The Anti-(+)-Methamphetamine Monoclonal Antibody mAb7F9 Attenuates Acute (+)-Methamphetamine Effects on Intracranial Self-Stimulation in Rats

Passive immunization with monoclonal antibodies (mAbs) against (+)-methamphetamine (METH) is being evaluated for the treatment of METH addiction. A human/mouse chimeric form of the murine anti-METH mAb7F9 has entered clinical trials. This study examined the effects of murine mAb7F9 on certain addiction-related behavioral effects of METH in rats as measured using intracranial self-stimulation (ICSS). Initial studies indicated that acute METH (0.1-0.56 mg/kg, s.c.) lowered the minimal (threshold) stimulation intensity that maintained ICSS. METH (0.3 mg/kg, s.c.) also blocked elevations in ICSS thresholds (anhedonia-like behavior) during spontaneous withdrawal from a chronic METH infusion (10 mg/kg/day x 7 days). In studies examining effects of i.v. pretreatment with mAb7F9 (at 30, 100, or 200 mg/kg), 200 mg/kg blocked the ability of an initial injection of METH (0.3 mg/kg, s.c.) to reduce baseline ICSS thresholds, but was less capable of attenuating the effect of subsequent daily injections of METH. MAb7F9 (200 mg/kg) also produced a small but significant reduction in the ability of METH (0.3 mg/kg, s.c.) to reverse METH withdrawal-induced elevations in ICSS thresholds. These studies demonstrate that mAb7F9 can partially attenuate some addiction-related effects of acute METH in an ICSS model, and provide some support for the therapeutic potential of mAb7F9 for the treatment of METH addiction.     

Nicotine infusion alters leptin and uncoupling protein 1 mRNA expression in adipose tissues of rats

We attempted to clarify whether leptin and uncoupling protein 1 (UCP1) are involved in the action of nicotine on the energy balance. Male Wistar rats were infused subcutaneously with nicotine (12 mg x kg(-1) x day(-1)) for 4 or 14 days. At the end of the 4-day period, the plasma concentrations of leptin of the nicotine-treated and pair-fed rats were lower than those of the freely fed rats, although the levels of leptin mRNA expression in various white adipose tissues did not differ among the three groups. At the end of the 14-day nicotine infusion period, plasma concentrations of leptin were higher, and leptin mRNA expression in the omentum and epididymal and retroperitoneal adipose tissues was stronger in the nicotine-treated rats than in the pair-fed and freely fed rats. UCP1 mRNA expression in the brown adipose tissue of nicotine-treated was stronger than that of the pair-fed rats. These results suggest that continuous nicotine infusion differentially affects the synthesis and secretion of leptin according to the duration of infusion and stimulates UCP1 mRNA expression, probably in a manner independent of leptin.     

Nicotine dependence in rats

Health hazards associated with nicotine and tobacco use are well known. A contributing factor, the dependence producing potential of this drug, has become widely accepted. However, there are only a few human and animal studies that provide objective measures of the behavioral consequences of nicotine abstinence. The purpose of the present experiment was to use sensitive measures to examine behavioral disruptions that resulted when nicotine administration was terminated. Six rats were administered 96 daily intravenous infusions of nicotine (0.125 mg/kg/infusion) for at least 10 days. They were trained to respond on a tongue-operated solenoid-driven drinking device that delivered 0.005 ml of a glucose and saccharin solution (G + S) per lick. When nicotine access was terminated for six days, there was a marked suppression in behavior reinforced by the sweetened solution, and this disruption was immediately reversed when nicotine was reinstated. In contrast, nicotine removal also resulted in a decrease in food intake on the first day, but on subsequent days food intake was significantly higher than when nicotine was administered. When cotinine (0.25 mg/kg/infusion), a metabolite of nicotine was substituted for nicotine for six days, similar disruptions resulted in responding maintained by G + S, but food intake was not significantly decreased on the first day of nicotine abstinence. These findings illustrate the utility of sensitive behavioral tests to reveal effects of nicotine abstinence.     

Efficacy of providing nicotine in a liquid diet to rats.

