Differential Effects of Passive Immunization with Nicotine-Specific Antibodies on the Acute and Chronic Distribution of Nicotine to Brain in Rats
Vaccination against nicotine blocks or attenuates nicotine-related behaviors relevant to addiction in rats. Passive immunization with nicotine-specific antibodies is an alternative to vaccination with the potential advantages of allowing control of antibody dose and affinity. In the current study, the effects of two antibodies on the distribution of nicotine to brain were evaluated during chronic nicotine administration in rats; the monoclonal antibody Nic311 (K(d) = 60 nM) and nicotine-specific antiserum (K(d) = 1.6 nM). Nicotine was administered via repeated i.v. bolus doses over 2 days and antibody was administered during the first day. Neither antibody appreciably reduced the chronic accumulation of nicotine in brain, despite high protein binding of nicotine in serum (98.9%) and a 73% reduction in the unbound serum nicotine concentration with the highest Nic311 dose. However, both antibodies substantially reduced the early distribution of nicotine to brain 5 min after a dose. The higher affinity antibody was no more effective than Nic311. The highest Nic311 dose produced serum antibody levels 10 times higher than those reported with vaccination. The efficacy of Nic311 was dose-related, with the highest dose producing a 76% decrease in the early distribution of nicotine to brain. These findings, along with previous data, suggest that the primary effect of passive immunization is to slow, rather than prevent, the distribution of nicotine to brain. In the setting of chronic nicotine dosing, antibodies with a moderate affinity for nicotine produced substantial effects on the early distribution of nicotine to brain and were as effective as higher affinity antibodies.
Available from: Lawrence K Silbart
- "Previous studies using monoclonal antibodies have mitigated the acute toxicity effects of drugs such as cocaine, heroin, methamphetamine, colchicine, oleander and other related substances [37,38,39,40]. Others have ameliorated the chronic toxicity associated with chemicals such as PCP, NNK and nicotine [17,41,42,43]. The current work builds upon these studies by creating a high affinity recombinant anti-NNK binding site derived from a mouse monoclonal antibody specific for NNK. "
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ABSTRACT: Smokeless tobacco products have been associated with increased risks of oro-pharyngeal cancers, due in part to the presence of tobacco-specific nitrosamines (TSNAs) such as 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). These potent carcinogens are formed during tobacco curing and as a result of direct nitrosation reactions that occur in the oral cavity. In the current work we describe the isolation and characterization of a hybridoma secreting a high-affinity, NNK-specific monoclonal antibody. A structurally-related benzoyl derivative was synthesized to facilitate coupling to NNK-carrier proteins, which were characterized for the presence of the N-nitroso group using the Griess reaction, and used to immunize BALB/c mice. Splenocytes from mice bearing NNK-specific antibodies were used to create hybridomas. Out of four, one was selected for subcloning and characterization. Approximately 99% of the monoclonal antibodies from this clone were competitively displaced from plate-bound NNKB conjugates in the presence of free NNK. The affinity of the monoclonal antibody to the NNKB conjugates was Kd = 2.93 nM as determined by surface plasmon resonance. Free nicotine was a poor competitor for the NNKB binding site. The heavy and light chain antibody F(ab) fragments were cloned, sequenced and inserted in tandem into an expression vector, with an FMDV Furin 2A cleavage site between them. Expression in HEK 293 cells revealed a functional F(ab) with similar binding features to that of the parent hybridoma. This study lays the groundwork for synthesizing transgenic tobacco that expresses carcinogen-sequestration properties, thereby rendering it less harmful to consumers.
