Project description:We tested the effects of chronic paternal nicotine exposure in C57BL6/J mice on hippocampal DNA methylation in F1 offspring. Overall design: Examination of differential DNA methylation in the hippocampus of offspring from males treated chronically with nicotine or males treated chronically with saline.
Project description:We tested the effects of chronic paternal nicotine exposure in C57BL6/J mice on hippocampal RNA expression in F1 offspring. Overall design: Examination of differential gene expression in the hippocampus of offspring from males treated chronically with nicotine or males treated chronically with saline.
Project description:Paternal environmental conditions can influence phenotypes in future generations, but it is unclear whether offspring phenotypes represent specific responses to particular aspects of the paternal exposure history, or a generic response to paternal 'quality of life'. Here, we establish a paternal effect model based on nicotine exposure in mice, enabling pharmacological interrogation of the specificity of the offspring response. Paternal exposure to nicotine prior to reproduction induced a broad protective response to multiple xenobiotics in male offspring. This effect manifested as increased survival following injection of toxic levels of either nicotine or cocaine, accompanied by hepatic upregulation of xenobiotic processing genes, and enhanced drug clearance. Surprisingly, this protective effect could also be induced by a nicotinic receptor antagonist, suggesting that xenobiotic exposure, rather than nicotinic receptor signaling, is responsible for programming offspring drug resistance. Thus, paternal drug exposure induces a protective phenotype in offspring by enhancing metabolic tolerance to xenobiotics.
Project description:Although it is increasingly accepted that some paternal environmental conditions can influence phenotypes in future generations, it remains unclear whether phenotypes induced in offspring represent specific responses to particular aspects of the paternal exposure history, or whether they represent a more generic response to paternal “quality of life”. To establish a paternal effect model based on a specific ligand-receptor interaction and thereby enable pharmacological interrogation of the offspring phenotype, we explored the effects of paternal nicotine administration on offspring phenotype in mouse. We show that paternal exposure to chronic nicotine induced a broad protective response to xenobiotic exposure in the next generation. This effect manifested as increased survival following an injection of toxic levels of nicotine, was specific to male offspring, and was only observed after these offspring were first acclimated to low levels of nicotine for a week. Importantly, offspring xenobiotic resistance was documented not only for toxic nicotine challenge, but also for toxic cocaine challenge, indicating that paternal nicotine exposure reprograms offspring to become broadly resistant to environmental toxins. Mechanistically, the reprogrammed state was characterized by enhanced clearance of nicotine in drug-acclimated animals, and we found that isolated hepatocytes displayed upregulation of enzymes that metabolize xenobiotics. Taken together, our data show that paternal nicotine exposure induces a protective phenotype in offspring by enhancing metabolic tolerance to xenobiotics in the environment. Overall design: Hepatocytes were isolated from eight week-old male F1 animals from control (TA) and nicotine-exposed fathers, 4 biological replicates each.
Project description:Despite the ubiquitous use of Pavlovian fear conditioning as a model for fear learning, the highly predictable conditions used in the laboratory do not resemble real-world conditions, in which dangerous situations can lead to unpleasant outcomes in unpredictable ways. In the current experiments, we varied the timing of aversive events after predictive cues in rodents and discovered that temporal ambiguity of aversive events greatly enhances fear. During fear conditioning with unpredictably timed aversive events, pharmacological inactivation of the dorsal hippocampus or optogenetic silencing of cornu ammonis 1 cells during aversive negative prediction errors prevented this enhancement of fear without affecting fear learning for predictable events. Dorsal hippocampal inactivation also prevented ambiguity-related enhancement of fear during auditory fear conditioning under a partial-reinforcement schedule. These results reveal that information about the timing and occurrence of aversive events is rapidly acquired and that unexpectedly timed or omitted aversive events generate hippocampal signals to enhance fear learning.
Project description:Thyroid hormone (TH) receptors are highly distributed in the hippocampus, which plays a vital role in memory processes. However, how THs are involved in the different stages of memory process is little known. Herein, we used hippocampus dependent contextual fear conditioning to address the effects of hippocampal THs on the different stages of fear memory. First, we found that a single systemic levothyroxine (LT4) administration increased the level of free triiodothyronine (FT3) and free tetraiodothyroxine (FT4) not only in serum but also in hippocampus. In addition, a single systemic LT4 administration immediately after fear conditioning significantly impaired fear memory. These results indicated the important role of hippocampal THs in fear memory process. To further confirm the effects of hippocampal THs on the different stages of fear memory, LT4 (0.4 μg/μl, 1 μl/side) was injected bilaterally into hippocampus. Rats given LT4 into hippocampus before training or tests had no effect on the acquisition or retrieval of fear memory, however rats given LT4 into hippocampus either immediately or 2 h after training showed being significantly impaired fear memory, which demonstrated LT4 administration into hippocampus impairs the consolidation but has no effect on the acquisition and retrieval of fear memory. Furthermore, hippocampal injection of LT4 did not affect rats' locomotor activity, thigmotaxis and THs level in prefrontal cortex (PFC) and serum. These findings may have important implications for understanding mechanisms underlying contribution of THs to memory disorders.
Project description:Advanced paternal age (APA) at conception has been linked with autism and schizophrenia in offspring, neurodevelopmental disorders that affect social functioning. The current study explored the effects of paternal age on social development in the general population.We used multilevel growth modeling to investigate APA effects on socioemotional development from early childhood until adolescence, as measured by the Strengths and Difficulties Questionnaire (SDQ) in the Twins Early Development Study (TEDS) sample. We also investigated genetic and environmental underpinnings of the paternal age effects on development, using the Additive genetics, Common environment, unique Environment (ACE) and gene-environment (GxE) models.In the general population, both very young and advanced paternal ages were associated with altered trajectory of social development (intercept: p = .01; slope: p = .03). No other behavioral domain was affected by either young or advanced age at fatherhood, suggesting specificity of paternal age effects. Increased importance of genetic factors in social development was recorded in the offspring of older but not very young fathers, suggesting distinct underpinnings of the paternal age effects at these two extremes.Our findings highlight that the APA-related deficits that lead to autism and schizophrenia are likely continuously distributed in the population.