Are Prerequisite Courses Barriers to Pharmacy Admission or the Keys to Student Success?

The variability and complexity of course prerequisites across colleges and schools of pharmacy can result in barriers to admission. While prerequisites play an important role in the admissions process and assuring student preparation, requiring excessive prerequisites can create unnecessary challenges for applicants. Prospective students may choose not to apply to a particular pharmacy school or even enter the profession because they cannot complete all course prerequisites in time to apply. Extraneous prerequisites can also contribute to the cost of education and educational indebtedness, which can more adversely affect minority and disadvantaged students. Pharmacy programs should carefully examine their course prerequisite requirements and consider new ways to measure preparedness to attract a diverse and competent pool of applicants to the profession while also being more competitive with other health professions programs.

Mood-stabilizing effects of rapamycin and its analog temsirolimus: relevance to autophagy.

Accumulated data support a relationship between mood disorders and cellular plasticity and resilience, some suggesting relevance to autophagy. Our previous data show that pharmacological enhancement of autophagy results in antidepressant-like effects in mice. The current study was designed to further examine the effects of autophagy enhancement on mood by testing the effects of subchronic treatment with the mammalian target of rapamycin (mTOR) inhibitors and autophagy enhancers rapamycin and temsirolimus in a model for mania and in a model for antidepressant action, respectively. The results show that rapamycin reduced mania-like aggression and reward-seeking behaviors, with no effects on locomotion. Temsirolimus reduced depression-related immobility in the forced-swim test without effects on locomotion in the open field or on anxiety-related measures in the elevated plus maze. Taken together with our previous findings, these data support the notion that enhancing autophagy may have mood-stabilizing effects.

Fetal and neonatal iron deficiency but not copper deficiency increases vascular complexity in the developing rat brain.

OBJECTIVES: Anemia caused by nutritional deficiencies, such as iron and copper deficiencies, is a global health problem. Iron and copper deficiencies have their most profound effect on the developing fetus/infant, leading to brain development deficits and poor cognitive outcomes. Tissue iron depletion or chronic anemia can induce cellular hypoxic signaling. In mice, chronic hypoxia induces a compensatory increase in brain blood vessel outgrowth. We hypothesized that developmental anemia, due to iron or copper deficiencies, induces angiogenesis/vasculogenesis in the neonatal brain. METHODS: To test our hypothesis, three independent experiments were performed where pregnant rats were fed iron- or copper-deficient diets from gestational day 2 through mid-lactation. Effects on the neonatal brain vasculature were determined using quantitative real-time polymerase chain reaction to assess mRNA levels of angiogenesis/vasculogenesis-associated genes and GLUT1 immunohistochemistry to assess brain blood vessel density and complexity. RESULTS: Iron deficiency, but not copper deficiency, increased mRNA expression of brain endothelial cell- and angiogenesis/vasculogenesis-associated genes (i.e. Glut1, Vwf, Vegfa, Ang2, Cxcl12, and Flk1) in the neonatal brain, suggesting increased cerebrovascular density. Iron deficiency also increased hippocampal and cerebral cortical blood vessel branching by 62 and 78%, respectively. DISCUSSION: This study demonstrates increased blood vessel complexity in the neonatal iron-deficient brain, which is likely due to elevated angiogenic/vasculogenic signaling. At least initially, this is probably an adaptive response to maintain metabolic substrate homeostasis in the developing iron-deficient brain. However, this may also contribute to long-term neurodevelopmental deficits.

Opioid prescribing patterns for non-malignant chronic pain for rural versus non-rural US adults: a population-based study using 2010 NAMCS data.

