Insulin and insulin-like growth factor-1 increased in preterm neonates following massage therapy

Enriched early life experiences reduce adult anxiety-like behavior in rats: a role for insulin-like growth factor 1

Early life experiences can affect brain development, contributing to shape interindividual differences in stress vulnerability and anxiety-like behavior. In rodents, high levels of maternal care have long-lasting positive effects on the behavior of the offspring and stress response; post-weaning rearing in an enriched environment (EE) or massage counteract the negative effects of maternal separation or prenatal stressors. We recently found that insulin-like growth factor 1 (IGF-1) is a key mediator of early EE or massage on brain development. Whether early enrichment of experience can induce long-lasting effects on anxiety-like behavior and whether IGF-1 is involved in these effects is not known. We assessed anxiety-like behavior by means of the elevated plus maze in control adult rats and in adult rats subjected to early EE or to massage. We found that both EE and massage reduced adult anxiety-like behavior. Early IGF-1 systemic injections in rat pups reared in standard condition mimic the effects of EE and massage, reducing anxiety-like behavior in the adult; blocking early IGF-1 action in massaged and EE animals prevents massage and EE effects. In EE and IGF-1-treated animals, we assessed the hippocampal expression of glucocorticoid receptors (GRs) at postnatal day 12 (P12) and P60, finding a significantly higher GR expression at P60 for both treatments. These results suggest that IGF-1 could be involved in mediating the long-lasting effects of early life experiences on vulnerability/resilience to stress in adults.

Mechanical-tactile stimulation (MTS) intervention in a neonatal stress model alters adult adipose tissue deposition and prevents hyperinsulinemia in male rats

Preterm infants are exposed to numerous stressors during hospitalization and by term corrected gestational age they have lower body weight but a greater proportion of total body as well as abdominal visceral adipose tissue (VAT) accumulation. Greater abdominal VAT stores have a known association with metabolic syndrome. Mechanical-tactile stimulation (MTS) improves modulation of stress response in both humans and rodents. We hypothesize that MTS, administered during an established model of neonatal stress, would decrease stress-driven adiposity and prevent associated metabolic imbalances in adult rats. Neonatal stress, administered to rat pups from postnatal days 5 to P9, consisted of needle puncture and hypoxic/hyperoxic challenge during 60 min of maternal separation (STRESS; n=20). Mechanical-tactile stimulation (MTS; n=20) was administered to rat pups for 10 min during maternal separation in the stress protocol. Control animals received standard care (CTL; n=20). MRI measured adult (P120) abdominal total fat mass, subcutaneous (SAT) and visceral adipose tissue (VAT). Body weight and fasting serum adiponectin, leptin, glucose, insulin, and corticosterone were also measured. STRESS results in elevated VAT/SAT ratio compared to CTL but lower abdominal total fat mass and abdominal SAT. STRESS males experience hyperinsulinemia. Both STRESS and MTS had elevated leptin with lower adiponectin and corticosterone compared to CTL. In summary, neonatal stress promotes greater abdominal VAT accumulation and, in males, caused hyperinsulinemia and hypoadiponectinemia. Importantly, MTS normalized the VAT/SAT ratio and prevented hyperinsulinemia. We speculate that MTS ameliorates some of the negative metabolic consequences of early life perturbations due to neonatal stress exposure.

Massage improves growth quality by decreasing body fat deposition in male preterm infants

OBJECTIVES

To assess the effect of massage on weight gain and body fat deposition in preterm infants.

STUDY DESIGN

Preterm infants (29-32 weeks) were randomized to the massage group (n = 22, 12 girls, 10 boys) or the control group (n = 22, 12 girls, 10 boys). Treatment was masked with massage or control care administered twice-daily by licensed massage therapists (6 d/wk for 4 weeks). Body weight, length, Ponderal Index (PI), body circumferences, and skinfold thickness (triceps, mid-thigh, and subscapular [SSF]) were measured. Circulating insulin-like growth factor I, leptin, and adiponectin levels were determined by enzyme-linked immunosorbent assay. Daily dietary intake was collected.

RESULTS

Energy and protein intake as well as increase in weight, length, and body circumferences were similar. Male infants in the massage group had smaller PI, triceps skinfold thickness, mid-thigh skinfold thickness, and SSF and increases over time compared with control male infants (P < .05). Female infants in the massage group had larger SSF increases than control female infants (P < .05). Circulating adiponectin increased over time in control group male infants (group × time × sex interaction, P < .01) and was correlated to PI (r = 0.39, P < .01).

