Neurobehavioral and neurochemical effects of perinatal arsenite exposure in Sprague-Dawley rats.

Exposure to relatively high levels of inorganic arsenic (iAs) is associated with detrimental effects on human health, including cancer and diabetes. The effects of lower-level exposures are less clear, and gaps in the literature exist as to the effects of iAs exposure on neurodevelopment. The current study assessed the effects of perinatal iAs exposure on rodent neurodevelopment and behavior. Pregnant Sprague-Dawley (SD) rats were exposed to arsenite (AsIII) via oral gavage on gestational days (GD) 6 through 21, and pups were directly dosed via gavage on postnatal days (PND) 1 through 21. Dams and offspring received the same doses: 0.00, 0.10, 1.50, or 3.75 mg/kg/day. Male and female offspring underwent a battery of behavioral assessments from weaning until PND 180. Brain arsenic levels increased in a dose-dependent manner at both PND 1 and 21. Results from the behavioral tests show that pre- and postnatal AsIII exposure did not adversely affect offspring weight gain, adolescent motor and cognitive functions, or adult motor and cognitive functions in the SD rat. There were no differences in concentration of several brain proteins associated with blood-brain barrier permeability, dopamine functions, and inflammation.

Tauroursodeoxycholic acid (TUDCA) is neuroprotective in a chronic mouse model of Parkinson's disease.

OBJECTIVE: Parkinson's disease (PD) is a progressive motor disease of unknown etiology. Although neuroprotective ability of endogenous bile acid, tauroursodeoxycholic acid (TUDCA), shown in various diseases, including an acute model of PD,the potential therapeutic role of TUDCA in progressive models of PD that exhibit all aspects of PD has not been elucidated. In the present study, mice were assigned to one of four treatment groups: (1) Probenecid (PROB); (2) TUDCA, (3) MPTP + PROB (MPTPp); and (3) TUDCA + MPTPp. Methods: Markers for dopaminergic function, neuroinflammation, oxidative stress and autophagy were assessed using high performance liquid chromatography (HPLC), immunohistochemistry (IHC) and western blot (WB) methods. Locomotion was measured before and after treatments. Results: MPTPp decreased the expression of dopamine transporters (DAT) and tyrosine hydroxylase (TH), indicating dopaminergic damage, and induced microglial and astroglial activation as demonstrated by IHC analysis. MPTPp also decreased DA and its metabolites as demonstrated by HPLC analysis. Further, MPTPp-induced protein oxidation; increased LAMP-1 expression indicated autophagy and the promotion of alpha-synuclein (α-SYN) aggregation. Discussion: Pretreatment with TUDCA protected against dopaminergic neuronal damage, prevented the microglial and astroglial activation, as well as the DA and DOPAC reductions caused by MPTPp. TUDCA by itself did not produce any significant change, with data similar to the negative control group. Pretreatment with TUDCA prevented protein oxidation and autophagy, in addition to inhibiting α-SYN aggregation. Although TUDCA pretreatment did not significantly affect locomotion, only acute treatment effects were measured, indicating more extensive assessments may be necessary to reveal potential therapeutic effects on behavior. Together, these results suggest that autophagy may be involved in the progression of PD and that TUDCA may attenuate these effects. The efficacy of TUDCA as a novel therapy in patients with PD clearly warrants further study.

Alzheimer's disease: a step closer to understanding type 3 diabetes in African Americans.

Alzheimer's disease (AD) is the fourth leading cause of death in the United States and the most common cause of adult-onset dementia. Recent results suggest an increased prevalence and severity in African Americans compared to Caucasians. Our understanding of the potential mechanism(s) underlying this ethnicity difference is limited. We previously described ethnicity-related differences in levels of neurodegenerative proteins and cytokines/chemokines in the BA21 region of African Americans and Caucasians with AD. Here, similar multiplex assays were used to examine those endpoints in patient postmortem cerebrospinal fluid (CSF). Additionally, we measured levels of C-peptide, ghrelin, gastric inhibitory polypeptide (GIP), glucagon-like peptide-1 (GLP-1), glucagon, insulin, leptin, PAI-1, resistin, and visfatin using a human diabetes 10-plex assay. The cytokine and chemokine assays revealed that levels of 26 chemokines or cytokines differed significantly with ethnicity, and three of those were significantly associated with gender. The neurodegenerative disease panel indicated that levels of soluble RAGE were significantly elevated in African Americans compared to Caucasians. All measures in the diabetes disease panel assay were significantly elevated in African Americans: ghrelin, GIP, GLP-1, glucagon, insulin, and visfatin. Through peripheral sample analysis, these results provide further evidence that ethnicity is critically involved in the manifestation of AD.

