Perinatal lead exposure alters locomotion induced by amphetamine analogs in rats.

Aims: The precise neurochemical perturbations through which perinatal (gestation/lactation) lead exposure modifies the reinforcement efficacy of various psychoactive drugs (e.g., cocaine, opiates) are unknown.

Intracranial magnetic resonance imaging artifacts and pseudolesions in dogs and cats.

Normal anatomic variation, study design, external factors, and tissue characteristics can all influence the manifestation of structures on magnetic resonance images (MRI). For the purpose of this review, imaging artifacts are considered to be nonpathologic abnormalities resulting from study design, intrinsic tissue characteristics, or external factors, while MRI pseudolesions are due to normal anatomic variation. Awareness of imaging artifacts and pseudolesions, as well as normal anatomic structures, is important when determining pathologic vs.

Imaging diagnosis--magnetic resonance imaging pseudolesion associated with the petrous temporal bone.

Normal anatomic variation in the amount of fat within the petrous temporal bone of dogs can result in a magnetic resonance (MR) imaging pseudolesion. Focal hyperintense areas in the region of the hippocampus on T1-weighted, T1-weighted, and fluid-attenuated inversion recovery imaging sequences were noted in a dog being imaged for seizure activity. Further investigation of this region, aided by the use of cadaveric specimens, led to the identification of normal anatomic variability in the amount of fat in the substantia spongiosa of the petrous temporal bone.

Prenatal lead exposure enhances methamphetamine sensitization in rats.

Adult female rats were exposed to lead-free sodium acetate via gavage [0 mg (vehicle control)] or to 16 mg lead as lead acetate for 30 days prior to breeding. Following confirmation of breeding, the female animals continued to be exposed to their respective doses throughout gestation and lactation. When weaned, 16 control and 16 lead-exposed offspring were placed on regular water and food (lead-exposure was discontinued) until postnatal day (PND) 70.

Inorganic nutrients and contaminants in subsistence species of Alaska: linking wildlife and human health.

Objectives: To determine inorganic nutrient and contaminant concentrations in subsistence foods consumed by Alaska Natives, concentration changes related to common preparation methods and provide a basic risk-benefit analysis for these foods.

Study Design: Eleven essential and six non-essential elements were measured in foods derived from spotted seals and sheefish.

Methods: Essential nutrients in foodstuffs were compared to Daily Recommended Intake (DRI) criteria.

Heavy metal and mineral concentrations and their relationship to histopathological findings in the bowhead whale (Balaena mysticetus).

The bowhead whale (Balaena mysticetus) is a species endangered over much of its range that is of great cultural significance and subsistence value to the Inuit of Northern Alaska. This species occupies subarctic and arctic regions presently undergoing significant ecological change and hydrocarbon development. Thus, understanding the health status of the Bering-Chukchi-Beaufort Sea (BCBS) stock of bowhead whales is of importance.

Developmental lead exposure attenuates methamphetamine dose-effect self-administration performance and progressive ratio responding in the male rat.

Perinatal (gestation/lactation) lead exposure modifies the reinforcement efficacy of various psychoactive drugs (e.g., cocaine, opiates) across the phases of initial selection, use, and abuse [Nation J.

Developmental lead exposure alters methamphetamine self-administration in the male rat: acquisition and reinstatement.

The rate of acquisition of drug self-administration and the return to drug seeking are important elements of the overall drug profile, and are essential factors in understanding risks associated with drug abuse. Experiment 1 examined the effects of perinatal (gestation/lactation) lead exposure on adult rates of acquisition of intravenous (i.v.

Total mercury body burden in Pacific harbor seal, Phoca vitulina richardii, pups from central California.

To determine body and tissue compartment-specific burdens (mg) of total mercury (THg), tissues were weighed and analyzed for THg concentration (microg/g fw) in Pacific harbor seal (Phoca vitulina richardii) pups from central California in 2006. THg concentrations were related as follows: hair >> liver = kidney = pelt > muscle > other = heart > brain > blubber > bone. THg burden, however, was related as: pelt = muscle > liver = other > kidney = blubber > brain = heart > bone.