BACKGROUND: Non-malignant chronic pain (NMCP) is one of the most common reasons for primary care visits. Pain management health care disparities have been documented in relation to patient gender, race, and socioeconomic status. Although not studied in relation to chronic pain management, studies have found that living in a rural community in the US is associated with health care disparities. Rurality as a social determinant of health may influence opioid prescribing. We examined rural and non-rural differences in opioid prescribing patterns for NMCP management, hypothesizing that distinct from education, income, racial or gender differences, rural residency is a significant and independent factor in opioid prescribing patterns. METHODS: 2010 National Ambulatory Medical Care Survey (NAMCS) data were examined using bivariate and multivariate techniques. NAMCS data were collected using a multi-stage sampling strategy. For the multivariate analysis performed the SPSS complex samples algorithm for logistic regression was used. RESULTS: In 2010 an estimated 9,325,603 US adults (weighted from a sample of 2745) seen in primary care clinics had a diagnosis of NMCP; 36.4% were prescribed an opioid. For US adults with a NMCP diagnosis bivariate analysis revealed rural residents had higher odds of having an opioid prescription than similar non-rural adults (OR = 1.515, 95% CI 1.513-1.518). Complex samples logistic regression analysis confirmed the importance of rurality and yielded that US adults with NMCP who were prescribed an opioid had higher odds of: being non-Caucasian (AOR =2.459, 95% CI 1.194-5.066), and living in a rural area (AOR =2.935, 95% CI 1.416-6.083). CONCLUSIONS: Our results clearly indicated that rurality is an important factor in opioid prescribing patterns that cannot be ignored and bears further investigation. Further research on the growing concern about the over-prescribing of opioids in the US should now include rurality as a variable in data generation and analysis. Future research should also attempt to document the ecological, sociological and political factors impacting opioid prescribing and care in rural communities. Prescribers and health care policy makers need to critically evaluate the implications of our findings and their relationship to patient needs, best practices in a rural setting, and the overall consequences of increased opioid prescribing on rural communities.

Fetal and neonatal iron deficiency exacerbates mild thyroid hormone insufficiency effects on male thyroid hormone levels and brain thyroid hormone-responsive gene expression.

Fetal/neonatal iron (Fe) and iodine/TH deficiencies lead to similar brain developmental abnormalities and often coexist in developing countries. We recently demonstrated that fetal/neonatal Fe deficiency results in a mild neonatal thyroidal impairment, suggesting that TH insufficiency contributes to the neurodevelopmental abnormalities associated with Fe deficiency. We hypothesized that combining Fe deficiency with an additional mild thyroidal perturbation (6-propyl-2-thiouracil [PTU]) during development would more severely impair neonatal thyroidal status and brain TH-responsive gene expression than either deficiency alone. Early gestation pregnant rats were assigned to 7 different treatment groups: control, Fe deficient (FeD), mild TH deficient (1 ppm PTU), moderate TH deficient (3 ppm PTU), severe TH deficient (10 ppm PTU), FeD/1 ppm PTU, or FeD/3 ppm PTU. FeD or 1 ppm PTU treatment alone reduced postnatal day 15 serum total T4 concentrations by 64% and 74%, respectively, without significantly altering serum total T3 concentrations. Neither treatment alone significantly altered postnatal day 16 cortical or hippocampal T3 concentrations. FeD combined with 1 ppm PTU treatment produced a more severe effect, reducing serum total T4 by 95%, and lowering hippocampal and cortical T3 concentrations by 24% and 31%, respectively. Combined FeD/PTU had a more severe effect on brain TH-responsive gene expression than either treatment alone, significantly altering Pvalb, Dio2, Mbp, and Hairless hippocampal and/or cortical mRNA levels. FeD/PTU treatment more severely impacted cortical and hippocampal parvalbumin protein expression compared with either individual treatment. These data suggest that combining 2 mild thyroidal insults during development significantly disrupts thyroid function and impairs TH-regulated brain gene expression.

Fetal and neonatal iron deficiency reduces thyroid hormone-responsive gene mRNA levels in the neonatal rat hippocampus and cerebral cortex.