Minimal effects from a single exposure to sevoflurane in adult male and female Sprague-Dawley rats.

Many people undergo procedures requiring general anesthesia each day and adverse cognitive effects have been reported in response to that anesthesia. Postoperative Cognitive Dysfunction (POCD) may occur in as many as 80% of adults during the first post-surgical week and can have lasting effects. Here, the cognitive and motor effects of sevoflurane exposure in Sprague-Dawley rats was examined along with body weights, blood oxygen saturation, heart rate, and body temperature. Male and female rats were exposed to 2.5% sevoflurane or medical grade air for one hour at postnatal day 115. Beginning the following day, rats began a series of behavioral tests examining locomotor activity, motor coordination, novel object recognition, and spatial learning and memory in a water maze. Blood oxygen saturation, heart rate, and body temperature were not affected by the sevoflurane exposure. A slight effect on locomotor activity was detected, but no effects on motor coordination, novel object recognition, or spatial learning and memory were observed. Brain weights following behavioral testing did not differ. The results reported here along with existing literature suggest sevoflurane is largely without effects on later cognition in adult rodents when exposure is of a relatively short duration and at a relatively low concentration.

Acetyl-l-carnitine does not prevent neurodegeneration in a rodent model of prolonged neonatal anesthesia.

Many studies have shown that prolonged or repeated use of general anesthesia early in life can cause an increase in neurodegeneration and lasting changes in behavior. While short periods of general anesthesia appear to be safe, there is a concern about the neurotoxic potential of prolonged or repeated general anesthesia in young children. Unfortunately, the use of general anesthesia in children cannot be avoided. It would be a great benefit to develop a strategy to reduce or reverse anesthesia mitigated neurotoxicity. The mechanisms behind anesthesia related neurotoxicity are unknown, but evidence suggests that mitochondrial dysfunction and abnormal energy utilization are involved. Recent research suggests that a class of compounds known as carnitines may be effective at preventing anesthesia related neurotoxicity by influencing fatty acid metabolism in the mitochondria. However, it is unknown if carnitines can provide protection against changes in behavior associated with early life exposure to anesthesia. Accordingly, we evaluated the neuroprotective potential of acetyl-l-carnitine in 7-day old rats. Rat pups were exposed to 6 h of general anesthesia with sevoflurane or a control condition, with and without acetyl-l-carnitine. The oxygenation level of animals was continuously monitored during sevoflurane exposure, and any animal showing signs of hypoxia was removed from the study. Animals exposed to sevoflurane showed clear signs of neurodegeneration 2 h after sevoflurane exposure. The hippocampus, cortex, thalamus, and caudate putamen all had elevated levels of Fluoro-Jade C staining. Despite the elevated levels of Fluoro-Jade C, few behavioral changes were observed in an independent cohort of animals treated with sevoflurane. Furthermore, acetyl-l-carnitine had little impact on levels of Fluoro-Jade C staining in animals treated with sevoflurane. These data suggest that acetyl-l-carnitine may offer little protection again anesthesia related neurotoxicity in fully oxygenated animals.

Increased inflammation in BA21 brain tissue from African Americans with Alzheimer's disease.

Chronic neuroinflammation is strongly associated with AD and altered peripheral and central levels of chemokines and cytokines have been frequently described in those with AD. Given the increasing evidence of ethnicity-related differences in AD, it was of interest to determine if those altered chemokine and cytokine levels are ethnicity-related. Because African Americans exhibit a higher incidence of AD and increased symptom severity, we explored chemokine and cytokine concentrations in post-mortem brain tissue from the BA21 region of African Americans and Caucasians with AD using multiplex assays. IL-1ß, MIG, TRAIL, and FADD levels were significantly increased in African Americans while levels of IL-3 and IL-8 were significantly decreased. Those effects did not interact with gender; however, overall levels of CCL25, CCL26 and CX3CL1 were significantly decreased in women. The NLRP3 inflammasome is thought to be critically involved in AD. Increased activation of this inflammasome in African Americans is consistent with the current results.

