Prenatal cannabinoid exposure: why expecting individuals should take a pregnancy pause from using cannabinoid products.

Cannabinoid use in all populations is increasing as legalization across the United States continues. Concerningly, there is a lack of caution provided by medical providers to pregnant individuals as to the impact the use of cannabinoids could have on the developing fetus. Research continues in both the preclinical and clinical areas, and is severely needed, as the potency of delta-9-tetrahydrocannabinol (THC), the primary psychoactive component of cannabis, has increased dramatically since the initial studies were completed. Thus far, clinical studies raise compelling evidence for short term memory deficits, impulse control issues, and attention deficiencies following prenatal cannabinoid exposure (PCE). These changes may be mediated through epigenetic modifications that not only impact the current offspring but could carry forward to future generations. While additional studies are needed, a pregnancy pause from cannabinoid products should be strongly recommended by providers to ensure the optimal health and well-being of our future generations.

Premature birth, homeostatic plasticity and respiratory consequences of inflammation.

Infants who are born premature can have persistent apnea beyond term gestation, reemergence of apnea associated with inflammation during infancy, increased risk of sudden unexplained death, and sleep disorder breathing during infancy and childhood. The autonomic nervous system, particularly the central neural networks that control breathing and peripheral and central chemoreceptors and mechanoreceptors that modulate the activity of the central respiratory network, are rapidly developing during the last trimester (22-37 weeks gestation) of fetal life. With advances in neonatology, in well-resourced, developed countries, infants born as young as 23 weeks gestation can survive. Thus, a substantial part of maturation of central and peripheral systems that control breathing occurs ex-utero in infants born at the limit of viability. The balance of excitatory and inhibitory influences dictates the ultimate output from the central respiratory network. We propose in this review that simply being born early in the last trimester can trigger homeostatic plasticity within the respiratory network tipping the balance toward inhibition that persists in infancy. We discuss the intersection of premature birth, homeostatic plasticity and biological mechanisms leading to respiratory depression during inflammation in former premature infants.

Metal-Assisted and Microwave-Accelerated Decrystallization of Pseudo-Tophus in Synthetic Human Joint Models.

In this paper, we tested a hypothesis that the metal-assisted and microwave-accelerated decrystallization (MAMAD) technique, based on the combined use of low-power medical microwave heating (MWH) and gold nanoparticles (Au NPs), can be used to decrystallize laboratory-prepared monosodium urate monohydrate crystal aggregate (pseudo-tophus) placed in three-dimensional (3D) synthetic human joint models. To simulate a potential treatment of chronic tophaceous gout using the MAMAD technique, we used three different 3D synthetic human joint models and assessed the percent mass reduction (PMR, i.e., decrystallization) of pseudo-tophus and microwave-induced synthetic skin patch damage after MAMAD sessions (a MAMAD session = 120 s of MWH in the presence of Au NPs). Our three synthetic joint models are: Model 1: Application of seven MAMAD sessions in a closed synthetic joint with a pseudo-bursa containing a pseudo-tophus submerged in a solution of 20 nm Au NPs followed by dehydration of pseudo-tophus after each MAMAD session to assess PMR. Model 2: Application of seven MAMAD sessions in a closed or open synthetic joint with a pseudo-bursa containing a pseudo-tophus submerged in a solution of Au NPs followed by intermittent dehydration of pseudo-tophus after seven MAMAD sessions to assess PMR. Model 3: Application of 18 MAMAD sessions in a rotated closed synthetic joint (three sides are heated separately) with a pseudo-bursa containing a pseudo-tophus submerged in a solution of Au NPs followed by dehydration after every three MAMAD sessions to assess PMR. After a single MAMAD session, pseudo-tophus exposed to MWH and Au NPs had an average PMR of 8.30% (up to an overall PMR of 15%), and microwave-induced damage to the synthetic skin can be controlled by the use of a sacrificial skin sample and by adjusting the duration and the number of the MAMAD sessions. Computational electromagnetic simulations predict a 10% absorption of electric field by the pseudo-tophus placed in the synthetic joint models, which led us to conclude that a medical microwave source with higher power than 20 W can potentially be used with the MAMAD technique.

Microwave Heating of Crystals with Gold Nanoparticles and Synovial Fluid under Synthetic Skin Patches.

