Neonatal tactile stimulation reverses the effect of neonatal isolation on open-field and anxiety-like behavior, and pain sensitivity in male and female adult Sprague–Dawley rats

Department of Psychiatry and Neurosciences, Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Sciences, Hiroshima University, Minami-ku, 734-8551 Hiroshima, Japan.
Behavioural Brain Research (Impact Factor: 3.03). 02/2008; 186(1):91-7. DOI: 10.1016/j.bbr.2007.07.039
Source: PubMed


It is well known that early life events induce long-lasting psychophysiological and psychobiological influences in later life. In rodent studies, environmental enrichment after weaning prevents the adulthood behavioral and emotional disturbances in response to early adversities. We compared the behavioral effect of neonatal isolation (NI) with the effect of NI accompanied by tactile stimulation (NTS) to determine whether NTS could reverse or prevent the effects of NI on the adulthood behavioral and emotional responses to environmental stimuli. In addition, we also examined the sex difference of the NTS effect. Measurements of body weights, an open-field locomotor test, an elevated plus maze test, a hot-plate test, and a contextual fear-conditioning test were performed on postnatal day 60. As compared with rats subjected to NI, rats subjected to NTS showed significantly higher activity and exploration in the open-field locomotor test, lower anxiety-like behavior in the elevated plus maze test, and significantly prolonged latencies in the hot-plate test, and this effect was equal among males and females. In the contextual fear-conditioning test, whereas NTS significantly reduced the enhanced freezing time due to NI in females, no significant difference in the freezing time between NI and NTS was found in males. These findings indicate that adequate tactile stimulation in early life plays an important role in the prevention of disturbances in the behavioral and emotional responses to environmental stimuli in adulthood induced by early adverse experiences.

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    • "Massage therapy involves kinesthetic or sensory stimulation [42], an intervention equivalent to tactile stimulation (TS) in animal studies. Interestingly, animal studies have shown TS to be an effective measure of protection against cortical injury [43] [44] and anxiety [45]. TS has also been shown to stimulate maturation in preterm and newborn animals [46] [47], and even alter the behavioral and neuroanatomical organization in non-brain injured rats [48]. "
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    ABSTRACT: Autism is a severe neurodevelopmental disorder with a population prevalence of 1 in 68, and dramatically increasing. While no single pharmacologic intervention has successfully targeted the core symptoms of autism, emerging evidence suggests that postnatal environmental manipulations may offer greater therapeutic efficacy. Massage therapy, or tactile stimulation (TS), early in life has repeatedly been shown to be an effective, low-cost, therapeutic approach in ameliorating the cognitive, social, and emotional symptoms of autism. While early TS treatment attenuates many of the behavioral aberrations among children with autism, the neuroanatomical correlates driving such changes are unknown. The present study assessed the therapeutic effects of early TS treatment on behavior and neuroanatomy using the valproic acid (VPA) rodent model of autism. Rats were prenatally exposed to VPA on gestational day 12.5 and received TS shortly following birth. Whereas TS reversed almost all the VPA-induced alterations in neuroanatomy, it failed to do so behaviorally. The TS VPA animals, when compared to VPA animals, did not exhibit altered or improved behavior in the delayed non-match-to-sample T-maze, Whishaw tray reaching, activity box, or elevated plus maze tasks. Anatomically, however, there were significant increases in dendritic branching and spine density in the medial prefrontal cortex, orbital frontal cortex, and amygdala in VPA animals following early TS treatment, suggesting a complete reversal or remediation of the VPA-induced effects in these regions. The results suggest that postnatal TS, during a critical period in development, acts as a powerful reorganization tool that can ameliorate the neuroanatomical consequences of prenatal VPA exposure. Copyright © 2014. Published by Elsevier B.V.
    Behavioural Brain Research 12/2014; 282. DOI:10.1016/j.bbr.2014.12.055 · 3.03 Impact Factor
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    • "These possibilities cannot be resolved using current data and need direct comparison of EE effects in wild rat populations in future. In laboratory animals, enrichment is generally thought to reduce anxiety and fear [58], [59], [60], [61], [62], contrary to the present report. These differences are probably due to the fact that we used a relatively shorter paradigm (14 days as opposed to 3–6 months) and also because we used a sensorial enrichment paradigm rather than social enrichment. "
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    ABSTRACT: Innate behaviors are shaped by contingencies built during evolutionary history. On the other hand, environmental stimuli play a significant role in shaping behavior. In particular, a short period of environmental enrichment can enhance cognitive behavior, modify effects of stress on learned behaviors and induce brain plasticity. It is unclear if modulation by environment can extend to innate behaviors which are preserved by intense selection pressure. In the present report we investigate this issue by studying effects of relatively short (14-days) environmental enrichment on two prominent innate behaviors in rats, avoidance of predator odors and ability of males to attract mates. We show that enrichment has strong effects on both the innate behaviors: a) enriched males were more avoidant of a predator odor than non-enriched controls, and had a greater rise in corticosterone levels in response to the odor; and b) had higher testosterone levels and were more attractive to females. Additionally, we demonstrate decrease in dendritic length of neurons of ventrolateral nucleus of hypothalamus, important for reproductive mate-choice and increase in the same in dorsomedial nucleus, important for defensive behavior. Thus, behavioral and hormonal observations provide evidence that a short period of environmental manipulation can alter innate behaviors, providing a good example of gene-environment interaction.
    PLoS ONE 05/2012; 7(5):e36092. DOI:10.1371/journal.pone.0036092 · 3.23 Impact Factor
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    • "From these findings, research has been directed at examining the remedial use of TS on brain injury [12] [13], and as a pain management tool for preterm neonates [14]. Additional research has examined the beneficial effects of TS on maladaptive affective responses such as anxiety [17], and tactile stimulation's ability to attenuate drug sensitization [18]. The mechanism underlying the effects of TS on the brain has not yet been determined, however, research has implicated fibroblast growth factor-2 (FGF-2) as a key facilitator of these effects. "
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    ABSTRACT: The purpose of this study was to examine the anatomical and behavioural sequelae in the normal brain associated with tactile stimulation treatment during development. Using a split litter design, male and female rats were randomly assigned to either the tactile stimulation group (tactile stimulation for 15 min, three times/day, from postnatal day 3 to 21), or the no-tactile stimulation group. In adulthood, the rats were tested on the Whishaw tray reaching task, activity box, novel object recognition, and elevated plus maze. Following behavioural testing, rats were sacrificed for Golgi-Cox analysis. Dendritic length, dendritic branching, and spine density were analyzed in two areas of the prefrontal cortex (mPFC and OFC) and spine density in the amygdala. Tactile stimulation significantly altered rat behaviour on the novel object recognition task and Whishaw tray reaching task, but failed to have an effect on behaviour in the elevated plus maze or activity box. Importantly, tactile stimulation dramatically altered dendritic morphology in the prefrontal cortex and amygdala of both male and female rats. Tactile stimulation significantly increased dendritic branching, dendritic length, and spine density in all brain regions examined. These findings demonstrate that similar to early adversity, positive experiences early in development can dramatically alter neuroplasticity.
    Behavioural brain research 03/2012; 231(1):86-91. DOI:10.1016/j.bbr.2012.02.043 · 3.03 Impact Factor
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