1098-2302(200011)37:3<129::aid-dev2>3.0.co;2-p

Cited by 11 publications

(9 citation statements)

References 63 publications

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“…Of course, none of the studies of newborn human or lamb olfactory preferences specifically implicate neural systems that may mediate infant responses. Therefore, the present study may aid in filling this gap by implicating a common mechanism underlying the behavioral effects of milk and AF in fetal and newborn rats: both fluids appear to activate the kappa subclass of opioid receptors in fetuses (milk: Smotherman & Robinson, 1992c; AF: Korthank & Robinson, 1998) and newborns (milk: Petrov et al, 2000, this study; AF: this study).…”

Section: Discussionmentioning

confidence: 77%

“…For example, the greater latency to respond to a thermal stimulus after oral exposure to milk was reversed when pups were pretreated with the nonspecific opioid antagonist naloxone (Blass et al, 1991). Direct injection of naloxone or a selective kappa opioid antagonist into the cerebral ventricles also caused newborn pups to show a greater latency to attach to a surrogate nipple that provided milk, and markedly reduced time on the nipple and milk intake (Petrov, Varlinskaya, & Smotherman, 1998; 2000). Diminished responses of fetal rats to a perioral stimulus after milk exposure also were prevented by blockade of the opioid system: both naloxone and the selective kappa antagonist nor-binaltorphimine (BNI) blocked the effect of milk and reinstated high levels of wiping in response to perioral stimulation in E20 rat fetuses (Smotherman & Robinson, 1992a, 1992c).…”

Section: Discussionmentioning

confidence: 99%

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Opioid mediation of amniotic fluid effects on chemosensory responsiveness in the neonatal rat

Méndez-Gallardo

Robinson

2010

Developmental Psychobiology

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The present study investigated if oral exposure to milk or amniotic fluid (AF) alters responsiveness to sensory stimulation in the neonatal rat, and whether these effects are mediated by the opioid system. Facial wiping evoked by intraoral lemon infusion was used as a measure of sensory responsiveness. Pups were tested in a supine posture, because they showed more paw-face strokes during facial wiping than pups tested prone (Experiment 1). Moreover, pups orally exposed to milk (Experiment 2) or AF (Experiment 3) showed a diminished wiping response to lemon compared to controls exposed to water. Blockade of opioid receptors with the non-selective antagonist naltrexone (Experiment 4) or the kappa antagonist nor-binaltorphimine (Experiment 5) reinstated higher levels of facial wiping after AF exposure. These findings confirm developmental continuity between fetal and neonatal behavioral responses to AF and the ability of AF to induce activity at kappa receptors of the endogenous opioid system.

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Section: Discussionmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Opioid mediation of amniotic fluid effects on chemosensory responsiveness in the neonatal rat

Méndez-Gallardo

Robinson

2010

Developmental Psychobiology

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“…Hence, it seems that activation of Kappa opioid receptors is not necessary for ethanol’s stimulating effects in rats near athe end of their second postnatal week. This conclusion has to be carefully considered since it has been reported that in adult rats, nor-binaltorphimine is not selective for kappa antagonism over mu opioid antagonism for 24 hours or more after administration (Metcalf & Coop, 2005), although some studies have shown selective effects on kappa receptors within an hour of the antagonist’s administration in newborn (Petrov, Varlinskaya & Smotherman, 2000) or adult animals (Campbell, Taylor & Tizabi, 2007). The lack of effect of the kappa antagonists on locomotion and intake tests in the present study may be due to the fact that nor-binaltorphimine was administered 30 minutes before testing, a postadministration time that might be too soon after administration for an effect upon mu and kappa receptors.…”

Section: Resultsmentioning

confidence: 99%

Differential role of mu, delta and kappa opioid receptors in ethanol-mediated locomotor activation and ethanol intake in preweanling rats