To determine if rats would consume nicotine at psychoactive levels, a nutritionally balanced diet with 0, 20, 60, or 200 mg of nicotine tartrate per kg of diet was provided. Diet consumption and body weight differences were recorded for 14 days after which, following 16 hr of withdrawal, animals were given access to a two-bottle choice of the previously presented diet and a nicotine-free diet. Spontaneous horizontal motor activity was recorded 8, 16, and 24 hr after withdrawal. By Day 14, all animals showed a significant increase in diet consumption and significant weight gain compared to Day 1. Animals consumed an average of 2.1, 6.8, or 19.5 mg/kg/day of nicotine on the low, medium, and high-nicotine diets, respectively. However, animals receiving the high-nicotine diet consumed less diet and gained less weight than the control, low, and medium nicotine groups. During only the first 4 hr of the two-bottle choice (16-20 hr postwithdrawal), the high-nicotine group consumed significantly higher amounts of nicotine base than the other groups, but also consumed more of the control diet during the first 2 hr. In a replicate experiment, animals receiving the medium-nicotine diet showed an increased consumption of the nicotine diet and increased preference for nicotine following a 14-day exposure compared to the control-fed animals and compared to a baseline preference test. Also, this group showed differences in locomotor activity consistent with other studies using an injection regimen or subcutaneuos pumps to induce dependence. Finally, animals in all three groups exhibited high plasma nicotine and cotinine (a major nicotine metabolite) levels. Because animals in all groups tolerated the diet well, gained weight, selected the nicotine diet in a choice test, and showed withdrawal symptoms, we conclude that the liquid diet proved to be a satisfactory method of inducing nicotine dependence in rats.     

Nicotine ingestion reduces elevated blood pressures in rats and squirrel monkeys

Nicotine tartrate (0.002 -5.0 mg/kg/day) was added to the home cage drinking water of albino rat and squirrel monkey subjects for periods from 1 – 10 weeks. Rats received the drug for approximately 10 weeks and were then implanted with a chronic aortic cannula, allowed to recuperate, and blood pressure measured before and following exposure to a mild tail pinch procedure. All subjects receiving nicotine showed reduced blood pressure elevations to noxious stimulation compared to water control subjects, and these reductions were greater at higher drug doses. Squirrel monkeys exhibiting widely differing resting blood pressures were administered chronic dosages of nicotine. Subjects having high blood pressures showed dose-dependent blood pressure decreases, whereas subjects possessing low resting pressures demonstrated little or no pressure change during drug intake. A follow up study with high blood pressure subjects measured effects of progressive increases in drug followed by a return to drug-free water drinking solutions. Here again a dose-dependent decrease in both systolic and diastolic blood pressures were observed. Upon termination of drug intake, pressures rapidly increased to pre-drug levels. The results are concordant with previous studies demonstrating that oral nicotine ingestion causes reductions in aggresive behavior, and suggest that nicotine is selectively influential in altering the biological state of anger, decreasing both its behavioral and somatic components.     

Nicotine Effects on Dopamine Clearance in Rat Nucleus Accumbens

Abstract: In vivo voltammetry was used to measure the clearance of exogenously applied dopamine (DA) in the nucleus accumbens following acute systemic nicotine administration in urethane-anesthetized rats. The IVEC-5 system was used for continuous in vivo electrochemical measurements. A finite amount of DA was pressure-ejected (25–100 nl, 200 µ M barrel concentration) at 5-min intervals from micropipettes (tip diameter, 10–15 µm) positioned 250 ± 50 µm from the recording electrode. The peak DA concentration after each DA ejection was significantly decreased in rats following nicotine, but not in rats given saline. In addition, when mecamylamine was administered 20 min before nicotine it clearly antagonized nicotine effects. These results suggest that nicotine may actually facilitate DA transporter systems within the nucleus accumbens.     