Gout is a disease with elusive treatment options. Reduction of the size of l-alanine crystals as a model crystal for gouty tophi with the use of a monomode solid-state microwave was examined as a possible therapeutic aid. The effect of microwave heating on l-alanine crystals in the presence of gold nanoparticles (Au NPs) in solution and synovial fluid (SF) in a plastic pouch through a synthetic skin patch was investigated. In this regard, three experimental paradigms were employed: Paradigm 1 includes the effect of variable microwave power (5-10 W) and variable heating time (5-60 s) and Au NPs in water (20 nm size, volume of 10 µL) in a plastic pouch (1 × 2 cm2 in size). Paradigm 2 includes the effect of a variable volume of 20 nm Au NPs in a variable volume of SF up to 100 µL in a plastic pouch at a constant microwave power (10 W) for 30 s. Paradigm 3 includes the effect of constant microwave power (10 W) and microwave heating time (30 s), constant volume of Au NPs (100 µL), and variable size of Au NPs (20-200 nm) placed in a plastic pouch through a synthetic skin patch. In these experiments, an average of 60-100% reduction in the size of an l-alanine crystal (initial size = 450 µm) without damage to the synthetic skin or increasing the temperature of the samples beyond the physiological range was reported.

Data from three prospective longitudinal human cohorts of prenatal marijuana exposure and offspring outcomes from the fetal period through young adulthood.

This article includes data from three prospective longitudinal human cohorts of prenatal marijuana exposure (PME) and offspring outcomes from the fetal period through young adulthood. The table herein contains an overview of the major adverse effects associated with PME from the following human cohorts: (1) The Ottawa Prenatal Prospective Study (OPPS); (2) The Maternal Health Practices and Child Development Study (MHPCD); and (3) The Generation R Study (Gen R). In the OPPS, fetal gestational age was measured and age-appropriate standardized neuropsychological instruments were used to assess neonatal responses, and infant-child and adolescent-young adult cognitive and behavioral skills. In the MHPCD, birth length and weight, neonatal body length, and infant-child sleep, cognition, and behavioral parameters were measured. In the Gen R, birth weight and growth were measured, as were infant-child attention and aggression. The data in this article are in support of our report entitled "Prenatal Cannabis Exposure - The "First Hit" to the Endocannabinoid System" (K.A. Richardson, A.K. Hester, G.L. McLemore, 2016) [13].

Prenatal cannabis exposure - The "first hit" to the endocannabinoid system.

As more states and countries legalize medical and/or adult recreational marijuana use, the incidences of prenatal cannabis exposure (PCE) will likely increase. While young people increasingly view marijuana as innocuous, marijuana preparations have been growing in potency in recent years, potentially creating global clinical, public health, and workforce concerns. Unlike fetal alcohol spectrum disorder, there is no phenotypic syndrome associated with PCE. There is also no preponderance of evidence that PCE causes lifelong cognitive, behavioral, or functional abnormalities, and/or susceptibility to subsequent addiction. However, there is compelling circumstantial evidence, based on the principles of teratology and fetal malprogramming, suggesting that pregnant women should refrain from smoking marijuana. The usage of marijuana during pregnancy perturbs the fetal endogenous cannabinoid signaling system (ECSS), which is present and active from the early embryonic stage, modulating neurodevelopment and continuing this role into adulthood. The ECSS is present in virtually every brain structure and organ system, and there is also evidence that this system is important in the regulation of cardiovascular processes. Endocannabinoids (eCBs) undergird a broad spectrum of processes, including the early stages of fetal neurodevelopment and uterine implantation. Delta-9-tetrahydrocannabinol (THC), the psychoactive chemical in cannabis, enters maternal circulation, and readily crosses the placental membrane. THC binds to CB receptors of the fetal ECSS, altering neurodevelopment and possibly rewiring ECSS circuitry. In this review, we discuss the Double-Hit Hypothesis as it relates to PCE. We contend that PCE, similar to a neurodevelopmental teratogen, delivers the first hit to the ECSS, which is compromised in such a way that a second hit (i.e., postnatal stressors) will precipitate the emergence of a specific phenotype. In summary, we conclude that perturbations of the intrauterine milieu via the introduction of exogenous CBs alter the fetal ECSS, predisposing the offspring to abnormalities in cognition and altered emotionality. Based on recent experimental evidence that we will review here, we argue that young women who become pregnant should immediately take a "pregnant pause" from using marijuana.

Novel pharmacotherapeutic strategies for treatment of opioid-induced neonatal abstinence syndrome.

The non-medical use of prescription drugs, in general, and opioids, in particular, is a national epidemic, resulting in enormous addiction rates, healthcare expenditures, and overdose deaths. Prescription opioids are overly prescribed, illegally trafficked, and frequently abused, all of which have created a new opioid addiction pathway, adding to the number of opioid-dependent newborns requiring treatment for neonatal abstinence syndrome (NAS), and contributing to challenges in effective care in maternal and fetal/neonatal (M-F/N) medicine. The standard of care for illicit or prescription opioid dependence during pregnancy is opioid agonist (methadone or buprenorphine) substitution therapy, which are also frequently abused. The next generation of pharmacotherapies for the treatment of illicit or prescription opioid addiction in the M-F/N interactional dyad must take into consideration the interplay between genetic, epigenetic, and environmental factors. Addiction to illicit drugs during pregnancy presents unique challenges to effectively treat the mother, and the developing fetus and infant after delivery. New pharmacotherapies should be safe to the developing fetus, effective in treating the physical and psychological consequences of addiction in the mother, and reduce the incidence and severity of NAS in the infant after birth. More pharmacotherapeutic options should be available to the physician such that a more individualized rather than a one-drug/strategy-fits-all approach can be used. A myriad of new and exciting pharmacotherapeutic strategies for the treatment of opioid dependence and addiction are on the horizon. This review focuses on such three strategies: (i) pharmacotherapeutic targeting of the serotonergic system; (ii) mixed opioid immunotherapeutics (vaccines); (iii) pharmacogenomics as a therapeutic strategy to insure personalized care. We review and discuss how these strategies may offer additional treatment modalities for the treatment of M-F/N during pregnancy and the treatment of the infant after birth.