Available from: Amanda J Morgan
- "The most common method is to administer continuous nicotine via osmotic mini-pump to maintain steady-state nicotine levels throughout gestation (Franke et al., 2008; Slotkin et al., 2006; Wei et al., 2011). Pregnant dams are also administered nicotine through drinking water (Pauly et al., 2004; Paz et al., 2007; Zhu et al., 1996), and by IV injection (Harrod et al., 2011; Lacy et al., 2011; LeSage et al., 2006; Pentel et al., 2006). These models provide converging evidence that GN exposure alone produces neurochemical and behavioral changes in offspring (Dwyer et al., 2008). "
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ABSTRACT: Prenatal tobacco smoke exposure is associated with alterations in motivated behavior in offspring, such as increased consumption of highly palatable foods and abused drugs. Animal models show that gestational nicotine (GN) exposure mediates changes in responding for sucrose and drug reward.
A novel, intermittent low-dose intravenous (IV) exposure model was used to administer nicotine (0.05 mg/kg/injection) or saline 3×/day to rats on gestational days 8-21. Two experiments investigated the effect of IV GN on (1) the habituation of spontaneous locomotor activity and on (2) sucrose reinforced responding in offspring. For the operant experiments, animals acquired fixed-ratio (FR-3) responding for sucrose, 26% (w/v), and were tested on varying concentrations (0, 3, 10, 30, and 56%; Latin-square) according to a FR-3, and then a progressive-ratio (PR) schedule. Male and female adult offspring were used.
IV GN did not alter birth or growth weight, or the number of pups born. No between-group differences in habituation to spontaneous locomotor activity were observed. FR testing produced an inverted U-shaped response curve, and rats showed peak responding for 10% sucrose reinforcement. Neither gestation nor sex affected responding, suggesting equivalent sensitivity to varying sucrose concentrations. PR testing revealed that GN rats showed greater motivation for sucrose reinforcement relative to controls.
A low-dose, IV GN exposure model resulted in increased motivation to respond for sucrose reinforcement in adult offspring. This suggests that using a low number of cigarettes throughout pregnancy will result in increased motivation for highly palatable foods in adult, and perhaps, adolescent offspring.
Available from: Mark G. LeSage
- "infusion of either saline or nicotine alone (3.2 mg kg −1 day −1 ), some rats in Experiment 3a (see below) had received an i.v. infusion of control immunoglobin or the nicotine-specific monoclonal antibody Nic311 (see Keyler et al. 2005; Pentel et al. 2006), and all rats in Experiment 3b had received prior exposure to restraint stress. However, rats were treatment free and their performance had been maintained under their respective behavioral assay for 4–9 weeks before beginning the present experiments (32±6, 41±6, and 65±19 days [mean ± SEM] for Experiments 2, 3a, and 3b, respectively). "
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ABSTRACT: Animal models of tobacco addiction rely on administration of nicotine alone or nicotine combined with isolated constituents. Models using tobacco extracts derived from tobacco products and containing a range of tobacco constituents might more accurately simulate tobacco exposure in humans.
To compare the effects of nicotine alone and an aqueous smokeless tobacco extract in several addiction-related animal behavioral models.
Nicotine alone and nicotine dose-equivalent concentrations of extract were compared in terms of their acute effects on intracranial self-stimulation (ICSS) thresholds, discriminative stimulus effects, and effects on locomotor activity.
Similar levels of nicotine and minor alkaloids were achieved using either artificial saliva or saline for extraction, supporting the clinical relevance of the saline extracts used in these studies. Extract produced reinforcement-enhancing (ICSS threshold-decreasing) effects similar to those of nicotine alone at low to moderate nicotine doses, but reduced reinforcement-attenuating (ICSS threshold-increasing) effects at a high nicotine dose. In rats trained to discriminate nicotine alone from saline, intermediate extract doses did not substitute for the training dose as well as nicotine alone. Locomotor stimulant effects and nicotine distribution to brain were similar following administration of extract or nicotine alone.
The reinforcement-attenuating and discriminative stimulus effects of nicotine delivered in an extract of a commercial smokeless tobacco product differed from those of nicotine alone. Extracts of tobacco products may be useful for evaluating the abuse liability of those products and understanding the role of non-nicotine constituents in tobacco addiction.
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