Prenatal anxiety, breastfeeding and child growth and puberty: linking evolutionary models with human cohort studies.

Background: Stress experienced by mothers during pregnancy can have both immediate and long-term effects on child development, potentially mediated by breastfeeding.Aim: Using a UK birth cohort study, we asked how maternal stress relates to breastfeeding and consequences for growth and puberty onset.Subjects and methods: We analysed data from the Avon Longitudinal Study of Parents and Children, collected via questionnaires and clinic visits (N: 698-8,506). We used reports of prenatal anxiety, breastfeeding, early growth and age at menarche or first voice change. Confounding by maternal age, parity, smoking, education and body mass index (BMI) was considered.Results: Mothers with higher levels of reported anxiety were less likely to breastfeed (Odds ratio (OR): 0.83, 95% confidence interval (CI): 0.71, 0.97). Breastfed infants had slower growth before weaning, although growth differences were unclear thereafter. Being breastfed for more than six months was associated with later puberty onset in females (2.76 months later than non-breastfed; CI: 0.9, 4.63), although the association was attenuated by confounders and BMI (1.51 months, CI: -0.38, 3.40). No association between breastfeeding and puberty onset in males was found.Conclusion: Our studies fit results shown previously, and we consider these in light of evolutionary life history theory while discussing key challenges in such an approach.

Interventions for supporting the initiation and continuation of breastfeeding among women who are overweight or obese.

BACKGROUND: Exclusive breastfeeding is recommended for all infants until six months of age due to the many health benefits for both the mother and infant.Evidence suggests that mothers who are overweight (body mass index (BMI) 25.0 to 29.9 kg/m²) or obese (BMI ≥ 30.0 kg/m²) are less likely to initiate breastfeeding and to breastfeed for a shorter duration. Considering the rising prevalence of overweight and obesity globally and the known benefits of breastfeeding particularly in reducing the long-term risks of obesity and diabetes for infants, establishing effective ways to support and promote breastfeeding in women who are overweight or obese is paramount in achieving the goal of healthier communities. OBJECTIVES: To assess the effectiveness of interventions to support the initiation or continuation of breastfeeding in women who are overweight or obese. SEARCH METHODS: On 23 January 2019 we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP) and reference lists of retrieved trials. SELECTION CRITERIA: Randomised controlled trials (RCTs) and quasi-RCTs that compared interventions to support the initiation and continuation of breastfeeding in women who are overweight or obese. Interventions included social support, education, physical support, or any combination of these. Interventions were compared either with each other or against a control group. DATA COLLECTION AND ANALYSIS: We assessed all potential trials identified from the search strategy. Two review authors extracted data from each included trial and assessed risk of bias. We resolved discrepancies through discussion with the third review author. We assessed the quality of the evidence using the GRADE approach. MAIN RESULTS: We found no trials comparing one type of support versus another. We included seven RCTs (including one cluster-RCT) involving 831 women. The number of women in each trial ranged from 36 to 226. The trials were conducted in high-income countries: USA (5 trials); Denmark (1 trial) and Australia (1 trial), between 2006 and 2015. Three trials only included women who were obese prior to pregnancy and four trials included both women who were overweight and women who were obese. We judged risk of bias in the included trials to be mixed; only one trial was judged to be low risk of bias for random sequence generation, allocation concealment and attrition bias.Physical breastfeeding support (manual or electric breast pump) versus usual care (no breast pump)Very low-certainty evidence from one small trial (39 women) looking at a physical support intervention (manual or electric breast pump) versus usual care (no pump) means it is unclear whether physical support improves exclusive breastfeeding at four to six weeks (risk ratio (RR) 0.55, 95% confidence interval (CI) 0.20 to 1.51) or any breastfeeding at four to six weeks (RR 0.65, 95% CI 0.41 to 1.03). The trial did not report other important outcomes of interest in this review: non-initiation of breastfeeding, exclusive or any breastfeeding at six months postpartum.Multiple methods of breastfeeding support versus usual care Six trials (involving 792 women) used multiple methods of support including education and social support through telephone or face-to-face contact. One of these trials also provided physical support through providing a breast pump and a baby sling and one trial provided a small gift to the women at each trial visit. Support in the trials was provided by a professional (four trials) or a peer (two trials). One trial provided group support, with the other five trials supporting women individually. One trial (174 women) did not report on any of our main outcomes of interest.We are unclear about the effects of the intervention because we identified very low-certainty evidence for all of the important outcomes in this review: rate of non-initiation of breastfeeding (average RR 1.03, 95% CI 0.07 to 16.11; 3 trials, 380 women); exclusive breastfeeding at four to six weeks (average RR 1.21, 95% CI 0.83 to 1.77; 4 trials, 445 women); any breastfeeding at four to six weeks (average RR 1.04, 95% CI 0.57 to 1.89; 2 trials, 103 women); rate of exclusive breastfeeding at six months postpartum (RR 7.23, 95% CI 0.38 to 137.08; 1 trial, 120 women); and any breastfeeding at six months postpartum (average RR 1.42, 95% CI 1.08 to 1.87; 2 trials, 223 women).The included trials under the above comparisons also reported on some of this review's secondary outcomes but very low-certainty evidence means that we are unclear about the effects of the intervention on those outcomes. AUTHORS' CONCLUSIONS: There is insufficient evidence to assess the effectiveness of physical interventions, or multiple methods of support (social, educational or physical) for supporting the initiation or continuation of breastfeeding in women who are overweight or obese. We found no RCTs comparing one type of support to another type of support. All of our GRADE assessments resulted in very low-certainty evidence, with downgrading decisions based on limitations in trial design (e.g. risk of attrition bias), imprecision, inconsistency. The available trials were mostly of variable quality with small numbers of participants, confounded by poor adherence within both the intervention and control groups.Well designed, adequately powered research is needed to answer questions about the social, educational, physical support, or any combination of these interventions that could potentially help mothers who are overweight or obese to achieve optimal breastfeeding outcomes. We need trials that examine interventions designed specifically for women who are overweight or obese, delivered by people with training about how to overcome some of the challenges these women face when establishing and maintaining breastfeeding. Particular attention could be given to the assessment of antenatal interventions aimed at improving breastfeeding initiation in women with a raised BMI, and not just focusing on recruiting women who have an intention to breastfeed. Given that the majority of current trials were undertaken in the USA, further trials in a diverse range of countries and settings are required. Future trials need to give consideration to the theoretical basis of the intervention using established frameworks to enable replicability by others and to better determine the components of effective interventions.