Developmental neurotoxicity of inorganic arsenic exposure in Sprague-Dawley rats.

High levels of inorganic arsenic (iAs) exposure are associated with severe health effects. Less clear are effects of lower exposure levels on neurodevelopment. Relative to maternal intake, there is limited lactational transfer of arsenic in humans or rodents, yet there are few rodent studies which directly exposed preweaning animals. To more clearly determine iAs developmental neurotoxicity, 28 pregnant Sprague-Dawley rats were exposed to arsenate (AsV) via drinking water (0, 23.6, 47.7, 71.0 ppm) (n = 5-7/group) from gestational day (GD) 6 through GD 22 with targeted doses of 0, 2.33, 4.67, 7.00 mg/kg/day, respectively. Offspring were dosed by gavage daily with the same mg/kg AsV dose as intended for their dam from postnatal day (PND) 1 to 21. Gestational water intake was reduced at all AsV doses, but returned to control levels on lactational day (LD) 1 when control water was returned. Gestational body weight was reduced only at the highest dose on GD 22 and lactational body weight was unaffected. Food intake was unaffected. iAs exposure did not alter offspring body weight (PNDs 1-21) or age at fur development and bilateral ear opening. Incisor eruption, however, was significantly delayed in offspring of the 4.67 and 7.00 mg/kg groups. Further, all iAs groups were significantly delayed in bilateral eye opening. Righting reflex (PNDs 3-6) was unaffected, while slant board performance (PNDs 8-11) was significantly poorer at the highest dose. Brains of culled pups (PND 1) showed dose-dependent increases of iAs. There were no significant AsV-related effects on PND 21 brain regional concentrations of dopamine, DOPAC, HVA, 5-HT or 5-HIAA. These hazard identification results will guide the study designs of developmental iAs exposure at human-relevant levels essential for risk-assessment.

Effects of Cyclophosphamide and/or Doxorubicin in a Murine Model of Postchemotherapy Cognitive Impairment.

Postchemotherapy cognitive impairment, or PCCI, is a common complaint, particularly among breast cancer patients. However, the exact nature of PCCI appears complex. To model the human condition, ovariectomized C57BL/6J mice were treated intravenous weekly for 4 weeks with saline, 2 mg/kg doxorubicin (DOX), 50 mg/kg cyclophosphamide (CYP), or DOX + CYP. For the subsequent 10 weeks, mice were assessed on several behavioral tests, including those measuring spatial learning and memory. After sacrifice, hippocampal spine density and morphology in the dentate gyrus, CA1, and CA3 regions were measured. Additionally, hippocampal levels of total glutathione, glutathione disulfide, MnSOD, CuZnSOD, and cytokines were measured. Body weight decreased in all groups during treatment, but recovered post-treatment. Most behaviors were unaffected by drug treatment: Open field activity, motor coordination, grip strength, water maze and Barnes maze performance, buried food test performance, and novel object and object location recognition tests. There were some significant effects of CYP and DOX + CYP treatment during the initial test of home cage behavior, but these did not persist into the second and third test times. Density of stubby spines, but not mushroom or thin spines, in the dentate gyrus was significantly decreased in the DOX, CYP, and DOX + CYP treatment groups. There were no significant effects in the CA1 or CA3 regions. CuZnSOD levels were significantly increased in DOX + CYP-treated mice; other hippocampal antioxidant levels were unaffected. Most cytokines showed no treatment-related effects, but IL-1ß, IL-6, and IL-12 were slightly reduced in mice treated with DOX + CYP. Although the animal model, route of exposure, and DOX and CYP doses used here were reflective of human exposure, there were only sporadic effects due to chemotherapeutic treatment.

A Working Module for the Neurovascular Unit in the Sexually Dimorphic Nucleus of the Preoptic Area.

