Supporting the Development of Grassroots Maternal and Childhood Health Leaders through a Public-Health-Informed Training Program.

The purpose of this research was to assess leadership growth (i.e., changes in personal capacity and social capital) among women living in high-risk infant mortality zip codes who completed a grassroots maternal and childhood health leadership (GMCHL) training program. We used semi-structured qualitative interviews and thematic analysis. Three major themes associated with the training program experience were identified: (1) building personal capacity and becoming community brokers; (2) linking and leveraging through formal organizations; and (3) how individual change becomes community change. Although many of the grassroots leaders were already brokers (i.e., connecting individuals to information/services), they were able to become community brokers by gaining new skills and knowledge about strategies to reduce adverse birth outcomes in their community. In particular, joining and participation in formal organizations aimed at improving community health led to the development of linking or vertical ties (e.g., "people in high places"). The grassroots leaders gained access to people in power, such as policymakers, which enabled leaders to access more resources and opportunities for themselves and their social networks. We outline the building blocks for supporting potential grassroots leaders by enhancing personal capacity and social capital, thus leading to increases in collective efficacy and collective action.

Grounding the Work of Grassroots MCH Leaders in Storytelling.

Our Grassroots Maternal and Child Health (MCH) Initiative works to build the capacity of individuals and organizations in zip codes with persistently high infant mortality rates to bring about systems change that will improve maternal and child health (MCH) outcomes. Foundational to the Initiative is the training and mentoring of local women to become Grassroots MCH Leaders. We greatly honor that these women possess community expertise, essential to the Initiative's success. Our training equips them with strategies they can use to bring about changes in social, economic, political, and/or cultural systems that underlie poor birth outcomes. One impactful strategy they learn is the use of critical narrative intervention (CNI). This approach, grounded in the crafting and sharing of stories, complements statistical, behavioral, and medical approaches to improve MCH outcomes. This article describes the impact of CNI within the Grassroots MCH Initiative. Drawing from 14 Grassroots MCH Leaders' narratives, we present five significant maternal traumas and influential supports in their surrounding contexts. We explore the leaders' reflections on the impact of story development and dissemination. Our findings reveal that situating CNI within the context of a grassroots initiative provides opportunities for leaders to use their stories to advocate for systems change. Personal MCH narratives provide a powerful and respectful approach to public health promotion, as they highlight important systems-level failures that need to be addressed to sustainability improve MCH outcomes.

Scoping Review to Identify Social Determinants of Maternal Health in Morocco.

To understand the mechanism of health inequities and their influence on maternal health, the Commission on Social Determinants of Health (CSDH) provides a framework to identify structural and intermediate causes of health inequity. This review maps and describes the current socioeconomic determinants of maternal health in Morocco according to the CSDH framework. A scoping study was carried out from six databases (Springer, Web of Science, Pubmed, Science Direct, Jstor, and Cochrane library) based on quantitative and qualitative research done since 1990. Structural factors such as women's employment and economic status, education level, culture, and gender equity were influenced by intermediary factors such as place of residence, age at marriage, maternal age at childbirth, and parity (either alone or in conjunction with other variables). Together these factors worked to influence maternal health service usage or affected maternal health outcomes. Power dynamics were identified in a variety of social situations that impacted access to health care for women across socioeconomic categories. Studies reveal how social determinants impact maternal health in Morocco. Addressing these determinants is required for sustainably improving maternal and infant health in Morocco.

Health insurance coverage and poverty status of postpartum women in the United States in 2019: an ACS-PUMS population-based cross-sectional study.