Impaired recognition memory and cognitive flexibility in the rat L5-L6 spinal nerve ligation model of neuropathic pain.

BACKGROUND AND AIMS: Although neuropathic pain is known to negatively affect cognition, the neural mechanisms involved are poorly understood. Chronic pain is associated with changes in synaptic plasticity in the brain which may impact on cognitive functioning. The aim of this study was to model neuropathic pain in mid-aged rats using spinal nerve ligation (SNL). Following establishment of allodynia and hyperalgesia, behaviour was assessed in a battery of cognitive tests. Expression of the presynaptic protein, synaptophysin, and its colocalisation with the vesicular GABA and glutamate transporters (vGAT and vGLUT, respectively), was investigated in the medial prefrontal cortex (mPFC) and hippocampus. METHODS: Nine month old male Sprague Dawley rats underwent L5-L6 spinal nerve ligation or a sham procedure. Mechanical and cold allodynia and thermal hyperalgesia were assessed using von Frey, acetone and Hargreaves tests, respectively. Cognition was assessed in the novel-object recognition, air-puff passive avoidance and Morris water maze behavioural tasks. Immunohistochemistry was used to examine the expression of synaptophysin in the mPFC and CA1 region of the hippocampus and double labelling of synaptophysin and the vesicular transporters vGAT and vGlut was used to investigate the distribution of synaptophysin on GABAergic and glutamatergic neurons. RESULTS: SNL rats displayed impaired performance in the novel-object recognition task. Passive-avoidance responding, and spatial learning and memory in the Morris water maze, were unaffected by SNL surgery. However, in the water maze reversal task, pain-related impairments were evident during training and probe trials. SNL surgery was not associated with any differences in the expression of synaptophysin or its colocalisation with vGAT or vGLUT in the mPFC or the hippocampal CA1 region. CONCLUSIONS: These results suggest that the SNL model of neuropathic pain is associated with deficits in recognition memory and cognitive flexibility, but these deficits are not associated with altered synaptophysin expression or distribution in the mPFC and CA1. IMPLICATIONS: Cognitive complaints are common amongst chronic pain patients. Here we modelled cognitive impairment in a well-established animal model of neuropathic pain and investigated the neural mechanisms involved. A better understanding of this phenomenon is an important prerequisite for the development of improved treatment of patients affected.

Microinjection of 2-arachidonoyl glycerol into the rat ventral hippocampus differentially modulates contextually induced fear, depending on a persistent pain state.