The neurovascular unit (NVU) can be conceptualized as a functional entity consisting of neurons, astrocytes, pericytes, and endothelial and smooth muscle cells that operate in concert to affect blood flow to a very circumscribed area. Although we are currently in a "golden era" of bioengineering, there are, as yet, no living NVUs-on-a-chip modules available and the development of a neural chip that would mimic NVUs is a seemingly lofty goal. The sexually dimorphic nucleus of the preoptic area (SDN-POA) is a tiny brain structure (between 0.001~0.007 mm3 in rats) with an assessable biological function (i.e., male sexual behavior). The present effort was undertaken to determine whether there are identifiable NVUs in the SDN-POA by assessing its vasculature relative to its known neural components. First, a thorough and systematic review of thousands of histologic and immunofluorescent images from 201 weanling and adult rats was undertaken to define the characteristics of the vessels supplying the SDN-POA: its primary supply artery/arteriole and capillaries are physically inseparable from their neural elements. A subsequent immunofluorescent study targeting α-smooth muscle actin confirmed the identity of an artery/arteriole supplying the SDN-POA. In reality, the predominant components of the SDN-POA are calbindin D28k-positive neurons that are comingled with tyrosine hydroxylase-positive projections. Finally, a schematic of an SDN-POA NVU is proposed as a working model of the basic building block of the CNS. Such modules could serve the study of neurovascular mechanisms and potentially inform the development of next generation bioengineered neural transplants, i.e., the construct of an NVU neural chip.

Neurodegenerative Markers are Increased in Postmortem BA21 Tissue from African Americans with Alzheimer's Disease.

BACKGROUND: Alzheimer's disease (AD) presents with an earlier onset age and increased symptom severity in African Americans and Hispanics. OBJECTIVE: Although the prevalence of plaques and tangles may not exhibit ethnicity-related differences, levels of neurodegenerative proteins have not been described. METHODS: Here, levels of five proteins (i.e., S100B, sRAGE, GDNF, Aß40, and Aß42) and the Aß42/Aß40 ratio were measured in postmortem samples of the middle temporal gyrus (BA21) from age-matched African Americans and Caucasians with AD (n = 6/gender/ethnicity). RESULTS: S100B levels were increased 17% in African Americans (p < 0.003) while sRAGE was mildly decreased (p < 0.09). Aß42 levels were increased 121% in African Americans (p < 0.02), leading to a 493% increase in the Aß42/Aß40 ratio (p < 0.002). Analysis of GDNF levels did not indicate any significant effects. There were no significant effects of gender and no significant ethnicity with gender interactions on any analyte. Effect size calculations indicated "medium" to "very large" effects. CONCLUSION: S100B is typically elevated in AD cases; however, the increased levels in African Americans here may be indicative of increased severity in specific populations. Increased Aß42/Aß40 ratios in the current study are compatible with increased disease severity and might indicate increased AD pathogenesis in African Americans. Overall, these results are compatible with a hypothesis of increased neuroinflammation in African Americans with AD.

Effects of developmental exposure to bisphenol A on spatial navigational learning and memory in rats: A CLARITY-BPA study.

Bisphenol A (BPA) is a ubiquitous industrial chemical used in the production of a wide variety of items. Previous studies suggest BPA exposure may result in neuro-disruptive effects; however, data are inconsistent across animal and human studies. As part of the Consortium Linking Academic and Regulatory Insights on BPA Toxicity (CLARITY-BPA), we sought to determine whether female and male rats developmentally exposed to BPA demonstrated later spatial navigational learning and memory deficits. Pregnant NCTR Sprague-Dawley rats were orally dosed from gestational day 6 to parturition, and offspring were directly orally dosed until weaning (postnatal day 21). Treatment groups included a vehicle control, three BPA doses (2.5µg/kg body weight (bw)/day-[2.5], 25µg/kg bw/day-[25], and 2500µg/kg bw/day-[2500]) and a 0.5µg/kg/day ethinyl estradiol (EE)-reference estrogen dose. At adulthood, 1/sex/litter was tested for seven days in the Barnes maze. The 2500 BPA group sniffed more incorrect holes on day 7 than those in the control, 2.5 BPA, and EE groups. The 2500 BPA females were less likely than control females to locate the escape box in the allotted time (p value=0.04). Although 2.5 BPA females exhibited a prolonged latency, the effect did not reach significance (p value=0.06), whereas 2.5 BPA males showed improved latency compared to control males (p value=0.04), although the significance of this result is uncertain. No differences in serum testosterone concentration were detected in any male or female treatment groups. Current findings suggest developmental exposure of rats to BPA may disrupt aspects of spatial navigational learning and memory.