BACKGROUND: A quarter of United States (US) postpartum women still report unmet health care needs and health care unaffordability. We aimed to study associations between receipt of health insurance coverage and poverty status/receipt of government financial support and determine coverage gaps overall and by social factors among US postpartum women in poverty. METHODS: This study design is a cross-sectional study using secondary data. We included women who gave birth within the last 12 months from 2019 American Community Survey Public Use Microdata Sample. Poverty was defined as having an income-to-poverty ratio of less than 100%. We explored Medicaid/government medical assistance gaps among women in poverty. To examine the associations between Medicaid/government medical assistance (exposures) and poverty/government financial support (outcomes), we used age-, race-, and multivariable-adjusted logistic regression models. We also evaluated the associations of state, race, citizenship status, or language other than English spoken at home (exposures) with receipt of Medicaid/government medical assistance (outcomes) among women in poverty through multivariable-adjusted logistic regression. RESULTS: It was notable that 35.6% of US postpartum women in poverty did not have Medicaid/government medical assistance and only a small proportion received public assistance income (9.8%)/supplementary security income (3.1%). Women with Medicaid/government medical assistance, compared with those without the coverage, had statistically significantly higher odds of poverty [adjusted odds ratio (aOR): 3.15, 95% confidence interval (95% CI): 2.85-3.48], having public assistance income (aOR: 24.52 [95% CI: 17.31-34.73]), or having supplementary security income (aOR: 4.22 [95% CI: 2.81-6.36]). Also, among postpartum women in poverty, women in states that had not expanded Medicaid, those of Asian or other race, non-US citizens, and those speaking another language had statistically significantly higher odds of not receiving Medicaid/government medical assistance [aORs (95% CIs): 2.93 (2.55-3.37); 1.30 (1.04-1.63); 3.65 (3.05-4.38); and 2.08 (1.86-2.32), respectively]. CONCLUSIONS: Our results showed that the receipt of Medicaid/government medical assistance is significantly associated with poverty and having government financial support. However, postpartum women in poverty still had Medicaid/government medical assistance gaps, especially those who lived in states that had not expanded Medicaid, those of Asian or other races, non-US citizens, and other language speakers.

Heterogeneous effects of socio-economic and cultural factors on fertility differentials in Burundi and Morocco during their fertility transition periods: a retrospective, cross-sectional and comparative study.

Introduction: few studies have examined the factors influencing fertility differentials and the variation in their effects in countries with different socioeconomic and cultural backgrounds and different fertility transition paces. To address this gap, our study sought to first identify the factors that influenced fertility differentials in Morocco and Burundi during their fertility transition periods, and then to compare the effects of these factors between the two countries. Methods: using data from the 2003-4 Morocco and 2010 Burundi Demographic and Health Surveys, bivariable and multivariable Poisson regression analyses offset by the natural logarithm of the women´s age were performed to identify the socioeconomic and cultural factors that influenced fertility differentials in Morocco and Burundi during their fertility transition. Results: our main findings showed that the total number of children ever born ranged from 0 to 17 with a mean of 2.71 ± 2.89 in Burundi and from 0 to 16 with a mean of 1.88 ± 2.80 in Morocco. In Burundi, both socioeconomic and cultural factors like rural residence adjusted incident rate ratio (AIRR) = 1.159, 95% CI: 1.103 - 1.217, P=0.020), women´s illiteracy (AIRR=1.465, 95% CI: 1.241- 1.729, P <0.001) and agricultural profession (AIRR=1. 332, 95% CI: 1.263 - 1.401, P = 0.004), household poverty (AIRR= 1.381, 95% CI: 1.223 - 1.431, p<0.001), infant mortality (AIRR= 1.602, 95% CI: 1.562 - 1.643, p<0.001), early marriage (AIRR= 1.313, 95% CI: 1.264 - 1.364, p<0.001), lack of knowledge of any contraceptives (AIRR= 1.263, 95% CI: 1.125 - 1.310, p = 0.003) and failure to use modern contraceptives (AIRR= 1.520, 95% CI: 1.487 - 1.611, p<0.001) were associated with high number of children ever born. However, in Morocco socioeconomic factors like residence place, women´s agricultural profession and household poverty were not significant. In this country, women´s illiteracy (AIRR=1.428, 95% CI: 1.315 - 1.551, P <0.001), lack of access to mass media (AIRR= 1.241, 95% CI: 1.108 - 1.375, p = 0.006), infant mortality (AIRR=1.222, 95%CI: 1.184 - 1.361, p<0.001), early marriage (AIRR1.481, 95% CI: 1.435 - 1.529, p<0.001), lack of knowledge of any contraceptives (AIRR1.508, 95% CI: 1.409 - 1.613, p<0.001) and failure to use modern contraceptives (AIRR1.745, 95% CI: 1.627 - 1.863, p<0.001) were associated with high fertility but with different effects than in Burundi. Conclusion: the evidence from this study suggests that interventions to accelerate the fertility transition processes in Burundi and many other countries with slow fertility transitions should be designed and implemented according to each country's local context.