CONCLUSIONS

Twice-daily massage did not promote greater weight gain in preterm infants. Massage did, however, limit body fat deposition in male preterm infants. Massage decreased circulating adiponectin over time in male infants with higher adiponectin concentrations associated with increased body fat. These findings suggest that massage may improve body fat deposition and, in turn, growth quality of preterm infants in a sex-specific manner.

Brain plasticity in the developing brain

The developing normal brain shows a remarkable capacity for plastic change in response to a wide range of experiences including sensory and motor experience, psychoactive drugs, parent-child relationships, peer relationships, stress, gonadal hormones, intestinal flora, diet, and injury. The effects of injury vary with the precise age-at-injury, with the general result being that injury during cell migration and neuronal maturation has a poor functional outcome, whereas similar injury during synaptogenesis has a far better outcome. A variety of factors influence functional outcome including the nature of the behavior in question and the age at behavioral assessment as well as pre- and postinjury experiences. Here, we review the phases of brain development, how factors influence brain, and behavioral development in both the normal and perturbed brain, and propose mechanisms that may underlie these effects.

Maternal licking regulates hippocampal glucocorticoid receptor transcription through a thyroid hormone-serotonin-NGFI-A signalling cascade

Variations in parental care direct phenotypic development across many species. Variations in maternal pup licking/grooming (LG) in the rat regulate the development of individual differences in hypothalamic-pituitary-adrenal responses to stress. The adult offspring of mothers that show an increased frequency of pup LG have increased hippocampal glucocorticoid receptor (GR) expression and more modest pituitary-adrenal responses to stress. This parental effect is mediated by the epigenetic programming of a GR exon 1 promoter (exon 1(7)) through the binding of the transcription factor nerve growth factor-inducible factor A (NGFI-A). In this paper, we report that: (i) the association of NGFI-A with the exon 1(7) GR promoter is dynamically regulated by mother-pup interactions; (ii) this effect is mimicked by artificial tactile stimulation comparable to that provided by pup LG; (iii) that serotonin (5-HT) induces an NGFI-A-dependent increase in GR transcription in hippocampal neurons and NGFI-A overexpression is sufficient for this effect; and (iv) that thyroid hormones and 5-HT are key mediators of the effects of pup LG and tactile stimulation on NGFI-A binding to the exon 1(7) GR promoter in hippocampus. These findings suggest that pup LG directly activates 5-HT systems to initiate intracellular signalling pathways in the hippocampus that regulate GR transcription.

Tactile/kinesthetic stimulation (TKS) increases tibial speed of sound and urinary osteocalcin (U-MidOC and unOC) in premature infants (29-32weeks PMA)

Preterm delivery (<37 weeks post-menstrual age) is associated with suboptimal bone mass. We hypothesized that tactile/kinesthetic stimulation (TKS), a form of infant massage that incorporates kinesthetic movement, would increase bone strength and markers of bone accretion in preterm infants. Preterm, AGA infants (29-32 weeks) were randomly assigned to TKS (N=20) or Control (N=20). Twice daily TKS was provided 6 days per week for 2 weeks. Control infants received the same care without TKS treatment. Treatment was masked to parents, health care providers, and study personnel. Baseline and week two measures were collected for tibial speed of sound (tSOS, m/sec), a surrogate for bone strength, by quantitative ultrasound (Sunlight8000) and urine markers of bone metabolism, pyridinium crosslinks and osteocalcin (U-MidOC and unOC). Infant characteristics at birth and study entry as well as energy/nutrient intake were similar between TKS and Control. TKS intervention attenuated the decrease in tSOS observed in Control infants (p<0.05). Urinary pyridinium crosslinks decreased over time in both TKS and CTL (p<0.005). TKS infants experienced greater increases in urinary osteocalcin (U-MidOC, p<0.001 and unOC, p<0.05). We conclude that TKS improves bone strength in premature infants by attenuating the decrease that normally follows preterm birth. Further, biomarkers of bone metabolism suggest a modification in bone turnover in TKS infants in favor of bone accretion. Taken together, we speculate that TKS improves bone mineralization.

