No description available.

The cannabinoid system is involved in many functions of mammalian brain, such as learning and memory, pain perception and 'locomotion. The "brain type" cannabinoid receptor CB 1 is one of the key elements of the cannabinoid system. In this Thesis, some aspects of the neurobiology of mouse CB 1 are described. CB 1 mRNA distribution was analysed by single and double in situ hybridization (ISH), revealing the expression of the receptor in specific neuronal subpopulations. This expression pattern suggests many putative functional cross-talks between the cannabinoid system and other signalling molecules in the brain, such as glutamate, GABA, cholecystokinin and nitric oxide (NO). The putative functional interactions of the cannabinoid system with the NO pathway was studied by pharmacological treatment of neuronal NO synthase (nNOS) mutant mice with the CBI agonist A9-tetrahydrocannabinol (A9-THC). The results showed that nNOS is necessary for some central effects of A9-THC. Moreover, ISH analysis revealed. that nNOS-deficient mice contain levels of CBI lower than normal in selected brain regions. A "conditional" targeting approach was developed to gain insights into the specific functions of CB 1 in mouse brain. By gene targeting experiments, two mutant lines were obtained. The "Flox CB 1" mouse line, containing the whole open reading frame of CB I flanked by two loxP sites will be the key tool for the generation of mouse mutants with a spatiotemporal-restricted deletion of CB I. The "CBN" mice, carrying a "null" mutation of CB 1, were used for a study aimed to clarify some aspects of the in vitro neuroprotective activity of cannabinoids and, in particular, the involvement of CB 1. In vitro oxidative stress assays were performed on cell lines and on primary neuronal cultures derived from homozygous CBN/CBN mice and wild type littermates. The results indicate a differential protective activity of cannabinoids on cell lines and primary cultures. However, CBI does not appear to be involved in the in vitro leuroprotective effects of cannabinoids.

No description available.

No description available.

There is a growing interest in assessing the neurotoxic potential and endocrine disrupting properties of perfluoroalkyl compounds (PFCs). Several studies have reported in vitro and in vivo effects related to neuronal development, neural cell differentiation, pre- and post- natal development and behaviour. PFC exposure altered hormone levels (e.g. thyroid hormone, estrogen, and testosterone) and the expression of hormone-responsive genes in mammalian and aquatic species. Hormone-mediated events are critical in central nervous system development and function, especially those controlled by thyroid hormones (THs). The studies presented in this thesis are the first to assess the effects of PFCs on primary cultures of neuronal cells in two avian species; the domestic chicken (Gallus domesticus) and herring gull (Larus argentatus). The following TH-responsive genes were examined using real-time RT-PCR: type II iodothyronine 5’-deiodinase (D2), D3, transthyretin (TTR), neurogranin (RC3), octamer motif binding factor (Oct-1), and myelin basic protein (MBP). Several PFCs were shown to alter mRNA expression levels of genes associated with the TH pathway in avian neuronal cells. It was determined that short-chained PFCs (<8 carbons) altered the expression of TH-responsive genes to a greater extent than long-chained PFCs (≥8 carbons). Although several significant changes in mRNA expression were observed in TH-responsive genes following PFC exposure in chicken embryonic neuronal (CEN) cells (Chapter 2), there were fewer changes in herring gull embryonic neuronal (HGEN) cells (Chapter 3). The mRNA levels of D2, D3, TTR, and RC3 were altered following treatment with several short-chained PFCs in CEN cells. Oct-1 and RC3 expression were induced following treatment with several short-chained PFCs in HGEN cells. These studies are the first to report that PFC exposure alters mRNA expression in primary cultures of avian neuronal cells and provide insight into the possible mechanisms of action of PFCs in the avian brain.