Applying a Maternal Standards of Care Audit Tool and Quality Improvement Process to Improve Healthcare for Pregnant Women in Prison.

Women are the fastest growing prison population, but little is known about the quality of maternal care for pregnant women in prison. In partnership with the Indiana Department of Correction (IDOC) Transitional Healthcare Team (THT), we developed a maternal standard of care (MSOC) audit tool to identify existing strengths and weaknesses and recommend evidence-based strategies for improvement. After creating the MSOC audit tool, we used it to audit 52 charts and conducted interviews of IDOC staff regarding maternal health care processes. Identified strengths include prenatal care, screening/treatment for sexually transmitted diseases and substance use disorders, contraception use, and health education. Mental and nutritional health care are areas of weakness. Staff motivation and community partnerships facilitate positive change, but a "punitive" culture, lack of resources, and communication challenges are barriers to change. Developing accountability tools and processes to promote maternal standards of care holds the potential to increase the health and wellbeing of mothers and their babies and improve re-integration into society.

Common Traditions, Practices, and Beliefs Related to Safe Motherhood and Newborn Health in Morocco.

The cultural context influences women's antenatal care and postpartum knowledge. This study aims to determine the traditional practices related to maternal health in Morocco. We conducted in-depth qualitative interviews with 37 women from three different Moroccan regions on the first postpartum day. We used thematic content to analyze data, and an a priori coding framework was created utilizing the pertinent literature. Beliefs regarding pregnancy and postpartum positively affect maternal health, such as family support, prolonged rest for health recovery, and specific dietary precautions according to the mode of delivery of the new mother. However, some practices may negatively affect maternal health, such as cold postpartum treatment through traditional medicine and not seeking prenatal care after the first pregnancy experience. Such practices include painting newborns with henna, using kohl and oil to hasten the umbilical cord's descent, and producing solutions based on chicken throat to cure respiratory ailments in newborns that might harm their health.

Preconception health status and associated disparities among rural, Midwestern women in the United States.

BACKGROUND: Little is known about the preconception/interconception health and behaviors of reproductive-age women in the rural Midwest of the United States. The purpose of this study was to quantify preconception/interconception health status and to identify disparities compared with statewide estimates. METHODS: In this cross-sectional study, we collected data on 12 health conditions and behaviors that are risk factors for adverse maternal and infant health outcomes from nonpregnant women ages 18-45 years in rural northwestern Ohio. Statistical tests were used to identify associations between selected demographic characteristics and a subset of eight high-priority health measures (smoking, diabetes, heavy alcohol use, folic acid intake, normal weight, sufficient physical activity, and effective contraception use); all but physical activity could be compared with Ohio estimates derived from the Behavioral Risk Factor Surveillance System and Ohio Pregnancy Assessment Survey. RESULTS: Three hundred-fifteen women participated, with 98.4% reporting at least one high-priority risk factor. Statistically significant differences were identified among subpopulations related to smoking, folic acid, normal weight, sufficient physical activity, and effective contraception use. In addition, the proportion of participants reporting hypertension (P < 0.001), smoking (P < 0.001), abnormal weight (P = 0.002), and lack of daily folic acid intake (P = 0.006) were statistically significantly higher than expected based on statewide estimates. CONCLUSIONS: Women in the rural Midwest of the United States are at risk for poor health and pregnancy outcomes. Statewide estimates tracking preconception/interconception health status may obscure variation for at-risk groups, particularly in rural or underserved areas. These findings illustrate the need for interventions to advance preconception/interconception health and improve methods to capture and analyze data for rural women.

Prevalence, trend and determinants of adolescent childbearing in Burundi: a multilevel analysis of the 1987 to 2016-17 Burundi Demographic and Health Surveys data.

