Prenatal substance abuse continues to be a significant problem in this country and poses important health risks for the developing fetus. The primary care pediatrician's role in addressing prenatal substance exposure includes prevention, identification of exposure, recognition of medical issues for the exposed newborn infant, protection of the infant, and follow-up of the exposed infant. This report will provide information for the most common drugs involved in prenatal exposure: nicotine, alcohol, marijuana, opiates, cocaine, and methamphetamine.

https://pediatrics.aappublications.org/content/pediatrics/early/2013/02/20/peds.2012-3931.full.pdf

Prenatal Substance Abuse: Short- and Long-term Effects on the Exposed Fetus

Once thought to produce global, nonspecific brain injury, drugs of abuse are now known to produce selective neuro-adaptations in particular brain regions. These neuro-adaptations are being closely examined for clues to the development, maintenance, and treatment of addiction. The hippocampus is an area of particular interest, as it is central to many aspects of the addictive process, including relapse to drug taking. A recently appreciated hippocampal neuro-adaptation produced by drugs as diverse as opiates and psychostimulants is decreased neurogenesis in the sub-granular zone (SGZ). While the role of adult-generated neurons is not clear, their functional integration into hippocampal circuitry raises the possibility that decreased adult SGZ neurogenesis may alter hippocampal function in such a way as to maintain addictive behavior or contribute to relapse. Here, we review the impact of opiates and psychostimulants on the different stages of cell development in the adult brain, as well as the different stages of the addictive process. We discuss how examination of drug-induced alterations of adult neurogenesis advances our understanding of the complex mechanisms by which opiates and psychostimulants affect brain function while also opening avenues for novel ways of assessing the functional role of adult-generated neurons. In addition, we highlight key discrepancies in the field and underscore the necessity to move "beyond BrdU"--beyond merely counting new hippocampal cells labeled with the S phase marker bromodeoxyuridine--so as to probe mechanistic questions about how drug-induced alterations in adult hippocampal neurogenesis occur and what the functional ramifications of alterations in neurogenesis are for addiction.

Opiates, psychostimulants, and adult hippocampal neurogenesis: Insights for addiction and stem cell biology.

AIM To assess outcome at 5–6 years in a cohort of very preterm infants ( METHODS Assessments were made on 87 children at 5–6 years who had been recruited in the neonatal period to two sequential controlled studies (1989–92). Infants requiring mechanical ventilation had been randomly allocated to receive either morphine (n=62) or other (n=33) solutions starting on the first day of life. Each child was seen by a single experienced observer and assessed at 5–6 years using the WPPSI-R, Movement ABC, and the Child Behaviour Checklist. The performance of children exposed to morphine was compared with that of those in the non-morphine group. Blood samples for thyroid stimulating hormone (TSH) measurement were obtained from children whose parents gave consent. RESULTS There was no significant difference in any of the three test scales between infants in the two groups, but there was a trend towards better performance in all three tests in the morphine group. Assessment of TSH values in a subgroup of the survivors showed no difference in thyroid function between the two groups. CONCLUSION Exposure to morphine in the neonatal period to facilitate mechanical ventilation does not seem to have any adverse effects on intelligence, motor function, or behaviour when these children are assessed at 5–6 years of age.

https://fn.bmj.com/content/fetalneonatal/79/1/F40.full.pdf

Outcome at 5–6 years of prematurely born children who received morphine as neonates

HIV-1 infection predisposes the central nervous system to damage by opportunistic infections and environmental insults. Such maladaptive plasticity may underlie the exaggerated comorbidity seen with HIV-1 infection and opioid abuse. Although morphine and HIV-1 Tat synergize at high concentrations to increase neuronal death in vitro, we questioned whether chronic low Tat exposure in vivo might contribute to the spectrum of neuropathology through sublethal neuronal injury. We used a doxycycline-driven, inducible, HIV-1 Tat transgenic mouse, in which striatal neuron death was previously shown to be absent, to examine effects of differential Tat expression, alone and combined with morphine. Low constitutive Tat expression caused neurodegeneration; higher levels induced by 7 days of doxycycline significantly reduced dendritic spine numbers. Moreover, Tat expression widely disrupted the endogenous opioid system, altering μ and κ, but not δ, opioid receptor and proopiomelanocortin, proenkephalin, and prodynorphin transcript levels in cortex, hippocampus, and striatum. In addition to markedly reducing spine density by itself, morphine amplified the effect of higher levels of Tat on spines, and also potentiated Tat-mediated dendritic pathology, thus contributing to maladaptive neuroplasticity at multiple levels. The dendritic pathology and reductions in spine density suggest that sustained Tat ± morphine exposure underlie key aspects of chronic neurodegenerative changes in neuroAIDS, which may contribute to the exacerbated neurological impairment in HIV patients who abuse opioids.

Interactive comorbidity between opioid drug abuse and HIV-1 Tat: chronic exposure augments spine loss and sublethal dendritic pathology in striatal neurons.

Recent advances in neonatal intensive care include and are partly attributable to growing attention for comfort and pain control in the term and preterm infant requiring intensive care. Limitation of painful procedures is certainly possible, but most critically ill infants require unavoidable painful or stressful procedures such as intubation, mechanical ventilation, or catheterization. Many analgesics (opioids and nonsteroidal anti-inflammatory drugs) and sedatives (benzodiazepines and other anesthetic agents) are available but their use varies considerably among units. This review summarizes current experimental knowledge on the effects of sedative and analgesic drugs on brain development and reviews clinical evidence that speaks for or against the use of common analgesic and sedative drugs in the NICU but avoids any discussion of anesthesia during surgery. Risk/benefit ratios of intermittent boluses or continuous infusions for the commonly used sedative and analgesic agents are discussed in the light of clinical and experimental studies. The limitations of extrapolating experimental results from animals to humans must be considered while making practical recommendations based on the currently available evidence.

/pdf/use-of-analgesic-and-sedative-drugs-in-the-nicu-integrating-577n4wlaxd.pdf

Use of analgesic and sedative drugs in the NICU: integrating clinical trials and laboratory data.

Perinatal morphine administration affects neuronal growth in the developing animal. Neuronal packing density was reduced by morphine treatment in both primary somatosensory cortex and preoptic area of the hypothalamus. However, glial packing density was increased, but only in hypothalamus, which could reflect greater severity of opiate-induced neurotoxicity in hypothalamus. Cortical pyramidal neurons show morphine-induced reduction of basilar dendritic growth limited to late-developing terminal branches. This effect is completely reversed by concurrent naltrexone administration. This selective effect could be caused by morphine acting at opiate receptors to inhibit extrinsic determinants of dendritic growth (e.g., afferent supply). The ontogeny of opiate receptors is also affected by perinatal morphine administration in a regionally-dependent manner. Mureceptors are downregulated by morphine in hypothalamus, but not in cortex. Differential maturity of receptors in these regions could be a factor in such differential drug effects. Therefore, different critical periods for opiate action in different regions of the developing brain could exist.

Ricalde Aa

Papers

Effects of opiates on brain development.