Neonatal animal models of opiate withdrawal.

The symptoms of opiate withdrawal in infants are defined as neonatal abstinence syndrome (NAS). NAS is a significant cause of morbidity in term and preterm infants. Factors, such as polysubstance abuse, inadequate prenatal care, nutritional deprivation, and the biology of the developing central nervous system contribute to the challenge of evaluating and treating opiate-induced alterations in the newborn. Although research on the effects of opiates in neonatal animal models is limited, the data from adult animal models have greatly contributed to understanding and treating opiate tolerance, addiction, and withdrawal in adult humans. Yet the limited neonatal data that are available indicate that the mechanisms involved in these processes in the newborn differ from those in adult animals, and that neonatal models of opiate withdrawal are needed to understand and develop effective treatment regimens for NAS. In this review, the behavioral and neurochemical evidence from the literature is presented and suggests that mechanisms responsible for opiate tolerance, dependence, and withdrawal differ between adult and neonatal models. Also reviewed are studies that have used neonatal rodent models, the authors' preliminary data based on the use of neonatal rat and mouse models of opiate withdrawal, and other neonatal models that have been proposed for the study of neonatal opiate withdrawal.

Ontogeny of retrograde labeled chemoafferent neurons in the newborn rat nodose-petrosal ganglion complex: an ex vivo preparation.

Hypoxic chemosensitivity of the peripheral arterial chemoreceptors in the carotid body is developmentally regulated. Essential neural elements of the chemotransducing unit in the carotid body consist of the Type I cell that depolarizes and releases neurotransmitters in response to hypoxemia and the chemoafferent fibers which form synapses with Type I cells, contain postsynaptic receptors and have cell bodies in the petrosal ganglion. While many properties of the Type I cells have been characterized during postnatal development, less is known about the effect of development on the number and properties of the chemoafferents since localization of the cell bodies of chemoafferents are intermingled with the cell bodies of other sensory neurons that innervate the upper airway. Here, we describe a novel ex vivo preparation that we have developed to retrogradely label cell bodies of chemoafferents in the petrosal ganglion with rhodamine dextran. With this technique, in newborn rats, we show that there is a three-fold increase in retrogradely labeled neurons in the nodose-petrosal ganglion complex from postnatal day (PND) 3-7 with a three-fold decrease by PND 14 (P < 0.001, ANOVA). Furthermore, greater than 85% of these retrogradely labeled neurons co-express TH mRNA in all age groups. This novel ex vivo technique circumvents many of the technical difficulties encountered with retrogradely labeling chemoafferents in small newborn animals in vivo, and provides a method to identify and characterize essential neural components of the chemotranductive unit of the peripheral arterial chemoreceptors.

Cannabinoid receptor expression in peripheral arterial chemoreceptors during postnatal development.

Prenatal exposure to tobacco smoke increases risk of sudden infant death syndrome (SIDS). Marijuana is frequently smoked in conjunction with tobacco, and perinatal exposure to marijuana is associated with increased incidence of SIDS. Abnormalities in peripheral arterial chemoreceptor responses during sleep may be operative in infants at risk for SIDS, and nicotine exposure adversely affects peripheral arterial chemoreceptor responses. To determine whether marijuana could potentially affect the activity of peripheral arterial chemoreceptors during early postnatal development, we used in situ hybridization histochemistry to characterize the pattern and level of mRNA expression for cannabinoid type 1 receptor (CB1R) in the carotid body, superior cervical ganglia (SCG), and nodose-petrosal-jugular ganglia (NG-PG-JG) complex in newborn rats. We used immunohistochemistry and light, confocal, and electron microscopy to characterize the pattern of CB1R and tyrosine hydroxylase protein expression. CB1R mRNA expression was intense in the NG-PG-JG complex, low to moderate in the SCG, and sparse in the carotid body. With maturation, CB1R gene expression significantly increased (P < 0.01) in the NG-PG-JG complex. CB1R immunoreactivity was localized to nuclei of ganglion cells in the SCG and NG-PG-JG complex, whereas tyrosine hydroxylase immunoreactivity was localized to the cytoplasm. Exposure to marijuana during early development could potentially modify cardiorespiratory responses via peripheral arterial chemoreceptors. The novel finding of nuclear localization of CB1Rs in peripheral ganglion cells suggests that these receptors may have an, as yet, undetermined role in nuclear signaling in sensory and autonomic neurons.