BACKGROUND: Very little is known about factors influencing adolescent childbearing despite an upward trend in adolescent childbearing prevalence in Burundi, and its perceived implications on the rapid population growth and ill-health of young mothers and their babies. To adress this gap, this study aimed to examine the prevalence, trends and determinants of adolescent childbearing in Burundi. METHODS: Secondary analyses of the 1987, 2010 and 2016-17 Burundi Demographic and Health Surveys (BDHS) data were conducted using STATA. Weighted samples of 731 (1987 BDHS), 2359 (2010 BDHS) and 3859 (2016-17BDHS) adolescent girls aged 15-19 years old were used for descriptive and trend analyses. Both bivariable and multivariable two-level logistic regression analyses were performed to identify the main factors associated with adolescent childbearing using only the 2016-17 BDHS data. RESULTS: The prevalence of adolescent childbearing increased from 5.9% in 1987 to 8.3% in 2016/17. Factors such as adolescent girls aged 18-19 years old (aOR =5.85, 95% CI: 3.54-9.65, p <  0.001), adolescent illiteracy (aOR = 4.18, 95% CI: 1.88-9.30, p <  0.001), living in poor communities (aOR = 2.19, 95% CI: 1.03-4.64, p = 0.042), early marriage (aOR = 9.28, 95% CI: 3.11-27.65, p <  0.001), lack of knowledge of any contraceptive methods (aOR = 5.33, 95% CI: 1.48-19.16, p = 0.010), and non-use of modern contraceptive methods (aOR = 24.48, 95% CI: 9.80-61.14), p <  0.001) were associated with higher odds of adolescent childbearing. While factors such as living in the richest household index (aOR = 0.52, 95% IC: 0.45-0.87, p = 0.00), living in West region (aOR = 0.26, 95%CI: 0.08-0.86, p = 0.027) or in South region (aOR = 0.31, 95% CI: 0.10-0.96, p = 0.041) were associated with lower odds of adolescent childbearing. CONCLUSION: Our study found an upward trend in adolescent childbearing prevalence and there were significant variations in the odds of adolescent childbearing by some individual and community-level factors. School-and community-based intervention programs aimed at promoting girls' education, improving socioeconomic status, knowledge and utilization of contraceptives and prevention of early marriage among adolescent girls is crucial to reduce adolescent childbearing in Burundi.

Routine Healthcare Utilization Among Reproductive-Age Women Residing in a Rural Maternity Care Desert.

It is important that women of reproductive age have access to and use routine health services to improve birth outcomes. While it is estimated that more than 5 million women in over 1000 counties across the United States live in maternity care deserts, to date there have been no published studies characterizing access and barriers to routine healthcare utilization in these areas. Therefore, a cross-sectional study was conducted in a rural county in northwest Ohio with 315 women ages 18-45 years. Health insurance coverage, usual source of care, length of time since routine check-up, and barriers to receipt of health services were assessed via a self-reported, anonymous survey. Over one-tenth (11.3%) of participants reported having no health insurance coverage. A total of 14.4% reported having no usual source of care and 22.8% reported not having a routine check-up in the past year. Just over one-half (53.0%) of participants reported having at least one barrier to accessing health care. In a logistic regression analysis, having a routine check-up in the past year was inversely associated with number of barriers (OR 0.73, 95% CI 0.56-0.95; p = 0.019); women who reported more barriers were less likely to report receipt of preventive care in the past year. The results of this study reveal that many reproductive-age women living in a maternity care desert face challenges in accessing health services. Policies and programs need to be developed and implemented to close these gaps and maximize opportunities for optimal health.

Improved RIDIT statistic approach provides more intuitive and informative interpretation of EQ-5D data.