Copper (Cu), iron (Fe), and thyroid hormone (TH) deficiencies produce similar defects in late brain development including hypomyelination of axons and impaired synapse formation and function, suggesting that these micronutrient deficiencies share a common mechanism contributing to these derangements. We previously demonstrated that fetal/neonatal Cu and Fe deficiencies lower circulating TH concentrations in neonatal rats. Fe deficiency also reduces whole-brain T(3) content, suggesting impaired TH action in the developing Fe-deficient brain. We hypothesized that fetal/neonatal Cu and Fe deficiencies will produce mild or moderate TH deficiencies and will impair TH-responsive gene expression in the neonatal cerebral cortex and hippocampus. To test this hypothesis, we rendered pregnant Sprague Dawley rats Cu-, Fe-, or TH-deficient from early gestation through postnatal d 10 (P10). Mild and moderate TH deficiencies were induced by 1 and 3 ppm propylthiouracil treatment, respectively. Cu deficiency did not significantly alter serum or tissue TH concentrations or TH-responsive brain mRNA expression. Fe deficiency significantly lowered P10 serum total T(3) (45%), serum total T(4) (52%), whole brain T(3) (14%), and hippocampal T(3) (18%) concentrations, producing a mild TH deficiency similar to 1 ppm propylthiouracil treatment. Fe deficiency lowered Pvalb, Enpp6, and Mbp mRNA levels in the P10 hippocampus. Fe deficiency also altered Hairless, Dbm, and Dio2 mRNA levels in the P10 cerebral cortex. These results suggest that some of the brain defects associated with Fe deficiency may be mediated through altered thyroidal status and the concomitant alterations in TH-responsive gene transcription.

Modeling mania: Further validation for Black Swiss mice as model animals.

The paucity of appropriate animal models for bipolar disorder hinders the research of the disorder and its treatments. Previous work suggests that Black Swiss (BS) mice may be a suitable model animal for behavioral domains of mania including reward-seeking, risk-taking, vigor, aggression and sensitivity to psychostimulants. These behaviors are high in BS mice compared with other strains and are responsive to the mood stabilizers lithium and valproate but not to the antidepressant imipramine. The current study evaluated the etiological validity of this model by assessing brain expression of two proteins implicated in affective disorders, ß-catenin and BDNF, in BS mice versus C57bl/6, A/J and CBA/J mice. Additionally, pharmacological validity was further tested by assessing the effects of risperidone in a behavioral battery of tests. ß-catenin and BDNF expression were evaluated in the frontal cortex and hippocampus of untreated BS, CBA/J, A/J and C57bl/6 mice by western blot. Subchronic 0.1 and 0.3mg/kg doses of risperidone were tested in a battery of behavioral tests for domains of mania. Expression of ß-catenin was found to be lower in the hippocampus of BS mice compared with the other strains. Reduced ß-catenin expression was not observed in the frontal cortex. BDNF expression levels were similar between strains in both the hippocampus and frontal cortex. In the behavioral tests, risperidone ameliorated amphetamine-induced hyperactivity without affecting other tests in the battery. These results offer additional pharmacological and possible etiological validity supporting the utilization of Black Swiss mice as a model for domains of mania.

Maternal iron supplementation attenuates the impact of perinatal copper deficiency but does not eliminate hypotriiodothyroninemia nor impaired sensorimotor development.

Copper, iron and iodine/thyroid hormone (TH) deficiencies disrupt brain development. Neonatal Cu deficiency causes Fe deficiency and may impact thyroidal status. One purpose of these studies was to determine the impact of improved iron status following Cu deficiency by supplementing the diet with iron. Cu deficiency was produced in pregnant Holtzman [Experiment 1 (Exp. 1)] or Sprague-Dawley [Experiment 2 (Exp. 2)] rats using two different diets. In Exp. 2, dietary Fe content was increased from 35 to 75 mg/kg according to NRC guidelines for reproduction. Cu-deficient (CuD) Postnatal Day 24 (P24) rats from both experiments demonstrated lower hemoglobin, serum Fe and serum triiodothyronine (T3) concentrations. However, brain Fe was lower only in CuD P24 rats in Exp. 1. Hemoglobin and serum Fe were higher in Cu adequate (CuA) P24 rats from Exp. 2 compared to Exp. 1. Cu- and TH-deficient rats from Exp. 2 exhibited a similar sensorimotor functional deficit following 3 months of repletion. Results suggest that Cu deficiency may impact TH status independent of its impact on iron biology. Further research is needed to clarify the individual roles for Cu, Fe and TH in brain development.

