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.
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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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.09/2011; 18(2):127-137.
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ABSTRACT: In rodents, the disruption of social rearing conditions before normal weaning induces emotional behavioral abnormalities, such as anxiety, motor activity dysregulation, and stress vulnerability. The beneficial effects of exercise after normal weaning on emotional regulation have been well documented. However, effects of exercise before normal weaning on emotion have not been reported. We examined whether voluntary wheel running (R) during social isolation after early weaning (early weaning/isolation; EI) from postnatal day (PD) 14-30 could prevent EI-induced emotional behavioral abnormalities in Sprague-Dawley rats. Compared with control rats reared with their dam and siblings until PD30, rats performed R during EI (EI+R) and EI rats demonstrated greater locomotion and lower grooming activity in the open-field test (OFT) during the juvenile period. Juvenile EI±R rats showed greater learned helplessness (LH) after exposure to inescapable stress (IS; electric foot shock) than IS-exposed control and EI rats. In contrast, EI rats showed increased locomotion in the OFT and LH after exposure to IS compared with control rats during adulthood; this was not observed in EI±R rats. Both EI and EI±R rats exhibited greater rearing activity in the OFT than controls during adulthood. EI did not increase anxiety in the OFT and elevated plus-maze. These results suggested that R during EI until normal weaning prevented some of the EI-induced behavioral abnormalities, including hyperlocomotor activity and greater LH, during adulthood but not in the juvenile period.Behavioural brain research 02/2014; DOI:10.1016/j.bbr.2014.02.007 · 3.39 Impact Factor