Neural correlates of a single-session massage treatment

The current study investigated the immediate neurophysiological effects of different types of massage in healthy adults using functional magnetic resonance imaging (fMRI). Much attention has been given to the default mode network, a set of brain regions showing greater activity in the resting state. These regions (i.e. insula, posterior and anterior cingulate, inferior parietal and medial prefrontal cortices) have been postulated to be involved in the neural correlates of consciousness, specifically in arousal and awareness. We posit that massage would modulate these same regions given the benefits and pleasant affective properties of touch. To this end, healthy participants were randomly assigned to one of four conditions: 1. Swedish massage, 2. reflexology, 3. massage with an object or 4. a resting control condition. The right foot was massaged while each participant performed a cognitive association task in the scanner. We found that the Swedish massage treatment activated the subgenual anterior and retrosplenial/posterior cingulate cortices. This increased blood oxygen level dependent (BOLD) signal was maintained only in the former brain region during performance of the cognitive task. Interestingly, the reflexology massage condition selectively affected the retrosplenial/posterior cingulate in the resting state, whereas massage with the object augmented the BOLD response in this region during the cognitive task performance. These findings should have implications for better understanding how alternative treatments might affect resting state neural activity and could ultimately be important for devising new targets in the management of mood disorders.

Paravertebral fascial massage promotes brain development of neonatal rats via the insulin-like growth factor 1 pathway

Massage in traditional Chinese medicine can promote body and brain development of premature and normal newborn infants. In the present study, neonatal rats (1 day old) underwent paravertebral fascial massage (15 consecutive days), followed by subcutaneous injection of insulin-like growth factor 1 receptor antagonist, JB1 (9 consecutive days). Paravertebral fascial massage significantly increased insulin-like growth factor 1 expression and cell proliferation in the subventricular zone of the lateral ventricle and dentate gyrus of the hippocampus. However, JB1 inhibited this increase. Results suggest that paravertebral fascial massage can promote brain development of neonatal rats via the insulin-like growth factor 1 pathway.

IV. Growth Failure in Institutionalized Children

Children within institutional care settings experience significant global growth suppression, which is more profound in children with a higher baseline risk of growth impairment (e.g., low birth weight [LBW] infants and children exposed to alcohol in utero). Nutritional insufficiencies as well as suppression of the growth hormone-insulin-like growth factor axis (GH-IGF-1) caused by social deprivation likely both contribute to the etiology of psychosocial growth failure within these settings. Their relative importance and the consequent clinical presentations probably relate to the age of the child. While catch-up growth in height and weight are rapid when children are placed in a more nurturing environment, many factors, particularly early progression through puberty, compromise final height. Potential for growth recovery is greatest in younger children and within more nurturing environments where catch-up in height and weight is positively correlated with caregiver sensitivity and positive regard. Growth recovery has wider implications for child well-being than size alone, because catch-up in height is a positive predictor of cognitive recovery as well. Even with growth recovery, persistent abnormalities of the hypothalamic-pituitary-adrenal system or the exacerbation of micronutrient deficiencies associated with robust catch-up growth during critical periods of development could potentially influence or be responsible for the cognitive, behavioral, and emotional sequelae of early childhood deprivation. Findings in growth-restricted infants and those children with psychosocial growth are similar, suggesting that children experiencing growth restriction within institutional settings may also share the risk of developing the metabolic syndrome in adulthood (obesity, Type 2 diabetes mellitus, hypertension, heart disease). Psychosocial deprivation within any care-giving environment during early life must be viewed with as much concern as any severely debilitating childhood disease.

IV. Growth Failure in Institutionalized Children

Children within institutional care settings experience significant global growth suppression, which is more profound in children with a higher baseline risk of growth impairment (e.g., low birth weight [LBW] infants and children exposed to alcohol in utero). Nutritional insufficiencies as well as suppression of the growth hormone-insulin-like growth factor axis (GH-IGF-1) caused by social deprivation likely both contribute to the etiology of psychosocial growth failure within these settings. Their relative importance and the consequent clinical presentations probably relate to the age of the child. While catch-up growth in height and weight are rapid when children are placed in a more nurturing environment, many factors, particularly early progression through puberty, compromise final height. Potential for growth recovery is greatest in younger children and within more nurturing environments where catch-up in height and weight is positively correlated with caregiver sensitivity and positive regard. Growth recovery has wider implications for child well-being than size alone, because catch-up in height is a positive predictor of cognitive recovery as well. Even with growth recovery, persistent abnormalities of the hypothalamic-pituitary-adrenal system or the exacerbation of micronutrient deficiencies associated with robust catch-up growth during critical periods of development could potentially influence or be responsible for the cognitive, behavioral, and emotional sequelae of early childhood deprivation. Findings in growth-restricted infants and those children with psychosocial growth are similar, suggesting that children experiencing growth restriction within institutional settings may also share the risk of developing the metabolic syndrome in adulthood (obesity, Type 2 diabetes mellitus, hypertension, heart disease). Psychosocial deprivation within any care-giving environment during early life must be viewed with as much concern as any severely debilitating childhood disease.