Evidence of evolutionary conservation of function between the thyroxine transporter Oatp1c1 and major facilitator superfamily members.

Organic anion transporting polypeptide 1c1 (Oatp1c1) is a high-affinity T(4) transporter expressed in brain barrier cells. To identify Oatp1c1 amino acid residues critical for T(4) transport, consensus membrane topology was predicted and a three-dimensional Oatp1c1 structure was generated using the known structures of major facilitator superfamily (MFS) transporters, glycerol 3-phosphate transporter, lactose permease, and the multidrug transporter Escherichia coli multidrug resistance protein D as templates. A total of nine amino acid mutations were generated based on amino acid conservation, localization to putative transmembrane domains, and side chain functionality. Mutant constructs were transiently transfected into human embryonic kidney 293 cells and assessed for plasma membrane localization and the capacity to transport substrate (125)I-T(4). Wild-type Oatp1c1, R601S, P609A, W277A/W278A, W277F/W278F, G399A/G409A, and G399L/G409L were all expressed at the plasma membrane. Wild-type Oatp1c1 and W277F/W278F displayed biphasic T(4) transport kinetics, albeit the mutant did so with an approximately 10-fold increase in high-affinity Michaelis constant. The W277A/W278A mutation abolished Oatp1c1 T(4) transport. G399A/G409A and G399V/G409V mutants displayed near wild-type activity in an uptake screen but exhibited diminished T(4) transport activity at high-substrate concentrations, suggesting a substrate binding site collapse or inability to convert between input and output states. Finally, transmembrane domain 11 mutants R601S and P609A displayed partial T(4) transport activity with significantly reduced maximum velocities and higher Michaelis constant. Arg601 is functionally strongly conserved with members of the MFS whose structures and function have been extensively studied. These data provide the experimental foundation for mapping Oatp1c1 substrate binding sites and reveal evolutionary conservation with bacterial MFS transporter members.

Perinatal iron and copper deficiencies alter neonatal rat circulating and brain thyroid hormone concentrations.

Copper (Cu), iron (Fe), and iodine/thyroid hormone (TH) deficiencies lead to similar defects in late brain development, suggesting that these micronutrient deficiencies share a common mechanism contributing to the observed derangements. Previous studies in rodents (postweanling and adult) and humans (adolescent and adult) indicate that Cu and Fe deficiencies affect the hypothalamic-pituitary-thyroid axis, leading to altered TH status. Importantly, however, relationships between Fe and Cu deficiencies and thyroidal status have not been assessed in the most vulnerable population, the developing fetus/neonate. We hypothesized that Cu and Fe deficiencies reduce circulating and brain TH levels during development, contributing to the defects in brain development associated with these deficiencies. To test this hypothesis, pregnant rat dams were rendered Cu deficient (CuD), FeD, or TH deficient from early gestation through weaning. Serum thyroxine (T(4)) and triiodothyronine (T(3)), and brain T(3) levels, were subsequently measured in postnatal d 12 (P12) pups. Cu deficiency reduced serum total T(3) by 48%, serum total T(4) by 21%, and whole-brain T(3) by 10% at P12. Fe deficiency reduced serum total T(3) by 43%, serum total T(4) by 67%, and whole-brain T(3) by 25% at P12. Brain mRNA analysis revealed that expression of several TH-responsive genes were altered in CuD or FeD neonates, suggesting that reduced TH concentrations were sensed by the FeD and CuD neonatal brain. These results indicate that at least some of the brain defects associated with neonatal Fe and Cu deficiencies are mediated through reductions in circulating and brain TH levels.

Characterization of thyroid hormone transporter expression during tissue-specific metamorphic events in Xenopus tropicalis.

