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

ABSTRACT 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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    • "Los hallazgos son congruentes con los resultados de diferentes estudio en los que se reporta que las hembras presentan mayor ansiedad que los machos, evaluando la respuesta de congelamiento en condicionamiento pavloviano de miedo (Aguilar et al., 2003, Markus & Zecevic, 1997; Pryce et al., 1999; Wiltgen et al., 2001) y en otras medidas de ansiedad, tomadas a partir de pruebas como campo abierto (Mashoodh, Sinal, & Perrot-Sinal, 2009; Olivier et al., 2008) y laberinto elevado en cruz (Bowman, Micik, Gautreaux, Fernandez & Luine, 2009; Moreno, Lamprea, & Dueñas, 2009). Aunque contrario a los resultados que evidencian en los machos niveles más altos de la respuesta de congelamiento que las hembras (Chang et al. 2009; Graham, Yoon, Lee, & Kim, 2009; Maren, DeOca, & Fanselow, 1994; Sorg, Swindell, Tshirgi, 2004) o estudios en los que no se observó diferencias sexuales significativas durante la adquisición de miedo (Imanaka et al., 2008; Milad et al., 2009). Adicionalmente, las diferencias podrían explicarse de acuerdo a Taylor et al. (2000) en cuanto a que los machos ante situaciones de peligro presentan mayor número de conductas de lucha/huida debido a la producción de andrógenos (como la testosterona) que se generan antes y/o después del nacimiento del individuo. "
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    ABSTRACT: Pavlovian fear conditioning is one of the most popular preclinical models in the study of Post-Traumatic Stress Disorder (PTSD). The aim of the present research was explore the sex differences that characterize PTSD by means of this experimental paradigm, as well as to offer a preliminary description of how these sex differences behave throughout development. Forty five native rats, of Wistar descent were used as subjects, with 18 males and 27 females approximately balanced by litter across the two experimental groups: adolescents and adults. The results show significant differences in the second measurement of the conditioned stimulus in the interaction between sex and age and to compare the tree measurements of the conditioned stimulus. Results are discussed regarding the discrepancies in the literature regarding the effect of the variables evaluated in the acquisition of Conditioned fear.
    Suma Psicologica 09/2011; 18(2):127-137.
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