The effects of preterm infant massage on brain electrical activity

AIM

Early intervention programmes based on the manipulation of the extra-uterine environment have been used in preterm infants with the aim of improving development and functional outcome. Infant massage, among them, has proved effective for weight gain and reduced length of stay in the neonatal intensive care unit. We have recently shown that infant massage accelerates brain maturation of low-risk preterm infants without brain abnormalities as measured by global parameters of electroencephalography (EEG) activity. In the present study we further analyse the same cohort of preterm infants, testing the hypothesis that massage determines changes in EEG spectral activity, a highly sensitive index of brain maturation.

METHOD

Infants were randomly allocated to a massage or comparison group. Intervention consisted of standard care only (comparison group) or standard care plus infant massage (massage group). Massage was started at around 10 days after birth and was provided for 12 days during a 2-week period. EEG was performed at around 1 and 4 weeks, i.e. before and after intervention. Spectral EEG analysis was performed on 80 seconds of active sleep, applying the fast Fourier transform on the signal obtained from eight monopolar derivations.

RESULTS

The modification in global EEG spectral power between the two assessments was significantly different for the two groups, especially for the delta band activity; the spectral power did not change in massaged infants although, not surprisingly, it decreased significantly in the comparison group, as shown by previous studies.

INTERPRETATION

We propose that massage intervention affects the maturation of brain electrical activity and favours a process more similar to that observed in utero in term infants.

Mechanical-tactile stimulation (MTS) intervention in a neonatal stress model improves long-term outcomes on bone

OBJECTIVES

Neonatal stress impairs postnatal bone mineralization. Evidence suggests that mechanical tactile stimulation (MTS) in early life decreases stress hormones and improves bone mineralization. Insulin-like growth factor (IGF1) is impacted by stress and essential to bone development. We hypothesized that MTS administered during neonatal stress would improve bone phenotype in later life. We also predicted an increase in bone specific mRNA expression of IGF1 related pathways.

METHODS

Neonatal stress (STRESS) and MTS (STRESS+10 min of MTS) were given from D6 to D10 of rat life and tissue was harvested on D60 of life. Dual energy x-ray absorptiometry (DXA), bone morphometry, serum osteocalcin, type I procollagen N-terminal propeptide (PINP), tartrate-resistant acid phosphatase (TRAP), and bone and liver mRNA levels of IGF1, IGF1 receptor (IGF1R), and growth hormone receptor (GHR) were measured.

RESULTS

Stress resulted in reduced bone area and bone mineral content (BMC) compared to naive control (CTL). MTS intervention increased BMC and tibial growth plate width compared to STRESS. MTS also resulted in higher osteocalcin, and, in males, lower TRAP (p<0.05). MTS resulted in three-fold, two-fold, and six-fold higher bone specific IGF1, IGF1R, and GHR, respectively (p ≤ 0.001) compared to STRESS.

CONCLUSIONS

MTS in early postnatal life improves long-term bone mineralization. IGF1 and related pathways may explain improved BMC.

Potential underlying mechanisms for greater weight gain in massaged preterm infants

In this paper, potential underlying mechanisms for massage therapy effects on preterm infant weight gain are reviewed. Path analyses are presented suggesting that: (1) increased vagal activity was associated with (2) increased gastric motility, which, in turn, was related to (3) greater weight gain; and (4) increased IGF-1 was related to greater weight gain. The change in vagal activity during the massage explained 49% of the variance in the change in gastric activity. And, the change in vagal activity during the massage explained 62% of the variance in the change in insulin. That the change in gastric activity was not related to the change in insulin suggests two parallel pathways via which massage therapy leads to increased weight gain: (1) insulin release via the celiac branch of the vagus; and (2) increased gastric activity via the gastric branch of the vagus.

Preterm infant massage therapy research: a review

In this paper, preterm infant massage therapy studies are reviewed. Massage therapy has led to weight gain in preterm infants when moderate pressure massage was provided. In studies on passive movement of the limbs, preterm infants also gained significantly more weight, and their bone density also increased. Research on ways of delivering the massage is also explored including using mothers versus therapists and the added effects of using oils. The use of mothers as therapists was effective in at least one study. The use of oils including coconut oil and safflower oil enhanced the average weight gain, and the transcutaneous absorption of oil also increased triglycerides. In addition, the use of synthetic oil increased vagal activity, which may indirectly contribute to weight gain. The weight gain was associated with shorter hospital stays and, thereby, significant hospital cost savings. Despite these benefits, preterm infant massage is only practiced in 38% of neonatal intensive care units. This may relate to the underlying mechanisms not being well understood. The increases noted in vagal activity, gastric motility, insulin and IGF-1 levels following moderate pressure massage are potential underlying mechanisms. However, those variables combined do not explain all of the variance in weight gain, highlighting the need for additional mechanism studies.