Arias¹,

Molina²,

Spear³

2010

Physiology & Behavior

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The opioid system modulates ethanol intake and reinforcement in adult and preweanling rodents. While adult heterogeneous rats normally do not show ethanol-mediated locomotor stimulation, preweanling rats show it quite clearly. We recently observed that naloxone, a non-specific opioid antagonist, attenuated ethanol-induced locomotor activation in preweanling rats. In the present study we tested the role of specific opioid receptors (mu, delta and kappa) in ethanol-mediated locomotor stimulation and ethanol intake. In Experiment 1 13-day-old rats received naloxonazine (mu antagonist: 0, 7.5 or 15 mg/kg), naltrindole (delta antagonist: 0, 2 or 4 mg/kg) or nor-binaltorphimine (kappa antagonist: 0, 2, 4 or 8 mg/kg) before an intragastric administration of ethanol (0 or 2.5 g/ kg), and subsequent locomotor activity assessment. In Experiment 2, the same opioid antagonists were administered on postnatal days 13 and 14 before consumption of ethanol (6%), saccharin (0.05%) or distilled water. In Experiment 1 only naloxonazine reduced ethanol-mediated locomotor stimulation. None of the opioid antagonists affected locomotor activity in water controls. In Experiment 2 naloxonazine and naltrindole suppressed ingestion of all the solutions tested. Similar to what has been reported in adult rodents, mu-opioid receptors seem to modulate ethanol-activating effects during early ontogeny. Hence, there seems to be a partial overlap of neurochemical mechanisms involved in the rewarding and stimulating effects of ethanol in preweanling rats. Mu receptor antagonists reduced both ethanol-induced activity and ethanol intake, but it is unclear whether the latter effect is specific to ethanol or only a reflection of an effect on consummatory behavior generally, since mu and delta receptor antagonists also suppressed ingestion of water and sacccharin.

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“…Rats at P7 were randomly divided into an MeCP2 shRNA group and a control shRNA group. A mixture containing 1 lg plasmids in 9 lL of 0.9% (w/v) sterile sodium chloride solution and 1 lL of Lipofectamine 2000 (Invitrogen) was injected into the cisterna magna as previously described [27]. Briefly, a 26-G needle of a 1-mL syringe was bent to a 45°angle 4 mm from the tip.…”

Section: Plasmid Injectionmentioning

confidence: 99%

Expression of Phospho-MeCP2s in the Developing Rat Brain and Function of Postnatal MeCP2 in Cerebellar Neural Cell Development

Liu

Sun

2016

Neurosci. Bull.

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Abnormal expression and dysfunction of methyl-CpG binding protein 2 (MeCP2) cause Rett syndrome (RTT). The diverse phosphorylation modifications modulate MeCP2 function in neural cells. Using western blot and immunohistochemistry, we examined the expression patterns of MeCP2 and three phospho-MeCP2s (pMeCP2s) in the developing rat brain. The expression of MeCP2 and phospho-S80 (pS80) MeCP2 increased while pS421 MeCP2 and pS292 MeCP2 decreased with brain maturation. In contrast to the nuclear localization of MeCP2 and pS80 MeCP2, pS421 MeCP2 and pS292 MeCP2 were mainly expressed in the cytoplasmic compartment. Apart from their distribution in neurons, they were also detected at a low level in astrocytes. Postnatallyinitiated MeCP2 deficiency affected cerebellar neural cell development, as determined by the abnormal expression of GFAP, DCX, Tuj1, MAP-2, and calbindin-D28k. Together, these results demonstrate that MeCP2 and diverse pMeCP2s have distinct features of spatio-temporal expression in the rat brain, and that the precise levels of MeCP2 in the postnatal period are vital to cerebellar neural cell development.

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The first suckling episode in the rat: The role of endogenous activity at mu and kappa opioid receptors

Cited by 11 publications

References 63 publications

Opioid mediation of amniotic fluid effects on chemosensory responsiveness in the neonatal rat

Opioid mediation of amniotic fluid effects on chemosensory responsiveness in the neonatal rat

Differential role of mu, delta and kappa opioid receptors in ethanol-mediated locomotor activation and ethanol intake in preweanling rats

Expression of Phospho-MeCP2s in the Developing Rat Brain and Function of Postnatal MeCP2 in Cerebellar Neural Cell Development

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