Nicotine enhances delayed matching-to-sample performance by primates

The non-human primate provides an excellent model for studies of learning and memory, and one particular test, the delayed matching-to-sample task, is performed in a similar manner by both humans and non-human primates. Five young adult macaques were employed in this study, displaying variable capacities for retention in the task. Baseline performance was very consistent and three levels of performance difficulties (95-100%, 80-85% and 65-75% correct choices) were employed by including several delay intervals (0-60 sec) in each session. A reproducible enhancement in performance by nicotine in macaques performing a delayed matching-to-sample task was demonstrated. Nicotine enhanced performance with an average increase of 10% at the longest retention delay interval. This beneficial effect of nicotine was abolished in animals pretreated with a low dose (0.5 mg/kg) of mecamylamine to block central nicotinic receptors. Selective blockade of peripheral nicotinic receptors with hexamethonium was without effect on the nicotine response. A high dose (2 mg/kg) of mecamylamine itself induced a marked inhibition of performance, while an equivalent dose of hexamethonium was without effect. These experiments point to the possibility that central nicotinic receptors may be exploited pharmacologically to enhance memory performance. In this respect it is interesting that nicotine was most effective at enhancing performance when recall was more difficult, that is, on the longer retention interval delays. This could signify that nicotine might be particularly effective in the most impaired individuals. Lastly, it is encouraging that the mecamylamine induced decrease in cognitive performance might provide a new model of memory impairment from which to study the pathogenesis and develop new pharmacological strategies for the dementias.     

Nicotine increases sucrose self-administration and seeking in rats

Associations between nicotine in cigarettes and food consumption may alter the incentive value of food such that food cue-reactivity is exaggerated during abstinence from smoking. This effect may contribute to the weight gain associated with cessation of smoking. We examined the effects of nicotine (0.4 mg/kg base subcutaneous) paired (NPD) or unpaired (NUP) with 10% sucrose self-administration (SA; 0.2 ml/delivery, 1 h/day for 10 days) on SA response rate and intake as well as sucrose cue-reactivity following either 1 or 30 days of forced abstinence. Rats were administered the training dose of nicotine prior to a second, consecutive cue-reactivity session. NPD rats responded at over three times the rate for sucrose and earned nearly twice the number of sucrose deliveries as NUP rats or saline controls. Sucrose cue-reactivity was greater after 30 days versus 1 day of forced abstinence for all groups. History of nicotine exposure had no effect on sucrose cue-reactivity. However, the subsequent injection of nicotine increased sucrose cue-reactivity only in the NPD groups. There were no abstinent-dependent effects of nicotine challenge on sucrose cue-reactivity. A study conducted in parallel with water as the reinforcer revealed a less dramatic effect of nicotine on intake. There was no history or abstinence-dependent effects of nicotine on water cue-reactivity. Nicotine increases the reinforcing effects of sucrose and sucrose-paired cues when nicotine is present. An implication of these findings is that relapse to nicotine (cigarettes) could substantially elevate food cue-reactivity.     

Estradiol lowers intracranial self-stimulation thresholds and enhances cocaine facilitation of intracranial self-stimulation in rats

Women initiate cocaine use at a younger age and have more complications (e.g., higher rates of major or minor depression) related to cocaine use than men. It has been proposed that estrogens play an important role in these sex differences. The addictive potential of psychoactive drugs can be measured in rats via a rewarding intracranial self-stimulation (ICSS) procedure. The rate-independent method of ICSS allows researchers to assess the “pure” rewarding effect of cocaine without influence of nonspecific motor reactions. The present study aimed to estimate effects of estradiol and a combination of estradiol and cocaine on ICSS in ovariectomized female rats. 17-β-estradiol (5 μg/animal/day, 2 days) produced a long-lasting gradual lowering of the thresholds for ICSS. The ability of estradiol to decrease thresholds for ICSS has never been shown previously. Combination of 17-β-estradiol and cocaine (5.0 mg/kg, 5 days) produced a greater effect on ICSS thresholds than the effect of either compound alone. No tolerance or sensitization to cocaine developed during the study. Present findings suggest estradiol increases sensitivity of the brain reward system in rats, which may have an important implication in understanding sex differences in cocaine effects.     

Chronic nicotine exposure alters blood-brain barrier permeability and diminishes brain uptake of methyllycaconitine