BACKGROUND: EQ-5D is generic measure of health-related quality of life. Studies using EQ-5D generate ordinal data that are interpreted as categories ordered by severity. New analytic approaches taking into account the ordinal nature of the health dimension severity and leading to a better interpretation of EQ-5D data are needed to better elucidate differences in health-related quality of life. We propose utilizing the Improved RIDIT statistical method to analyze EQ-5D outcomes. METHODS: 556 Moroccan participants aged over 18 years representing four chronic diseases: back pain (n = 158), renal insufficiency (n = 56), diabetes (n = 82) or hypertension (n = 80) and healthy subjects (n = 180). All participants received the two EQ-5D versions. Two other published data sets were included. The first was extracted from a diabetic Spain study and the second was extracted from a clinical trial study. The Improved RIDIT analyses were carried out using an R statistic program we developed. RESULTS: Applying the Improved RIDIT on the EQ-5D data allowed estimating for the first time the ordinal odds, the Absolute Risk Reduction (ARR) or the Absolute Risk Increase (ARI) and the Number Needed to Treat. The ARI values estimated for Moroccan patients showed that (i) hypertension increased anxiety/depression by 66% and reduced mobility by 65%; (ii) back pain increased pain/discomfort by 69%; (iii) renal insufficiency impacts mobility (ARI = 57%, oddsordinal = 9.95) and usual activities (ARI = 44%, oddsordinal = 6.41) and (iv) diabetes acts only on anxiety/depression (ARI = 50%, oddsordinal = 4.8). Also, we demonstrated that the approach works well in clinical trials. CONCLUSIONS: Improved RIDIT provides more intuitive and informative interpretation of the EQ-5D data by (1) taking into account the level severity; estimating (2) the odds ordinal, (3) the ARR/ARI and the NNT; (4) analyzing the five dimensions of the EQ-5D separately, which gives clinical teams more precision in understanding the treatment/pathology impacts on the health status and completes the EQ-5D data analysis based on score utilities.

Krox20/EGR2 deficiency accelerates cell growth and differentiation in the monocytic lineage and decreases bone mass.

Krox20/EGR2, one of the 4 early growth response genes, is a highly conserved transcription factor implicated in hindbrain development, peripheral nerve myelination, tumor suppression, and monocyte/macrophage cell fate determination. Here, we established a novel role for Krox20 in postnatal skeletal metabolism. Microcomputed tomographic analysis of 4- and 8-week-old mice revealed a low bone mass phenotype (LBM) in both the distal femur and the vertebra of Krox20(+/-) mice. This was attributable to accelerated bone resorption as demonstrated in vivo by increased osteoclast number and serum C-terminal telopeptides, a marker for collagen degradation. Krox20 haploinsufficiency did not reduce bone formation in vivo, nor did it compromise osteoblast differentiation in vitro. In contrast, growth and differentiation were significantly stimulated in preosteoclast cultures derived from Krox20(+/-) splenocytes, suggesting that the LBM is attributable to Krox20 haploinsufficiency in the monocytic lineage. Furthermore, Krox20 silencing in preosteoclasts increased cFms expression and response to macrophage colony-stimulating factor, leading to a cell-autonomous stimulation of cell-cycle progression. Our data indicate that the antimitogenic role of Krox20 in preosteoclasts is the predominant mechanism underlying the LBM phenotype of Krox20-deficient mice. Stimulation of Krox20 expression in preosteoclasts may present a viable therapeutic strategy for high-turnover osteoporosis.

Novel indirect calorimetry technology to analyze metabolism in individual neonatal rodent pups.

BACKGROUND: The ability to characterize the development of metabolic function in neonatal rodents has been limited due to technological constraints. Low respiratory volumes and flows at rest pose unique problems, making it difficult to reliably measure O(2) consumption, CO(2) production, respiratory quotient (RQ), and energy expenditure (EE). Our aim was to develop and validate a commercial-grade indirect calorimetry system capable of characterizing the metabolic phenotype of individual neonatal rodents. METHODOLOGY/PRINCIPAL FINDINGS: To address this research need, we developed a novel, highly sensitive open-circuit indirect calorimetry system capable of analyzing respiratory gas exchange in a single neonatal rodent pup. Additionally, we derived an equation from known metabolic relationships to estimate inlet flow rates, improving the efficiency of data collection. To validate the neonatal rodent indirect calorimetry system and evaluate the applicability of the derived equation for predicting appropriate flow rates, we conducted a series of experiments evaluating the impact of sex, litter size, time of day (during the light phase), and ambient temperature on neonatal rat metabolic parameters. Data revealed that the only metabolic parameter influenced by litter size is a neonatal rat's RQ, with rat pups reared in a small litter (5 pups) having lower RQ's than rat pups reared in either medium (8 pups) or large (11 pups) litters. Furthermore, data showed that ambient temperature affected all metabolic parameters measured, with colder temperatures being associated with higher CO(2) production, higher O(2) consumption, and higher energy expenditure. CONCLUSION/SIGNIFICANCE: The results of this study demonstrate that the modified Panlab Oxylet system reliably assesses early postnatal metabolism in individual neonatal rodents. This system will be of paramount importance to further our understanding of processes associated with the developmental origins of adult metabolic disease.