Brominated flame retardants (BFR) such as hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO), bis(2-ethylhexyl)tetrabromophthalate (BEHTBP), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) and decabromodiphenylethane (DBDPE) are contaminants of environmental concern. These BFRs are replacement alternatives for some of the major production BFRs, which have been restricted from the marketplace due to their adverse health effects. Their presence in environmental matrices, including wild birds, suggests they should be tested for possible toxic effects. BFR alternatives have been detected in the eggs of colonial fish-eating birds, suggesting maternal transfer during ovogenesis and the potential for these chemicals to bioaccumulate through the food chain. However, information regarding the toxicity of HCDBCO, BEHTBP, BTBPE and DBDPE exposure in birds is lacking. This thesis consisted of a combined in vitro/in ovo approach to determine: 1) the concentration-dependent effects of these four BFR alternatives in chicken embryonic hepatocytes (CEH), and 2) the dose-dependent effects of HCDBCO and BTBPE in chicken embryos following injection into the air cell of eggs prior to incubation. Changes in the mRNA expression levels of genes previously found to be responsive to other BFRs were assessed in CEH and liver tissue, in addition to examining overt toxicity (i.e. cytotoxicity, pipping success). None of the BFRs tested were cytotoxic up to 60 µM HCDBCO, 60 µM BEHTBP, 1.4 µM BTBPE or 0.2 µM DBDPE in CEH. Injection doses up to 50 µg/g egg HCDBCO and 10 µg/g egg BTBPE had no effect on embryonic pipping success. The accumulation of HCDBCO and BTBPE was variable in liver and did not follow a linear uptake pattern with respect to injection dose, due in part to difficulties with the solubility of these chemicals in the dimethyl sulfoxide (DMSO) vehicle. In, CEH, HCDBCO caused a decrease in CYP1A4/5 mRNA at all concentrations tested, while CYP2H1 and CYP3A37 were induced only at 10 µM. In contrast, only TTR mRNA was down-regulated in hepatic tissue at all injection concentrations of HCDBCO. The highest concentration of BTBPE induced CYP1A4/5 mRNA to 115- and 18-fold in CEH, and 6.5- and 1.8-fold in liver tissue. In vitro and in ovo exposure to BTBPE caused a concentration-dependent decrease in DIO3 mRNA, while CYP3A37 was down-regulated 2-fold at 10 µg/g in liver tissue. In CEH, DBDPE induced CYP1A4/5 mRNA to a maximum of 29- and 59-fold at 0.2 µM, and increases in DIO1 mRNA and decreases in CYP3A37 mRNA were also observed. None of the gene targets were responsive to BEHTBP exposure in CEH. This is the first study to report on the toxicological and molecular effects of HCDBCO, BEHTBP, BTBPE and DBDPE in an avian species. Using this combined in vitro/in ovo approach has permitted the characterization of these four BFR alternatives by defining possible mechanisms of biological action in a model avian species, the chicken.

There is a growing interest in assessing the neurotoxic potential and endocrine disrupting properties of perfluoroalkyl compounds (PFCs). Several studies have reported in vitro and in vivo effects related to neuronal development, neural cell differentiation, pre- and post- natal development and behaviour. PFC exposure altered hormone levels (e.g. thyroid hormone, estrogen, and testosterone) and the expression of hormone-responsive genes in mammalian and aquatic species. Hormone-mediated events are critical in central nervous system development and function, especially those controlled by thyroid hormones (THs). The studies presented in this thesis are the first to assess the effects of PFCs on primary cultures of neuronal cells in two avian species; the domestic chicken (Gallus domesticus) and herring gull (Larus argentatus). The following TH-responsive genes were examined using real-time RT-PCR: type II iodothyronine 5’-deiodinase (D2), D3, transthyretin (TTR), neurogranin (RC3), octamer motif binding factor (Oct-1), and myelin basic protein (MBP). Several PFCs were shown to alter mRNA expression levels of genes associated with the TH pathway in avian neuronal cells. It was determined that short-chained PFCs (<8 carbons) altered the expression of TH-responsive genes to a greater extent than long-chained PFCs (≥8 carbons). Although several significant changes in mRNA expression were observed in TH-responsive genes following PFC exposure in chicken embryonic neuronal (CEN) cells (Chapter 2), there were fewer changes in herring gull embryonic neuronal (HGEN) cells (Chapter 3). The mRNA levels of D2, D3, TTR, and RC3 were altered following treatment with several short-chained PFCs in CEN cells. Oct-1 and RC3 expression were induced following treatment with several short-chained PFCs in HGEN cells. These studies are the first to report that PFC exposure alters mRNA expression in primary cultures of avian neuronal cells and provide insight into the possible mechanisms of action of PFCs in the avian brain.