Gross and microscopic findings and investigation of the aetiopathogenesis of mycobacteriosis in a captive population of white-winged ducks (Cairina scutulata).

The white-winged duck (Cairina scutulata) is critically endangered. Breeding collections of this duck are established in the United Kingdom and the USA. Infection with Mycobacterium avium avium serotype 1 is a major cause of mortality in the UK collection.

Essential and non-essential elements in eight tissue types from subsistence-hunted bowhead whale: nutritional and toxicological assessment.

Objectives: To assess essential/non-essential elements in bowhead whale.

Study Design: Analyzes of tissues for key elements and comparing them to published food guidelines.

Methods: Using national and international guidelines calculate percent (%) "Recommended Daily Allowance" of essential elements in 100 g portion of bowhead tissues.

Stable isotope and trace element status of subsistence-hunted bowhead and beluga whales in Alaska and gray whales in Chukotka.

Tissues of bowhead, beluga, and gray whales were analyzed for Ag, Cd, Cu, Se, Zn, THg and MeHg (belugas only). Delta15N and delta13C in muscle were used to estimate trophic position and feeding habitat, respectively. Trace element concentrations in tissues were significantly different among whale species.

IGF-1 administration to prepubertal female rats can overcome delayed puberty caused by maternal Pb exposure.

Because prepubertal female rats maternally exposed to lead (Pb) exhibit suppressed serum levels of insulin-like growth factor-1 (IGF-1) and delayed puberty, we investigated the ability of centrally administered IGF-1 to stimulate luteinizing hormone (LH) release in vivo and LH-releasing hormone (LHRH) release in vitro from maternally Pb-exposed prepubertal female rats. Additionally, we assessed whether IGF-1 replacement could affect the timing of female puberty. Results demonstrated that IGF-1 stimulated significantly LH release in both control and Pb-exposed animals.

Enhanced acquisition of cocaine self-administration in rats developmentally exposed to lead.

The rate of acquisition of drug self-administration may serve as a predictor of later drug-taking behavior, possibly influencing the vulnerability to use drugs. The present study examined the effects of perinatal (gestation/lactation) lead exposure on adult rates of acquisition of intravenous cocaine self-administration using an automated procedure that included both Pavlovian and operant components. For Experiment 1, female rats were gavaged daily with 0 or 16 mg lead for 30 days prior to breeding with nonexposed males.

The effects of the GABAA antagonist bicuculline on cocaine self-administration in rats exposed to lead during gestation/lactation.

The present investigation examined the effects of perinatal lead exposure on cocaine self-administration following a GABAA antagonist pretreatment. Female rats were exposed to either 0 or 16 mg lead daily for 30 days prior to breeding with unexposed males. Beginning on postnatal day (PND) 75, control (N=10) and lead-exposed (N=8) animals were trained to self-administer 0.

Exposure to cadmium during gestation and lactation decreases cocaine self-administration in rats.

This investigation examined the effects of perinatal cadmium exposure on subsequent self-administration of cocaine during the adult cycle. Female Sprague-Dawley rats were gavaged daily with 0.0 (14% sucrose solution, w/v) or 5.

Toxicological evaluation and metal bioavailability in pregnant rats following exposure to clay minerals in the diet.

Silicate clays are frequently added to animal feeds to bind and reduce the bioavailability of mycotoxins in the gastrointestinal tract. However, the bioavailability of trace metals in these clay feed additives has not been thoroughly investigated. Clays that act nonselectively may interact with nutrients, minerals, and other feedborne chemicals to pose significant hidden risks.

Self-administration of heroin in rats: effects of low-level lead exposure during gestation and lactation.

Rationale: Developmental lead exposure has been found to produce differential patterns of drug self-administration in adult animals.

Objectives: The present study examined the effects of perinatal (gestation/lactation) lead exposure on adult patterns of heroin self-administration.

