Neonatal handling on the first postnatal day leads to increased maternal behavior and fos levels in the brain of the newborn rat

Abstract

In the present work we employed Fos expression, an index of neuronal activity, to identify brain areas activated by a single exposure to "neonatal handling" on postnatal Day 1. Eight hours following "handling" there was an increase in the number of Fos positive cells in the hippocampus, the parietal and occipital cortex. We also recorded maternal behavior during the 8 hr following "handling." "Handled" pups received increased maternal licking during the 4 hr following the end of "handling." Furthermore, the number of Fos positive cells detected in each of the three brain areas 8 hr following "handling" was positively correlated with the amount of licking up to 8 hr following "handling." These results indicate that the increased maternal care could underlie the handling-induced increase in Fos. The Fos protein, acting as a transcription factor, controls the expression of downstream genes, whose products may mediate the effects of "neonatal handling" on the developing rat brain.

Rat dams exposed repeatedly to a daily brief separation from the pups exhibit increased maternal behavior, decreased anxiety and altered levels of receptors for estrogens (ERα, ERβ), oxytocin and serotonin (5-HT1A) in their brain

“…The results of the present study are in agreement with the literature reporting enhanced maternal behavior in litters following the daily repeated brief separation of the neonatal handling protocol (Smotherman, 1983;Levine, 1994;Liu et al, 1997;Pryce et al, 2001;Fenoglio et al, 2006;Garoflos et al, 2008) and support the validity of this neonatal manipulation for increasing maternal behavior. Interestingly, within a day experimental mothers exhibited the highest levels of maternal behavior immediately following the return of the pups to the nest.…”

“…Behavioral observations were performed as previously described (Garoflos et al, 2008) for 12 control and 12 experimental litters from PND1 until PND12 (Pryce et al, 2001), the time period during which maternal behavior is more intensely expressed (Cramer et al, 1990). Six 30 min observations were performed daily, ''blindly'' as to the experimental group.…”

“…Increased maternal behavior in the experimental group of dams was induced by subjecting them to a repeated brief separation (15 min daily) from their pups on postnatal days 1 to 22, as in the ''neonatal handling'' protocol (Levine, 1957). This experimental manipulation has been used extensively since its first description in 1957 and it is clearly established that it results in increased maternal behavior (Smotherman, 1983;Levine, 1994;Liu et al, 1997;Pryce et al, 2001;Fenoglio et al, 2006;Garoflos et al, 2008). Moreover, we investigated the effect of the daily repeated brief separation experience during the lactation period on the anxiety of the mother by determining on postnatal day 12 and 22 the behavior of the dams in the elevated plus maze.…”

Maternal care effects on SNB motoneuron development: The mediating role of sensory afferent distribution and activity

“…Specifically, anogenital stroking or stimulation of perineal nerves have been shown to evoke Fos expression in the spinal cord and brain (Rampin et al, 1997; Caba et al, 2003), and Fos expression in several brain regions has been shown to positively correlate with the amount of maternal licking received (Garoflos et al, 2008). In this experiment, we found that 60 s of licking-like tactile stimulation of the perineum of pups produced a significant increase in Fos-expression in the spinal cord, specifically in the area of the SNB dendritic field.…”

Interação entre deficiência de ferro e estimulação tátil: avaliação ultraestrutural do nervo óptico de ratos Wistar no período pós-natal precoce

“…Com relação a influencia da estimulação tátil no peso corporal dos filhotes, a análise mostrou que não houve diferenças entre os filhotes estimulados e não estimulados, resultado esse que corrobora os estudos de Silveira et al, (2004;2006), Imanaka et al (2008), Horiquini-Barbosa e Lachat (2016) e Horiquini- . No entanto, em contraste aos achados deste estudo, alguns autores relatam o aumento de peso corporal em animais que foram expostos à estimulação tátil (Panagiotaropoulos et al, 2004;Soares et al, 2012 (Levine, 1994;Liu et al, 1997;Pryce et al, 2001;Garoflos et al, 2008).…”