Thyroid hormone (TH) induces the dramatic morphological and physiological changes that together comprise amphibian metamorphosis. TH-responsive tissues vary widely with developmental timing of TH-induced changes. How larval tadpole tissues are able to employ distinct metamorphic programs in a developmental stage- and TH-dependent manner is still unknown. Recently, several proteins capable of transporting TH have been identified. TH action and metabolism occurs primarily intracellularly, highlighting the importance of TH transporters. We examined the hypothesis that TH transporter expression and tissue distribution play an important role in mediating TH-induced metamorphic events. Xenopus tropicalis homologs for known TH transporting OATP, MCT and LAT family proteins were identified and gene specific qRT-PCR primers were developed. Total RNA was extracted from tissues representing three unique developmental fates including: growth/differentiation (hind limb), death/resorption (gill, tail) and remodeling (brain, liver, kidney). For growing and resorbing tissues, results showed the general trend of low initial expression levels of MCT8 and MCT10 transporters, followed by a several-fold increase of expression as the tissue undergoes TH-dependent metamorphic changes. The expression pattern in remodeling tissues was less uniform: a general decrease in transporter expression was observed in the liver, while the kidney and brain exhibited a range of expression patterns for several TH transporters. Collectively, these developmental expression patterns are consistent with TH transporting proteins playing a role in the effects of TH in peripheral tissues.

The blood-brain barrier thyroxine transporter organic anion-transporting polypeptide 1c1 displays atypical transport kinetics.

Organic anion-transporting polypeptide (Oatp) 1c1 is a high-affinity T(4) transporter expressed in brain barrier cells. Oatp1c1 transports a variety of additional ligands including the conjugated sterol estradiol 17beta-glucuronide (E(2)17betaG). Intriguingly, published data suggest that E(2)17betaG inhibition of Oatp1c1-mediated T(4) transport exhibits characteristics suggestive of atypical transport kinetics. To determine whether Oatp1c1 exhibits atypical transport kinetics, we first performed detailed T(4) and E(2)17betaG uptake assays using Oatp1c1 stably transfected HEK293 cells and a wide range of T(4) and E(2)17betaG concentrations (100 pm to 300 nm and 27 nm to 200 mum, respectively). Eadie-Hofstee plots derived from these detailed T(4) and E(2)17betaG uptake experiments display a biphasic profile consistent with atypical transport kinetics. These data along with T(4) and E(2)17betaG cis-inhibition dose-response measurements revealed shared high- and low-affinity Oatp1c1 binding sites for T(4) and E(2)17betaG. T(4) and E(2)17betaG recognized these Oatp1c1 binding sites with opposite preferences. In addition, sterols glucuronidated in the 17 or 21 position, exhibited preferential substrate-dependent inhibition of Oatp1c1 transport, inhibiting Oatp1c1-mediated E(2)17betaG transport more strongly than T(4) transport. Together these data reveal that Oatp1c1-dependent substrate transport is a complex process involving substrate interaction with multiple binding sites and competition for binding with a variety of other substrates. A thorough understanding of atypical Oatp1c1 transport processes and substrate-dependent inhibition will allow better prediction of endo- and xenobiotic interactions with the Oatp transporter.

The Thrsp null mouse (Thrsp(tm1cnm)) and diet-induced obesity.

We created a Thrsp (Spot 14 or S14) null mouse (Thrsp(tm1cnm)) to study the role of Thrsp in de novo lipid synthesis. The Thrsp null mouse exhibits marked deficiencies in de novo lipogenesis in the lactating mammary gland. We now report the Thrsp gene deletion affects body weight and glucose tolerance associated with increased insulin sensitivity. By post-natal day 150 the rate of first generation C57BL/6J backcross Thrsp null mouse weight gain slowed compared to wild type animals. This was due to changes in body fat mass. We studied mice backcrossed for 5 and 11 generations. The weight difference between the null and wild type adult mice diminished with progressive backcross generations. In conclusion the Thrsp gene is involved in the regulation of diet-induced obesity and deletion of Thrsp leads to an improvement in age associated glucose tolerance.

Competitive inhibition of organic anion transporting polypeptide 1c1-mediated thyroxine transport by the fenamate class of nonsteroidal antiinflammatory drugs.