Maturation of peripheral arterial chemoreceptors in relation to neonatal apnoea.

Apnoea and periodic breathing are the hallmarks of breathing for the infant who is born prematurely. Sustained respiration is obtained through modulation of respiratory-related neurons with inputs from the periphery. The peripheral arterial chemoreceptors, uniquely and reflexly change ventilation in response to changes in oxygen tension. The chemoreflex in response to hypoxia is hyperventilation, bradycardia and vasoconstriction. The fast response time of the peripheral arterial chemoreceptors to changes in oxygen and carbon dioxide tension increases the risk of more periodicity in the breathing pattern. As a result of baseline hypoxaemia, peripheral arterial chemoreceptors contribute more to baseline breathing in premature than in term infants. While premature infants may have an augmented chemoreflex, infants who develop bronchopulmonary dysplasia have a blunted chemoreflex at term gestation. The development of chemosensitivity of the peripheral arterial chemoreceptors and environmental factors that might cause maldevelopment of chemosensitivity with continued maturation are reviewed in an attempt to help explain the physiology of apnoea of prematurity and the increased incidence of sudden infant death syndrome (SIDS) in infants born prematurely and those who are exposed to tobacco smoke.

Autonomic microganglion cells: a source of acetylcholine in the rat carotid body.

Hypoxic chemosensitivity of peripheral arterial chemoreceptors and the ventilatory response to O2 deprivation increases with postnatal development. Multiple putative neurotransmitters, which are synthesized in the carotid body (CB), are thought to mediate signals generated by hypoxia. Acetylcholine (ACh) is believed to be a major excitatory neurotransmitter participating in hypoxic chemosensitivity. However, it is not known whether ACh originates from type I cells in the CB. In these studies, we tested the hypothesis that choline acetyltransferase (ChAT) and vesicular ACh transporter (VAChT) mRNAs are expressed in the CB and that mRNA levels would increase with postnatal maturation or exposure to hypoxia. Semiquantitative in situ hybridization histochemistry and immunohistochemistry were used to localize cholinergic markers within neurons and cells of the rat CB, the nodose-petrosal-jugular ganglion complex, and the superior cervical ganglion up to postnatal day 28. We show that the pattern of distribution, in tissue sections, is similar for both ACh markers; however, the level of VAChT mRNA is uniformly greater than that of ChAT. VAChT mRNA and immunoreactivity are detected abundantly in the nodose-petrosal-jugular ganglion complex in a number of microganglion cells embedded in nerve fibers innervating the CB for all postnatal groups, whereas ChAT mRNA is detected in only a few of these cells. Contrary to our hypothesis, postnatal maturation caused a reduction in ACh trait expression, whereas hypoxic exposure did not induce the upregulation of VAChT and ChAT mRNA levels in the CB, microganglion, or within the ganglion complex. The present findings indicate that the source of ACh in the CB is likely within autonomic microganglion cells and cholinergic nerve terminals.

Increased high-affinity nicotinic receptor-binding in rats exposed to lead during development.

Receptor autoradiography and membrane radioligand-binding assays were used to determine the expression of nicotinic cholinergic receptors in the brains of weanling rats exposed to low-levels of lead (Pb) during development. Nicotinic receptors were identified with the frog toxin epibatidine (EB) that binds with high affinity to a variety of receptors containing alpha and beta subunits. Rat pups were exposed to Pb from their mothers given 750-ppm Pb in the diet beginning on gestational day 0 through postnatal day (PN) 21. Blood Pb levels ranged from 36.5 to 46.5 microg/dl in the PN21 pups, and this exposure did not alter their body weight when compared to control rats. Several brain regions identified by autoradiographic studies as having significant binding of EB were dissected from control and Pb-treated pups and used in saturation-binding experiments with membrane preparations to determine the affinity constant (K(d)) and maximal-binding capacity (B(max)) of [3H]EB. Results indicate that the B(max) of [3H]EB was increased in several brain regions in Pb-treated rat pups, without a significant effect on K(d) estimates. [3H]EB-binding to membranes from untreated rats was not affected by in vitro exposure to 20-microM Pb, indicating that the effect of Pb on [3H]EB-binding in vivo was not likely due to direct influence of free Pb remaining in the tissue at the time of assay. The data therefore suggest that expression of nicotinic receptors that bind [3H]EB were increased by developmental exposure to Pb. Several possible mechanisms for these effects and the potential toxicological significance are discussed.