NIEHS/FDA CLARITY-BPA research program update.

Bisphenol A (BPA) is a chemical used in the production of numerous consumer products resulting in potential daily human exposure to this chemical. The FDA previously evaluated the body of BPA toxicology data and determined that BPA is safe at current exposure levels. Although consistent with the assessment of some other regulatory agencies around the world, this determination of BPA safety continues to be debated in scientific and popular publications, resulting in conflicting messages to the public. Thus, the National Toxicology Program (NTP), National Institute of Environmental Health Sciences (NIEHS), and U.S. Food and Drug Administration (FDA) developed a consortium-based research program to link more effectively a variety of hypothesis-based research investigations and guideline-compliant safety testing with BPA. This collaboration is known as the Consortium Linking Academic and Regulatory Insights on BPA Toxicity (CLARITY-BPA). This paper provides a detailed description of the conduct of the study and a midterm update on progress of the CLARITY-BPA research program.

Pre- and postnatal bisphenol A treatment does not alter the number of tyrosine hydroxylase-positive cells in the anteroventral periventricular nucleus (AVPV) of weanling male and female rats.

Exposure to Bisphenol A (BPA) may interfere with brain sexual differentiation. Altered numbers of tyrosine hydroxylase (TH) cells in the rodent anteroventral periventricular nucleus (AVPV) after developmental BPA treatment have been reported; however, definitive conclusions are lacking. The current study incorporated many of the guidelines suggested for endocrine disrupter research. Specifically, ethinyl estradiol (EE2) served as a reference estrogen, exogenous environmental estrogen exposure was controlled, BPA was administered orally, and subjects consumed a low phytoestrogen diet. Here, on gestational days 6-21, Sprague-Dawley rats (10-15/group) were gavaged with 2.5 or 25.0 µg BPA/kg/day or 5.0 or 10.0 µg EE2/kg/day or the vehicle (5 ml of 0.3% aqueous carboxymethylcellulose/kg/day). A naïve control group was weighed and restrained, but not gavaged. Beginning on postnatal day (PND) 1 and continuing until PND 21, the 4 pups/sex/litter were orally treated with the same dose their dam had received. On PND 21, 1/sex/litter was perfused and the brain removed. TH immunoreactivity (TH-ir) was counted in 8 images/pup by a technician blind to treatment status. ANOVA results indicated significantly higher TH-ir cells/mm(2) in females (main effect of sex: p<0.01); however, there was no significant effect of treatment or a significant interaction of treatment with sex. In a separate untreated group of PND 21 Sprague-Dawley pups, AVPV volume was quantified and no significant sexual dimorphism was apparent. Similar to our reported results of behavioral assessments, the BPA treatment paradigm used here (2.5 or 25.0 µg BPA/kg/day administered orally) does not appear to cause significant alterations in AVPV TH-ir.

Estrogen Selectively Mobilizes Neural Stem Cells in the Third Ventricle Stem Cell Niche of Postnatal Day 21 Rats.

The neuroprotective properties of stem cells have been described for various pathophysiological states. Here, we determined the effects of exogenous perinatal estrogen treatment on endogenous neural stem cell activity in the third ventricle stem cell niche (3VSCN) and the caudal third ventricle (C3V). Pregnant Sprague-Dawley rats were gavaged with ethinyl estradiol (EE2, 10 µg/kg/day) or vehicle on gestational days 6-21, and their offspring were similarly treated from birth to weaning on postnatal day 21. At weaning, neural stem cell activity was investigated using the stem cell markers nestin, Ki-67, phosphohistone H3 (PHH3), and doublecortin (DCX). The 3VSCN was characterized by nestin labeling, but little DCX labeling, while both the subventricular (SVZ) and subgranular zones (SGZ) displayed robust DCX expression. Ki-67 cell counts in the 3VSCN were 2.2 to 6.4 times those of the C3V. In the 3VSCN, EE2 treatment significantly increased Ki-67, PHH3, and co-labeled cell counts by 135-207 %, effects which appeared stronger in females. EE2 treatment had only marginally significant effects in the C3V, mildly increasing PHH3 and co-labeled cell counts. Perinatal estrogen treatment selectively increased and mobilized proliferative cells in the 3VSCN at weaning, potentially providing increased neuroprotection. Because PHH3 cells are thought to be in the mitotic phase of the cell cycle and Ki-67 cells can be found in most phases of the cycle, the effect of estrogen treatment on 3VSCN cells appears to involve enhancement of mitosis.