Brominated flame retardants (BFR) such as hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO), bis(2-ethylhexyl)tetrabromophthalate (BEHTBP), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) and decabromodiphenylethane (DBDPE) are contaminants of environmental concern. These BFRs are replacement alternatives for some of the major production BFRs, which have been restricted from the marketplace due to their adverse health effects. Their presence in environmental matrices, including wild birds, suggests they should be tested for possible toxic effects. BFR alternatives have been detected in the eggs of colonial fish-eating birds, suggesting maternal transfer during ovogenesis and the potential for these chemicals to bioaccumulate through the food chain. However, information regarding the toxicity of HCDBCO, BEHTBP, BTBPE and DBDPE exposure in birds is lacking. This thesis consisted of a combined in vitro/in ovo approach to determine: 1) the concentration-dependent effects of these four BFR alternatives in chicken embryonic hepatocytes (CEH), and 2) the dose-dependent effects of HCDBCO and BTBPE in chicken embryos following injection into the air cell of eggs prior to incubation. Changes in the mRNA expression levels of genes previously found to be responsive to other BFRs were assessed in CEH and liver tissue, in addition to examining overt toxicity (i.e. cytotoxicity, pipping success). None of the BFRs tested were cytotoxic up to 60 µM HCDBCO, 60 µM BEHTBP, 1.4 µM BTBPE or 0.2 µM DBDPE in CEH. Injection doses up to 50 µg/g egg HCDBCO and 10 µg/g egg BTBPE had no effect on embryonic pipping success. The accumulation of HCDBCO and BTBPE was variable in liver and did not follow a linear uptake pattern with respect to injection dose, due in part to difficulties with the solubility of these chemicals in the dimethyl sulfoxide (DMSO) vehicle. In, CEH, HCDBCO caused a decrease in CYP1A4/5 mRNA at all concentrations tested, while CYP2H1 and CYP3A37 were induced only at 10 µM. In contrast, only TTR mRNA was down-regulated in hepatic tissue at all injection concentrations of HCDBCO. The highest concentration of BTBPE induced CYP1A4/5 mRNA to 115- and 18-fold in CEH, and 6.5- and 1.8-fold in liver tissue. In vitro and in ovo exposure to BTBPE caused a concentration-dependent decrease in DIO3 mRNA, while CYP3A37 was down-regulated 2-fold at 10 µg/g in liver tissue. In CEH, DBDPE induced CYP1A4/5 mRNA to a maximum of 29- and 59-fold at 0.2 µM, and increases in DIO1 mRNA and decreases in CYP3A37 mRNA were also observed. None of the gene targets were responsive to BEHTBP exposure in CEH. This is the first study to report on the toxicological and molecular effects of HCDBCO, BEHTBP, BTBPE and DBDPE in an avian species. Using this combined in vitro/in ovo approach has permitted the characterization of these four BFR alternatives by defining possible mechanisms of biological action in a model avian species, the chicken.