The endogenous cannabinoid (endocannabinoid) system plays a key role in the modulation of aversive and nociceptive behaviour. The components of the endocannabinoid system are expressed throughout the hippocampus, a brain region implicated in both conditioned fear and pain. In light of evidence that pain can impact on the expression of fear-related behaviour, and vice versa, we hypothesised that exogenous administration of the endocannabinoid 2-arachidonoyl glycerol (2-AG) into the ventral hippocampus (vHip) would differentially regulate fear responding in the absence vs. the presence of formalin-evoked nociceptive tone. Fear-conditioned rats showed significantly increased freezing and a reduction in formalin-evoked nociceptive behaviour upon re-exposure to a context previously paired with footshock. Bilateral microinjection of 2-AG into the vHip significantly reduced contextually induced freezing in non-formalin-treated rats, and reduced formalin-evoked nociceptive behaviour in non-fear-conditioned rats. In contrast, 2-AG microinjection had no effect on fear responding in formalin-treated rats, and no effect on nociceptive behaviour in fear-conditioned rats. The inhibitory effect of 2-AG on fear-related behaviour, but not pain-related behaviour, was blocked by co-administration of the cannabinoid receptor 1 (CB1) antagonist/inverse agonist rimonabant. Tissue levels of the endocannabinoids N-arachidonoylethanolamide (anandamide, AEA) and 2-AG were similar in the vHip of fear-conditioned rats receiving formalin injection and the vHip of fear-conditioned rats receiving saline injection. However, the levels of AEA and 2-AG were significantly lower in the contralateral ventrolateral periaqueductal grey of formalin-treated fear-conditioned rats than in that of their saline-treated counterparts. These data suggest that 2-AG-CB1 receptor signalling in the vHip has an anti-aversive effect, and that this effect is abolished in the presence of a persistent pain state.

Behavioural, neurochemical and neuroendocrine effects of the endogenous ß-carboline harmane in fear-conditioned rats.

The putative endogenous imidazoline binding site ligand harmane enhances neuronal activation in response to psychological stress and alters behaviour in animal models of anxiety and antidepressant efficacy. However, the neurobiological mechanisms underlying harmane's psychotropic effects are poorly understood. We investigated the effects of intraperitoneal injection of harmane (2.5 and 10 mg/kg) on fear-conditioned behaviour, hypothalamo-pituitary-adrenal axis activity, and monoaminergic activity within specific fear-associated areas of the rat brain. Harmane had no significant effect on the duration of contextually induced freezing or 22 kHz ultrasonic vocalisations and did not alter the contextually induced suppression of motor activity, including rearing. Harmane reduced the duration of rearing and tended to increase freezing in non-fear-conditioned controls, suggesting potential sedative effects. Harmane increased plasma ACTH and corticosterone concentrations, and serotonin (in hypothalamus, amygdaloid cortex, prefrontal cortex and hippocampus) and noradrenaline (prefrontal cortex) content, irrespective of fear-conditioning. Furthermore, harmane reduced dopamine and serotonin turnover in the PFC and hypothalamus, and serotonin turnover in the amygdaloid cortex in both fear-conditioned and non-fear-conditioned rats. In contrast, harmane increased dopamine and noradrenaline content and reduced dopamine turnover in the amygdala of fear-conditioned rats only, suggesting differential effects on catecholaminergic transmission in the presence and absence of fear. The precise mechanism(s) mediating these effects of harmane remain to be determined but may involve its inhibitory action on monoamine oxidases. These findings support a role for harmane as a neuromodulator, altering behaviour, brain neurochemistry and neuroendocrine function.

Fear-induced suppression of nociceptive behaviour and activation of Akt signalling in the rat periaqueductal grey: role of fatty acid amide hydrolase.

The endocannabinoid system regulates nociception and aversion and mediates fear-conditioned analgesia (FCA). We investigated the effects of the fatty acid amide hydrolase (FAAH) inhibitor URB597, which inhibits the catabolism of the endocannabinoid anandamide and related N-acylethanolamines, on expression of FCA and fear and pain related behaviour per se in rats. We also examined associated alterations in the expression of the signal transduction molecule phospho-Akt in the periaqueductal grey (PAG) by immunoblotting. FCA was modelled by assessing formalin-evoked nociceptive behaviour in an arena previously paired with footshock. URB597 (0.3 mg/kg, i.p.) enhanced FCA and increased fear-related behaviour in formalin-treated rats. Conditioned fear per se in non-formalin-treated rats was associated with increased expression of phospho-Akt in the PAG. URB597 reduced the expression of fear-related behaviour in the early part of the trial, an effect that was accompanied by attenuation of the fear-induced increase in phospho-Akt expression in the PAG. Intra-plantar injection of formalin also reduced the fear-induced increase in phospho-Akt expression. These data provide evidence for a role of FAAH in FCA, fear responding in the presence or absence of nociceptive tone, and fear-evoked increases in PAG phospho-Akt expression. In addition, the results suggest that fear-evoked activation of Akt signalling in the PAG is abolished in the presence of nociceptive tone.