Chronic MPTP treatment produces hyperactivity in male mice which is not alleviated by concurrent trehalose treatment.

The chronic MPTP+probenecid treatment paradigm has been used to successfully model the neurochemical, neuropathological, and behavioral effects associated with Parkinson's disease. Here, adult male C57Bl/6 mice were injected ip with 25 mg/kg MPTP and 250 mg/kg probenecid (MPTPp) or saline twice weekly for a total of 10 injections. Behavioral assessments included motor coordination, grip strength, spatial learning/memory, locomotor activity, and anhedonia. Those assessments were repeated up to 8 weeks post-treatment. In a subsequent experiment, adult male mice were treated with saline or MPTPp as described above. One-half of each group was allowed access to 1% trehalose in the water bottle. Trehalose intake averaged 1.90-2.34 g/kg. Behavioral assessments included locomotor activity, olfaction, motor coordination, grip strength, and exploratory behavior. Those assessments were repeated 4 weeks post-treatment. The strongest MPTPp effect was hyperactivity as exhibited in the open field. This increased activity was apparent in both experiments and occurred at all time points post-treatment. Assessments of grip strength, water maze performance, olfaction, and exploratory behavior did not indicate MPTPp-related alterations. When the specifications for the motor coordination test were made somewhat easier in the second experiment, there were deficits exhibited by the MPTPp group, the MPTPp+trehalose group and the trehalose group. The addition of trehalose did not alleviate any of the MPTPp-induced behavioral alterations; however, trehalose treatment significantly attenuated the striatal decreases in DA, DOPAC, HVA and 5-HIAA. These results provide a more comprehensive description of the behavioral alterations resulting from the chronic MPTPp treatment regimen and suggest that trehalose at this concentration does not act as a complete neuroprotectant.

Effects of perinatal methylphenidate (MPH) treatment on postweaning behaviors of male and female Sprague-Dawley rats.

Methylphenidate (MPH) is a common treatment for adult Attention Deficit Hyperactivity Disorder (ADHD). However, little information exists regarding its safety during pregnancy and thus, women with ADHD face difficult decisions regarding continued use during pregnancy. Thus, Sprague-Dawley rats were orally treated 3×/day with 0 (control), 6 (low), 18 (mid), or 42 (high) mg MPH/kg/day (i.e., 0, 2, 6, or 14mg/kg at each treatment time) on gestational days 6-21. All offspring/litter were orally treated with the same dose their dam had received on postnatal days (PNDs) 1-21. After weaning, offspring were assessed for adolescent play behavior, locomotor activity, motor coordination, Barnes maze performance, acoustic startle response, novel object recognition, residential running wheel activity, flavored solution intake, home cage behavior, water maze performance, elevated plus maze behavior, locomotor response to an MPH challenge, and passive avoidance. At euthanasia, whole brain and striatal weights as well as serum hormone levels were measured. Body weights of the high MPH group were reduced in both sexes. Males of the high MPH group were less active than control males in open field assessments on PNDs 40-42. Latency to maximum acoustic startle was significantly altered in females of the medium and high MPH groups and residential running wheel activity of females of the low and medium MPH groups was lower than control females. Open arm entries in the elevated plus maze were increased in subjects of the medium MPH group. Females of the low MPH group were less sensitive to the locomotor-increasing effects of an acute 5mg/kg MPH challenge. Serum hormone levels and whole brain and striatal weights were not altered by prior MPH treatment. These results indicate that MPH treatment during development has sporadic effects on postweaning behaviors and those effects were generally exhibited by females.