Teaching Chilean mothers to massage their full-term infants: effects on maternal breast-feeding and infant weight gain at age 2 and 4 months

The purpose of this study was to evaluate the effects of massage on infant weight gain and exclusive maternal breast-feeding of an intervention that involved teaching mothers to massage their full-term infants. The sample included 100 healthy newborn infants who were receiving primary healthcare at 3 health centers in a low-income neighborhood of Santiago, Chile. The control group included 65 infants and the massage group included 35 infants. During their second well-child clinic visit, clinic nurses provided instruction to massage-group mothers about how to massage their infants, based on the methods of the Baby's First Massage program (http://www.babysfirstmassage.com/Scripts/default.asp). Mothers were encouraged to massage their infants for 10 to 15 minutes at least once a day, starting when their infants were 15 days old. There was no difference in the mean weights of the infants between the massage and control groups at baseline, but at age 2 months, massage group infants weighed significantly more than control-group infants. There were no weight differences between the 2 groups at age 4 months. There were no differences between the 2 groups on the incidence of exclusive maternal breast-feeding at age 2 or 4 months. The findings suggest that teaching mothers to massage their newborn infants may have a beneficial effect on the infant's early weight gain. There is a need for additional studies to evaluate the effect of maternal massage on other health and welfare outcomes for both mothers and infants.

Nurturing brain plasticity: impact of environmental enrichment

Environmental enrichment (EE) is known to profoundly affect the central nervous system (CNS) at the functional, anatomical and molecular level, both during the critical period and during adulthood. Recent studies focusing on the visual system have shown that these effects are associated with the recruitment of previously unsuspected neural plasticity processes. At early stages of brain development, EE triggers a marked acceleration in the maturation of the visual system, with maternal behaviour acting as a fundamental mediator of the enriched experience in both the foetus and the newborn. In adult brain, EE enhances plasticity in the cerebral cortex, allowing the recovery of visual functions in amblyopic animals. The molecular substrate of the effects of EE on brain plasticity is multi-factorial, with reduced intracerebral inhibition, enhanced neurotrophin expression and epigenetic changes at the level of chromatin structure. These findings shed new light on the potential of EE as a non-invasive strategy to ameliorate deficits in the development of the CNS and to treat neurological disorders.

Setting the pace for retinal development: environmental enrichment acts through insulin-like growth factor 1 and brain-derived neurotrophic factor

Environmental enrichment strongly affects visual system maturation both at retinal and cortical levels. Which molecular pathways are activated by an enriched environment (EE) to regulate visual system development has not been clarified. Here, we show that early [postnatal day 1 (P1) to P7] insulin-like growth factor 1 (IGF-1) injections in the eyes of non-EE rat pups mimic EE effects both in increasing BDNF levels in the retinal ganglion cell layer at P10 and in determining a more adult-like retinal acuity, assessed with pattern electroretinogram at P25. Blocking IGF-1 action in EE animals during the same early postnatal time window by injecting the IGF-1 receptor antagonist JB1 prevents EE effects both on BDNF expression and on retinal acuity maturation. Reducing BDNF expression in the retina of IGF-1-treated rats prevents IGF-1 effects on retinal acuity development. Finally, we show that tyrosine hydroxylase (TH) expression is increased in the retina of P10 EE and IGF-1-treated rats and that blocking TH expression in EE animals prevents EE from affecting retinal acuity development. Thus, early levels of IGF-1 play a key role in mediating EE effects on retinal development through an action that requires BDNF and involves dopaminergic amacrine cell network.

Massage accelerates brain development and the maturation of visual function

Environmental enrichment (EE) was shown recently to accelerate brain development in rodents. Increased levels of maternal care, and particularly tactile stimulation through licking and grooming, may represent a key component in the early phases of EE. We hypothesized that enriching the environment in terms of body massage may thus accelerate brain development in infants. We explored the effects of body massage in preterm infants and found that massage accelerates the maturation of electroencephalographic activity and of visual function, in particular visual acuity. In massaged infants, we found higher levels of blood IGF-1. Massage accelerated the maturation of visual function also in rat pups and increased the level of IGF-1 in the cortex. Antagonizing IGF-1 action by means of systemic injections of the IGF-1 antagonist JB1 blocked the effects of massage in rat pups. These results demonstrate that massage has an influence on brain development and in particular on visual development and suggest that its effects are mediated by specific endogenous factors such as IGF-1.