A role for the ventral hippocampal endocannabinoid system in fear-conditioned analgesia and fear responding in the presence of nociceptive tone in rats.

The endogenous cannabinoid (endocannabinoid) system plays an important role in fear-conditioned analgesia (FCA) and expression and extinction of conditioned fear. The hippocampus has an established role in both pain and conditioned fear and is a substrate for endocannabinoid activity. This study aimed to investigate the role of the endocannabinoid system in the ventral hippocampus (vHip) in FCA and in fear responding in the presence of nociceptive tone. Fear-conditioned rats displayed significantly increased freezing and 22-kHz ultrasonic vocalisation and a reduction in formalin-evoked nociceptive behaviour (ie, FCA) upon re-exposure to a context previously paired with footshock. Tissue levels of the endocannabinoids, anandamide, and 2-arachidonoylglycerol, as well as the fatty acid amide, palmitoylethanolamide, were significantly higher in the vHip of fear-conditioned rats compared with non-fear-conditioned controls. URB597 (inhibitor of fatty acid amide hydrolase [FAAH]), administered bilaterally into the vHip, significantly enhanced FCA during the entire trial and increased fear responding in formalin-treated rats early in the trial. The URB597-induced enhancement of FCA was blocked by intra-vHip administration of the cannabinoid(1) (CB(1)) receptor antagonist/inverse agonist rimonabant. Intra-vHip rimonabant alone had no effect on the expression of FCA, and URB597 did not significantly alter formalin-evoked nociceptive behaviour in non-fear-conditioned rats. These data suggest an important role for the endocannabinoid system in the vHip in FCA, whereby levels of 2-arachidonoylglycerol and the FAAH substrates palmitoylethanolamide and anandamide are increased in rats expressing FCA, and pharmacological inhibition of FAAH in the vHip enhances this form of endogenous analgesia via a CB(1) receptor-dependent mechanism.

Investigating the effects of distracting stimuli on nociceptive behaviour and associated alterations in brain monoamines in rats.

Distraction interventions are used clinically to relieve pain. Exposure to distracting stimuli causes withdrawal of attention from the painful stimulus and reduces perceived pain. However, the neurobiological mechanisms mediating distraction-induced analgesia are poorly understood due, in part, to a paucity of animal studies modelling this phenomenon. The present study investigated the effects of three distracting stimuli on formalin-evoked nociceptive behaviour and brain tissue monoamine levels in rats. The three distractors were: exposure to a novel environment, exposure to a novel object, and exposure, without contact, to another rat (conspecific). A control group, habituated to the test arena, was also included. Formalin-evoked nociceptive behaviour was significantly reduced in rats exposed to the novel object or novel arena, but not those exposed to the conspecific, compared with controls. Antinociception resulting from exposure to the novel object was of longer duration than that resulting from exposure to the novel arena. Failure to detect any distractor-induced effects on plasma corticosterone levels or aversive behaviours suggests that the stimuli used were non-stressful. HPLC analysis revealed that there was a significant reduction in serotonin and dopamine metabolites in the medial prefrontal cortex in animals exposed to the novel object. These results indicate that exposure to a novel object or arena reduces nociceptive behaviour in rats, effects accompanied by discrete alterations in serotonin and dopamine metabolites in the medial prefrontal cortex.

Orexin expression and function: glucocorticoid manipulation, stress, and feeding studies.

We investigated the effects of glucocorticoid manipulation on orexin-A-induced feeding and prepro-orexin mRNA levels in the lateral hypothalamic area (LHA) of the rat brain. Adrenalectomy (ADX) reduced orexin-A-induced feeding over 4 h by about 60%, compared with shams, an effect that was reversed by corticosterone (CORT) replacement. ADX had no effect on prepro-orexin mRNA levels in the LHA in either the morning or the evening; however, message was up-regulated by CORT in the morning but not the evening. An increased number of emulsion grains per cell in the LHA suggests that this is a specific increase in prepro-orexin mRNA and is not due to an increased number of cells expressing message. Prepro-orexin mRNA levels in the LHA were elevated 4 h after injection of lipopolysaccharide, compared with saline-injected controls. Partial but not complete abolition of orexin-A-induced feeding by ADX suggests that orexin-A-induced feeding may be mediated through glucocorticoid-dependent and glucocorticoid-independent pathways. In the morning increased prepro-orexin mRNA after CORT replacement demonstrates that orexin expression is sensitive to increased concentrations of glucocorticoids. However, the lack of effect of ADX on prepro-orexin mRNA levels suggests that endogenous glucocorticoids are not involved in tonic regulation of basal prepro-orexin expression. Overall our data constitute a body of evidence for an integrated relationship between central orexin expression, stress, glucocorticoid manipulation, and feeding patterns in the rat.