Effects of adolescent treatment with nicotine, harmane, or norharmane in male Sprague-Dawley rats.

The initiation of tobacco use occurs most often in adolescence and may be especially detrimental as the adolescent brain is undergoing substantial development. In addition to nicotine, there are over 9000 other compounds present in tobacco products, including the ß-carbolines harmane and norharmane. The present study aimed to determine the long-term effects of adolescent exposure to nicotine (NIC), harmane (HAR), or norharmane (NOR) on locomotor activity, learning and memory, anxiety-like behavior, motor coordination, and monoamine/metabolite concentrations in the striatum and nucleus accumbens of male Sprague-Dawley rats. Beginning on postnatal day (PND) 27 and continuing through PND 55, subjects received twice daily intraperitoneal injections of 1ml/kg saline (CON), 0.5mg NIC/kg, 0.5mg HAR/kg, or 0.5mg NOR/kg. Body weight, food, and water intake were measured daily (PNDs 27-96). Locomotor activity was assessed on PND 40 or 41, PND 55, and PNDs 81 and 82. Other behaviors (anxiety-like behavior, motor coordination, and spatial learning and memory) were assessed at least 25 days after drug exposure ended (PNDs 80-91). On PND 97, subjects were decapitated and the striatum and nucleus accumbens were dissected and frozen for analysis. NIC treatment significantly decreased food intake, but did not alter locomotor activity during or after treatment. HAR and NOR treatment, however, caused significant open field hypoactivity. Motor coordination, water maze performance, and concentrations of monoamines and metabolites in the striatum and nucleus accumbens were unaltered by any drug treatment. These results indicate a long-lasting effect on activity levels from adolescent HAR or NOR treatment; however, there were few long-lasting NIC effects. Given the paucity of data describing effects of HAR or NOR exposure, these data should encourage additional studies of these tobacco constituents as well as constituent combination studies.

Effects of developmental methylphenidate (MPH) treatment on monoamine neurochemistry of male and female rats.

Attention Deficit Hyperactivity Disorder (ADHD) is estimated to affect 4-5% of the adult human population (Kessler et al., 2006; Willcutt, 2012). Often prescribed to attenuate ADHD symptoms (Nair and Moss, 2009), methylphenidate hydrochloride (MPH) can have substantial positive effects. However, there is a paucity of literature regarding its use during pregnancy. Thus, adult women with ADHD face a difficult decision when contemplating pregnancy. In this study, pregnant Sprague-Dawley rats were orally treated a total of 0 (water), 6 (low), 18 (medium), or 42 (high) mg MPH/kg body weight/day (divided into three doses) on gestational days 6-21 (i.e., the low dose received 2 mg MPH/kg body weight 3×/day). Offspring were orally treated with the same daily dose as their dam (divided into two doses) on postnatal days (PNDs) 1-21. One offspring/sex/litter was sacrificed at PND 22 or PND 104 (n=6-7/age/sex/treatment group) and the striatum was quickly dissected and frozen. High Performance Liquid Chromatography (HPLC) coupled to a Photo Diode Array detector (PDA) was used to analyze monoamine content in the striatum of one side while a sandwich ELISA was used to analyze tyrosine hydroxylase (TH) from the other side. Age significantly affected monoamine and metabolite content as well as turnover ratios (i.e., DA, DOPAC, HVA, DOPAC/DA, HVA/DA, 5-HT and 5-HIAA); however, there were no significant effects of sex. Adult rats of the low MPH group had higher DA levels than control adults (p<0.05). At both ages, subjects of the low MPH group had higher TH levels than controls (p<0.05), although neither effect (i.e., higher DA or TH levels) exhibited an apparent dose-response. PND 22 subjects of the high MPH treatment group had higher ratios of HVA/DA and DOPAC/DA than same-age control subjects (p<0.05). The increased TH levels of the low MPH group may be related to the increased DA levels of adult rats. While developmental MPH treatment appears to have some effects on monoamine system development, further studies are required to determine if these alterations manifest as functional changes in behavior.