Growth deficits in a postnatal day 3 rat model of hypoxic-ischemic brain injury.

The postnatal day (P) 3 rat model of hypoxic-ischemic (HI) brain injury provides valuable information regarding the cellular response to HI injury in a very immature brain. Our present study is the first to examine growth, metabolic, and behavioral outcomes following a P3 HI brain injury. Rats were injured by cauterizing the right common carotid, and exposure to 8% oxygen for 1.5h. Control rats received sham surgery and exposure to 1.5h of room air. One cohort of rats was examined for growth patterns through P33, evaluated using a battery of tests focused on early postnatal feeding behaviors, and studied using the open field paradigm during the early postnatal and postweaning periods. Another cohort of rats was used to examine metabolic parameters using indirect calorimetry. Significant growth deficits emerged in injured rats during the second postnatal week. No significant differences between groups were noted in the expression of feeding-related behaviors or in metabolic parameters between groups. However, we did observe significant associations between feeding-related behaviors and P14 growth parameters in injured rats. In the open field assessment, HI rats showed increased circling and supination behaviors only during the early postnatal period. Our data reveal that P3 HI brain injury results in generalized growth deficits that persist through postweaning. Analyses suggest that alterations in feeding-related behaviors contribute to growth deficits following a P3 HI brain injury.

The development of mastication in rodents: from neurons to behaviors.

The development of suckling behavior is a fundamental characteristic of mammalian development. The occurrence of this behavior across mammals allows us to extrapolate information from animal models to better understand normal and abnormal masticatory development in infants. This review focuses on prenatal cell, molecular, and morphological changes in rat and/or mouse masticatory muscles, trigeminal motoneurons (Mo5) and mesencephalic trigeminal neurons (Me5) that accompany the development of suckling behavior. A special emphasis is placed on N-methyl-d-aspartate (NMDA) receptor subunit expression because of the important role that NMDA receptors play in the production of rhythmical jaw movements and neuronal development. Prenatally the timing of NMDA subunit changes follows neuromuscular junction formation in masticatory muscles, and is coincident with the emergence of rhythmical jaw movements and in vitro rhythmical trigeminal activity. Our data suggest that NMDA receptor subunit changes in Mo5 and Me5 are synchronized with the emergence of rhythmical jaw movements and trigeminal motor activity.

NR3 protein expression in trigeminal neurons during postnatal development.

The N-methyl-d-aspartate (NMDA) receptor plays an important role in the generation of rhythmical oral motor activities. To compliment our previous studies, we examined the developmental regulation of NR3A and NR3B expression in trigeminal motoneurons (Mo5) and mesencephalic trigeminal neurons (Me5). NR3A-immunoreactive neurons were observed at all ages in both nuclei, decreasing in Mo5 and caudal Me5 after P14, and increasing in rostral Me5. NR3B protein expression only emerged in Mo5 after P21-23. Results indicate that NR3A and NR3B expression is differentially regulated between Mo5 and Me5 coincident with the transition from suckling to chewing.

Mesencephalic trigeminal nucleus development is dependent on Krox-20 expression.