Methods: Female rats were gavaged daily with 0 mg or 16 mg lead for 30 days prior to breeding with non-exposed males.

Early developmental lead exposure increases sensitivity to cocaine in a self-administration paradigm.

The purpose of this investigation was to determine if lead exposure during pregnancy and nursing alters cocaine sensitivity later in the adult cycle, although lead exposure had been discontinued following early development. Female rats were exposed via gavage to 0 or 16 mg/kg lead daily for 30 days prior to breeding with nonexposed males. The respective daily exposure regimens continued throughout gestation and lactation (perinatal lead exposure).

Low level lead (Pb) exposure during gestation and lactation: assessment of effects on pubertal development in Fisher 344 and Sprague-Dawley female rats.

Studies using both Fisher 344 and Sprague-Dawley (SD) rat lines have shown that gestational and/or lactational maternal lead (Pb) exposure causes delayed reproductive maturation in their respective female offspring. Because these studies utilized different experimental regimens for dosing and for monitoring Pb levels, it has not been possible to determine which rat line provides the best model for low level Pb toxicity studies. This study was designed to address this issue.

The effects of low-level Pb on steroidogenic acute regulatory protein (StAR) in the prepubertal rat ovary.

Estradiol (E2) is suppressed in prepubertal females exposed maternally to lead (Pb); thus, we assessed effects of Pb on ovarian steroidogenic acute regulatory protein (StAR) as a potential mechanism for this action. Adult Fisher 344 females were dosed with 12 mg of lead acetate per ml of Pb acetate (PbAc) or sodium acetate (NaAc; control), beginning 30 days prior to breeding and continuing until their pups were weaned. For the first part of this study, animals from both groups were killed when 31 days old, at 0800 h, for assessment of basal ovarian StAR gene expression.

Morphine conditioned place preference is attenuated by perinatal lead exposure.

The purpose of this investigation was to determine if perinatal lead exposure alters the conditioned reinforcing properties of morphine when offspring were tested as adults. Dams were gavaged daily with 0- (sodium acetate) or 16-mg lead (as lead acetate) for 30 days prior to breeding with nonexposed males. Administration continued through gestation and lactation and was discontinued at weaning (postnatal day [PND] 21).

Lead-induced cell signaling cascades in GT1-7 cells.

The effects of lead on the signal transduction pathways that may be involved in the release of gonadotropin-releasing hormone (GnRH) from neurons in the hypothalamus have not been well defined. Using the GT1-7 cell line, an in vitro model for GnRH-secreting neurons, we examined signal transduction pathways directly affected by lead. We found that lead-induced phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1 and ERK2), as well as p90RSK and cAMP response element-binding protein (CREB), but did not induce IkappaB degradation.

Perinatal lead exposure and relapse to drug-seeking behavior in the rat: a cocaine reinstatement study.

Rationale: Intravenous self-administration of cocaine at low doses is increased by chronic low-level exposure to lead during gestation and lactation (perinatal lead exposure). Insofar as drug potency is increased by early lead exposure, it must be considered that cocaine-seeking and relapse after periods of withdrawal similarly may be enhanced by perinatal lead exposure.

Objectives: Employing an animal model, the present study examined the effects of lead exposure during gestation and lactation on cocaine-induced reinstatement of drug-seeking, when animals were tested as adults.

Effects of lead (Pb) exposure during gestation and lactation on female pubertal development in the rat.

Lead (Pb) can delay sexual maturation; however, the mechanism and critical time of insult are not clearly defined. Therefore, we assessed maternal Pb levels during low-level gestational and/or lactational exposure, as well as blood and tissue Pb in developing fetuses in relation to the subsequent detrimental effects of Pb on puberty-related hormones and the onset of female puberty. Adult Fisher 344 female rats were gavaged daily with either a 1-ml solution of PbAc containing 12 mg/ml Pb or an equal volume of sodium acetate (NaCl), for the controls, from 30 days prior to breeding until their pups were weaned at 21 days.