Developmental treatment with ethinyl estradiol, but not bisphenol A, causes alterations in sexually dimorphic behaviors in male and female Sprague Dawley rats.

The developing central nervous system may be particularly sensitive to bisphenol A (BPA)-induced alterations. Here, pregnant Sprague Dawley rats (n = 11-12/group) were gavaged daily with vehicle, 2.5 or 25.0 µg/kg BPA, or 5.0 or 10.0 µg/kg ethinyl estradiol (EE2) on gestational days 6-21. The BPA doses were selected to be below the no-observed-adverse-effect level (NOAEL) of 5 mg/kg/day. On postnatal days 1-21, all offspring/litter were orally treated with the same dose. A naïve control group was not gavaged. Body weight, pubertal age, estrous cyclicity, and adult serum hormone levels were measured. Adolescent play, running wheel activity, flavored solution intake, female sex behavior, and manually elicited lordosis were assessed. No significant differences existed between the vehicle and naïve control groups. Vehicle controls exhibited significant sexual dimorphism for most behaviors, indicating these evaluations were sensitive to sex differences. However, only EE2 treatment caused significant effects. Relative to female controls, EE2-treated females were heavier, exhibited delayed vaginal opening, aberrant estrous cyclicity, increased play behavior, decreased running wheel activity, and increased aggression toward the stimulus male during sexual behavior assessments. Relative to male controls, EE2-treated males were older at testes descent and preputial separation and had lower testosterone levels. These results suggest EE2-induced masculinization/defeminization of females and are consistent with increased volume of the sexually dimorphic nucleus of the preoptic area (SDN-POA) at weaning in female siblings of these subjects (He, Z., Paule, M. G. and Ferguson, S. A. (2012) Low oral doses of bisphenol A increase volume of the sexually dimorphic nucleus of the preoptic area in male, but not female, rats at postnatal day 21. Neurotoxicol. Teratol. 34, 331-337). Although EE2 treatment caused pubertal delays and decreased testosterone levels in males, their behaviors were within the range of control males. Conversely, BPA treatment did not alter any measured endpoint. Similar to our previous reports (Ferguson, S. A., Law, C. D. Jr and Abshire, J. S. (2011) Developmental treatment with bisphenol A or ethinyl estradiol causes few alterations on early preweaning measures. Toxicol. Sci. 124, 149-160; Ferguson, S. A., Law, C. D. and Abshire, J. S. (2012) Developmental treatment with bisphenol A causes few alterations on measures of postweaning activity and learning. Neurotoxicol. Teratol. 34, 598-606), the BPA doses and design used here produced few alterations.

Barnes maze testing strategies with small and large rodent models.

Spatial learning and memory of laboratory rodents is often assessed via navigational ability in mazes, most popular of which are the water and dry-land (Barnes) mazes. Improved performance over sessions or trials is thought to reflect learning and memory of the escape cage/platform location. Considered less stressful than water mazes, the Barnes maze is a relatively simple design of a circular platform top with several holes equally spaced around the perimeter edge. All but one of the holes are false-bottomed or blind-ending, while one leads to an escape cage. Mildly aversive stimuli (e.g. bright overhead lights) provide motivation to locate the escape cage. Latency to locate the escape cage can be measured during the session; however, additional endpoints typically require video recording. From those video recordings, use of automated tracking software can generate a variety of endpoints that are similar to those produced in water mazes (e.g. distance traveled, velocity/speed, time spent in the correct quadrant, time spent moving/resting, and confirmation of latency). Type of search strategy (i.e. random, serial, or direct) can be categorized as well. Barnes maze construction and testing methodologies can differ for small rodents, such as mice, and large rodents, such as rats. For example, while extra-maze cues are effective for rats, smaller wild rodents may require intra-maze cues with a visual barrier around the maze. Appropriate stimuli must be identified which motivate the rodent to locate the escape cage. Both Barnes and water mazes can be time consuming as 4-7 test trials are typically required to detect improved learning and memory performance (e.g. shorter latencies or path lengths to locate the escape platform or cage) and/or differences between experimental groups. Even so, the Barnes maze is a widely employed behavioral assessment measuring spatial navigational abilities and their potential disruption by genetic, neurobehavioral manipulations, or drug/ toxicant exposure.