Krox-20, a C2H2-type zinc-finger transcription factor, plays an important role in rhombomere development. This study reveals that the Krox-20 null mutation impacts the development of mesencephalic trigeminal (Me5) neurons, a cell group traditionally thought to emerge from the mesencephalon. Based on cell counting studies, we show that Krox-20 null mutants have twice as many Me5 neurons relative to wildtypes at E15, but by birth have half the number of Me5 cells as wildtypes. TUNEL studies reveal a period of increased apoptosis from E17-P0 in mutants. The mutation does not result in differences in Me5 cell size, morphology, gene expression or peripheral projection patterns between genotypes, as demonstrated by retrograde tracing and Brn3a immunohistochemistry. The data suggest that Krox-20 regulates the period and extent of Me5 apoptosis, impacting the final number of Me5 neurons. The loss of Me5 in Krox-20-/- mice may highlight species-specific differences in the origin of these cells.

Krox-20 gene expression: influencing hindbrain-craniofacial developmental interactions.

Krox-20 is a C(2)H(2)-type zinc-finger transcription factor that plays an essential role in hindbrain development. The Krox-20 null mutation results in hindbrain anomalies that result in neonatal death due to respiratory and feeding deficits. Here we review our studies of how the Krox- 20 null mutation impacts the development of motor and sensory systems critical for the production of consummatory behaviors (suckling/chewing). First, we demonstrated that Krox-20 null mutants suffer a selective loss of primary jaw-opening muscles during prenatal development. In vivo and in vitro studies are reviewed that highlight intrinsic defects in mutant jaw-opener muscles that contribute to muscle degeneration. Next we focus on the impact of the mutation on proprioceptive neurons activated during consummatory behaviors. Mesencephalic trigeminal (Me5) neurons are primary sensory neurons that relay jaw proprioception to the central nervous system. These cells are unique because their cell bodies are located in the central as opposed to the peripheral nervous system. Data are reviewed that demonstrate the impact of the mutation on Me5 neurons, a cell group traditionally thought to emerge from the mesencephalon. We show that Krox-20 null mutants have twice as many Me5 neurons relative to wildtypes at E15, but by birth have half the number of Me5 cells as wildtypes. TUNEL assays performed in each set of studies reveal that Krox-20 expression acts to protect both muscle and mesencephalic trigeminal neurons against apoptosis, suggesting that Krox-20, in addition to its role in hindbrain patterning, has a broader, long-lasting role in development.

Prenatal development of NMDA receptor composition and function in trigeminal neurons.

The prenatal development of neural circuits for rhythmical oral-motor behaviors used for feeding is essential for the survival of the newborn mammal. The N-methyl-D-aspartate (NMDA) receptor plays a critical role in brainstem circuits underlying postnatal oral-motor behaviors. To understand a role for the NMDA receptor in the emergence of sucking behavior we conducted physiological and immunohistochemical experiments using fetal rats. Physiology experiments examined the development of the NMDA dose response of the brainstem circuit responsible for generating rhythmical trigeminal activity by recording trigeminal motor outputs using an in vitro preparation. The high dose of NMDA agonist bath application affected the mean cycle duration of rhythmical trigeminal activity (RTA) at both embryonic day (E) 18-19 and E20-21 in comparison with standard concentration of NMDA agonist. NMDA receptor immunohistochemistry studies, using antibodies directed against subunits NR1, NR2A, NR2B, NR3A and NR3B were performed to determine the prenatal regulation of NMDA subunits in trigeminal motoneurons (Mo5), and mesencephalic trigeminal neurons (Me5) between E17 to E20. In Mo5, NR1, NR2A, NR2B and NR3A immunoreactivity was observed throughout the time frame sampled. NR3B immunoreactivity was not observed in Mo5 or Me5. In Mo5, there was a significant decrease in the percentage of NR2B immunoreactive neurons between E17 and E20, and a concurrent increase in the NR2A/NR2B ratio between E17 and E20. In Me5, NR1, NR2A and NR3A immunoreactivity was observed throughout the time frame sampled; a significant decrease in the percentage of NR2A immunoreactive neurons between E17 and E20, and NR3A immunoreactive neurons between E17 and E18 occurred. The timing of subunit changes between E17 and E18 is coincident with the prenatal emergence of rhythmical jaw movements, and in vitro rhythmical trigeminal activity, shown in earlier studies. Our data suggest that NMDA receptor plays an important role in the development and function of prenatal oral-motor circuits.