There is a growing interest in assessing the neurotoxic potential and endocrine disrupting properties of perfluoroalkyl compounds (PFCs). Several studies have reported in vitro and in vivo effects related to neuronal development, neural cell differentiation, pre- and post- natal development and behaviour. PFC exposure altered hormone levels (e.g. thyroid hormone, estrogen, and testosterone) and the expression of hormone-responsive genes in mammalian and aquatic species. Hormone-mediated events are critical in central nervous system development and function, especially those controlled by thyroid hormones (THs). The studies presented in this thesis are the first to assess the effects of PFCs on primary cultures of neuronal cells in two avian species; the domestic chicken (Gallus domesticus) and herring gull (Larus argentatus). The following TH-responsive genes were examined using real-time RT-PCR: type II iodothyronine 5’-deiodinase (D2), D3, transthyretin (TTR), neurogranin (RC3), octamer motif binding factor (Oct-1), and myelin basic protein (MBP). Several PFCs were shown to alter mRNA expression levels of genes associated with the TH pathway in avian neuronal cells. It was determined that short-chained PFCs (<8 carbons) altered the expression of TH-responsive genes to a greater extent than long-chained PFCs (≥8 carbons). Although several significant changes in mRNA expression were observed in TH-responsive genes following PFC exposure in chicken embryonic neuronal (CEN) cells (Chapter 2), there were fewer changes in herring gull embryonic neuronal (HGEN) cells (Chapter 3). The mRNA levels of D2, D3, TTR, and RC3 were altered following treatment with several short-chained PFCs in CEN cells. Oct-1 and RC3 expression were induced following treatment with several short-chained PFCs in HGEN cells. These studies are the first to report that PFC exposure alters mRNA expression in primary cultures of avian neuronal cells and provide insight into the possible mechanisms of action of PFCs in the avian brain.

Brominated flame retardants (BFR) such as hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO), bis(2-ethylhexyl)tetrabromophthalate (BEHTBP), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) and decabromodiphenylethane (DBDPE) are contaminants of environmental concern. These BFRs are replacement alternatives for some of the major production BFRs, which have been restricted from the marketplace due to their adverse health effects. Their presence in environmental matrices, including wild birds, suggests they should be tested for possible toxic effects. BFR alternatives have been detected in the eggs of colonial fish-eating birds, suggesting maternal transfer during ovogenesis and the potential for these chemicals to bioaccumulate through the food chain. However, information regarding the toxicity of HCDBCO, BEHTBP, BTBPE and DBDPE exposure in birds is lacking. This thesis consisted of a combined in vitro/in ovo approach to determine: 1) the concentration-dependent effects of these four BFR alternatives in chicken embryonic hepatocytes (CEH), and 2) the dose-dependent effects of HCDBCO and BTBPE in chicken embryos following injection into the air cell of eggs prior to incubation. Changes in the mRNA expression levels of genes previously found to be responsive to other BFRs were assessed in CEH and liver tissue, in addition to examining overt toxicity (i.e. cytotoxicity, pipping success). None of the BFRs tested were cytotoxic up to 60 µM HCDBCO, 60 µM BEHTBP, 1.4 µM BTBPE or 0.2 µM DBDPE in CEH. Injection doses up to 50 µg/g egg HCDBCO and 10 µg/g egg BTBPE had no effect on embryonic pipping success. The accumulation of HCDBCO and BTBPE was variable in liver and did not follow a linear uptake pattern with respect to injection dose, due in part to difficulties with the solubility of these chemicals in the dimethyl sulfoxide (DMSO) vehicle. In, CEH, HCDBCO caused a decrease in CYP1A4/5 mRNA at all concentrations tested, while CYP2H1 and CYP3A37 were induced only at 10 µM. In contrast, only TTR mRNA was down-regulated in hepatic tissue at all injection concentrations of HCDBCO. The highest concentration of BTBPE induced CYP1A4/5 mRNA to 115- and 18-fold in CEH, and 6.5- and 1.8-fold in liver tissue. In vitro and in ovo exposure to BTBPE caused a concentration-dependent decrease in DIO3 mRNA, while CYP3A37 was down-regulated 2-fold at 10 µg/g in liver tissue. In CEH, DBDPE induced CYP1A4/5 mRNA to a maximum of 29- and 59-fold at 0.2 µM, and increases in DIO1 mRNA and decreases in CYP3A37 mRNA were also observed. None of the gene targets were responsive to BEHTBP exposure in CEH. This is the first study to report on the toxicological and molecular effects of HCDBCO, BEHTBP, BTBPE and DBDPE in an avian species. Using this combined in vitro/in ovo approach has permitted the characterization of these four BFR alternatives by defining possible mechanisms of biological action in a model avian species, the chicken.