Organic anion transporting polypeptide (Oatp) 1c1 is a high-affinity T(4) transporter with narrow substrate specificity expressed at the blood-brain barrier. A transport model using cells overexpressing Oatp1c1 was created to identify novel Oatp1c1 substrates and inhibitors. Rat Oatp1c1 was cloned and stably expressed in human embryonic kidney 293 cells. Oatp1c1-transfected human embryonic kidney 293 cells transported (125)I-labeled T(4) in a time-dependent manner that was completely abolished in the presence of excess unlabeled T(4). Next, various compounds, including inhibitors of thyroid hormone uptake, were screened for inhibitory effects on Oatp1c1-mediated T(4) uptake. Phenytoin (64%), indocyanine green (17%), fenamic acid (68%), diclofenac (51%), and meclofenamic acid (33%) all reduced T(4) uptake by Oatp1c1 when assayed at concentrations of 10 microM. Dose-response assays for the fenamic acids, iopanoic acid, indocyanine green, and phenytoin revealed IC(50) values for Oatp1c1 T(4) uptake below or near the blood plasma levels after therapeutic doses. Further kinetic assays and reciprocal plot analyses demonstrated that the fenamic acid diclofenac inhibited in a competitive manner. Finally, microvessels were isolated from adult rat brain and assessed for T(4) uptake. Ten micromolar of fenamate concentrations inhibited T(4) microvessel uptake with a similar hierarchical inhibition profile [fenamic acid (43%), diclofenac (78%), and meclofenamic acid (85%)], as observed for Oatp1c1 transfected cells. Oatp1c1 is expressed luminally and abluminally in the blood-brain barrier endothelial cell, and exhibits bidirectional transport capabilities. Together, these data suggest that Oatp1c1 transports fenamates into, and perhaps across, brain barrier cells.

Novel and emerging strategies in drug delivery for overcoming the blood-brain barrier.

Two decades of molecular research have revealed the presence of transporters and receptors expressed in the brain vascular endothelium that provide potential novel targets for the rational design of blood-brain barrier-penetrating drugs. In this review, we briefly introduce the reader to the molecular characteristics of the blood-brain barrier that make this one of the most important obstacles towards the development of efficacious CNS drugs. We highlight recent attempts to rationally target influx and bidirectional transport systems expressed on the brain endothelial cell and avoid the important obstacle presented in the form of efflux transporters. Many of these approaches are highly innovative and show promise for future human application. Some of these approaches, however, have revealed significant limitations and are critiqued in this review. Nonetheless, these combined efforts have left the field of CNS drug delivery better positioned for developing novel approaches towards the rational design of CNS-penetrating drugs.

Hepatic expression of the SPOT 14 (S14) paralog S14-related (Mid1 interacting protein) is regulated by dietary carbohydrate.

The Spot 14 (S14) gene is rapidly up-regulated by signals that induce lipogenesis such as enhanced glucose metabolism and thyroid hormone administration. Previous studies in S14 null mice show that S14 is required for normal lipogenesis in the lactating mammary gland, but not the liver. We speculated that the lack of a hepatic phenotype was due to the expression of a compensatory gene. We recently reported that this gene is likely an S14 paralog that we named S14-Related (S14-R). S14-R is expressed in the liver, but not in the mammary gland. If S14-R compensates for the absence of S14 in the liver, we hypothesized that, like S14, S14-R expression should be glucose responsive. Here, we report that hepatic S14-R mRNA levels increase with high-carbohydrate feeding in mice or within 2 h of treating cultured hepatocytes with elevated glucose. A potential carbohydrate response element (ChoRE) was identified at position -458 of the S14-R promoter. Deletion of or point mutations within the putative S14-R ChoRE led to 50-95% inhibition of the glucose response. Gel-shift analysis revealed that the glucose-activated transcription complex carbohydrate responsive element-binding protein/Max-like protein X (Mlx) binds to the S14-R ChoRE. Finally, S14-R glucose induction is completely blocked when a dominant-negative form of Mlx is overexpressed in primary hepatocytes. In conclusion, our results indicate that the S14-R gene is a glucose-responsive target of carbohydrate responsive element-binding protein/Mlx and suggest that the S14-R protein is a compensatory factor, at least partially responsible for the normal liver lipogenesis observed in the S14 null mouse.

Thyroid hormone and cerebellar development.

Thyroid hormone (TH) plays a key role in mammalian brain development. The developing brain is sensitive to both TH deficiency and excess. Brain development in the absence of TH results in motor skill deficiencies and reduced intellectual development. These functional abnormalities can be attributed to maldevelopment of specific cell types and regions of the brain including the cerebellum. TH functions at the molecular level by regulating gene transcription. Therefore, understanding how TH regulates cerebellar development requires identification of TH-regulated gene targets and the cells expressing these genes. Additionally, the process of TH-dependent regulation of gene expression is tightly controlled by mechanisms including regulation of TH transport, TH metabolism, toxicologic inhibition of TH signaling, and control of the nuclear TH response apparatus. This review will describe the functional, cellular, and molecular effects of TH deficit in the developing cerebellum and emphasize the most recent findings regarding TH action in this important brain region.

Organic anion-transporting polypeptides at the blood-brain and blood-cerebrospinal fluid barriers.

Organic anion-transporting polypeptides (Oatps) are solute carrier family members that exhibit marked evolutionary conservation. Mammalian Oatps exhibit wide tissue expression with an emphasis on expression in barrier cells. In the brain, Oatps are expressed in the blood-brain barrier endothelial cells and blood-cerebrospinal fluid barrier epithelial cells. This expression profile serves to illustrate a central role for Oatps in transporting endo- and xenobiotics across brain barrier cells. This chapter will detail the expression patterns and substrate specificities of Oatps expressed in the brain, and will place special emphases on the role of Oatps in prostaglandin synthesis and in the transport of conjugated endobiotics.

The Spot 14 protein is required for de novo lipid synthesis in the lactating mammary gland.

We generated a Spot 14 null mouse to assess the role of Spot 14 in de novo lipid synthesis and report the Spot 14 null mouse exhibits a phenotype in the lactating mammary gland. Spot 14 null pups nursed by Spot 14 null dams gain significantly less weight than wild-type pups nursed by wild-type dams. In contrast, Spot 14 null pups nursed by heterozygous dams show similar weight gain to wild-type littermates. We found the triglyceride content in Spot 14 null milk is significantly reduced. We demonstrate this reduction is the direct result of decreased de novo lipid synthesis in lactating mammary glands, corroborated by a marked reduction of medium-chain fatty acids in the triglyceride pool. Importantly, the reduced lipogenic rate is not associated with significant changes in the activities or mRNA of key lipogenic enzymes. Finally, we report the expression of a Spot 14-related gene in liver and adipose tissue, which is absent in the lactating mammary gland. We suggest that expression of both the Spot 14 and Spot 14-related proteins is required for maximum efficiency of de novo lipid synthesis in vivo and that these proteins impart a novel mechanism regulating de novo lipogenesis.

Thyroid hormone regulates oligodendrocyte accumulation in developing rat brain white matter tracts.

Thyroid hormone (TH) is necessary for normal axonal myelination. Myelin basic protein (MBP) is a structural protein essential for myelin function. In this study, we demonstrate that perinatal hypothyroidism regulates MBP mRNA levels via indirect mechanisms. We observed decreased MBP mRNA accumulation in the hypothyroid rat brain at postnatal (PN) d 10 and 50. Acute TH replacement did not rescue hypothyroid MBP mRNA levels at PN5, 10, or 50. TH is necessary for normal intrahemispheric commissure development including the anterior commissure (AC) and the corpus callosum (CC). We determined that perinatal hypothyroidism decreases AC area and cellularity in the developing rat brain by PN10 and 50. In the developing CC, hypothyroidism initially increases area and cellularity by PN5, but then ultimately decreases area and cellularity by PN50. MBP-expressing oligodendrocytes are a recognized target of TH and are responsible for myelination within intrahemispheric commissures. We found that hypothyroidism reduces the number of mature oligodendrocytes within both the AC and CC. This reduction is noted at PN5, 10, and 50 in the AC and by PN10 and 50 in the CC. Together, these data suggest that TH regulates MBP mRNA levels through indirect mechanisms. These data demonstrate the complex mechanisms whereby TH regulates myelination in the developing brain.