Methyllycaconitine (MLA) is reported to be a selective antagonist for the nicotinic acetylcholine receptor alpha7 subtype and has been found in animal behavioral studies to reduce nicotine self-administration and attenuate nicotine withdrawal symptoms. While MLA crosses the blood-brain barrier (BBB), no studies have assessed brain uptake in animals subjected to chronic nicotine exposure. Given that chronic nicotine administration has been reported to alter BBB parameters that may affect the kinetic BBB passage of MLA, we evaluated MLA brain uptake in naive and S-(-)nicotine-exposed rats (4.5 mg/kg/day for 28 days; osmotic minipumps) using in situ rat brain perfusions. Our results demonstrate that in situ(3)H-MLA brain uptake rates in naive animals approximate to intravenous kinetic data (K(in), 3.24 +/- 0.71 x 10(-4) mL/s/g). However, 28-day nicotine exposure diminished (3)H-MLA brain uptake by approximately 60% (K(in), 1.29 +/- 0.4 x 10(-4) mL/s/g). This reduction was not related to nicotine-induced (3)H-MLA brain efflux or BBB transport alterations. Similar experiments also demonstrated that the passive permeation of (14)C-thiourea was diminished approximately 24% after chronic nicotine exposure. Therefore, it appears that chronic nicotine exposure diminishes the blood-brain passive diffusion of compounds with very low extraction rates (i.e. permeability-limited compounds). These findings imply that the pharmacokinetics of neuropharmaceutical agents that are permeability limited may need to be re-evaluated in individuals exposed to nicotine.     

The influence of maternal nicotine exposure on neonatal lung carbohydrate metabolism.

The influence of maternal nicotine exposure (1 mg/kg body mass/day) during pregnancy and lactation on energy metabolism of lung tissue of neonatal rats were investigated. The glucose turnover of the lung tissue of the neonatal rats exposed to nicotine via the placenta and mother's milk was 86.4% higher than that of the controls. Glycolysis was however suppressed by 22.7% (P < 0.01). The adenine nucleotide pool (ATP+ADP+AMP) was 32.8% higher for the lungs of the 3 week old neonates exposed to nicotine than that of the control rat lung. After 4 weeks of nicotine withdrawal glycolysis of those animals exposed to nicotine were still inhibited to the same extent than during exposure. The adenine nucleotide pool was 69.95% higher than that of the controls. It is proposed that the inhibition of glycolysis was due to the high ATP/ADP ratio of the lungs of the nicotine exposed rats.     

Effects of beta-carboline-ethyl ester on plasma corticosterone--a parallel with antagonist-precipitated diazepam withdrawal

Diazepam has been shown to produce physical dependence based on observations of behavioral stimulation or, in our laboratory, by increases in plasma corticosterone (CS) during antagonist-precipitated withdrawal. The behavioral excitation appears similar to that observed following the administration of beta-carboline esters--agents reported to interact with benzodiazepine receptors and termed "inverse agonists." The focus of the present study is to correlate the occurrence of changes in CS with behavioral excitation previously observed by others. Further, these studies are designed to show a parallel between the manifestations of benzodiazepine withdrawal and the pharmacologic effects of beta-carboline ethyl ester. Experiments were done in conscious unrestrained male Sprague-Dawley rats, with chronic i.v. catheters, using sound-attenuated one-way vision boxes. These studies compared the hormonal and behavioral changes induced by beta-carboline ethyl ester (beta CCE) with CGS-8216-precipitated withdrawal in rats treated with diazepam for 8 days. Rats treated chronically with diazepam (5 mg/kg/day), showed a significant increase in plasma (CS) following CGS-8216. Behavioral abstinence scores were also significantly elevated. beta CCE (0.5-5.0 mg/kg) showed a significant dose-related increase in plasma CS. Behavioral scores were also increased at doses of 0.5 and 2.0 mg/kg. beta CCE-induced plasma CS increases were antagonized by CGS-8216 at doses of 1.0 and 2.0 mg/kg but not by 0.5 mg/kg. In animals chronically treated with diazepam, beta CCE evoked a more prolonged plasma CS elevation than in vehicle-treated animals suggesting a dual agonist/antagonist effect. These data suggest a parallel between CS elevations and behavioral effects during withdrawal as well as similarities between the action of beta CCE and the manifestations of this withdrawal.     

Nicotine Exposure Does not Alter Plasma to Brain Choline Transfer

Acute and chronic nicotine exposure in rats is associated with an increase in brain acetylcholine (ACh) transmission. The acquisition of choline for neuronal ACh synthesis occurs primarily via two pathways; first, free choline is transported from the blood across the blood-brain barrier (BBB) and/or second, from synaptic choline generated by either hydrolysis of non-bound ACh or membrane phosphatidylcholine catabolism. To determine if nicotine-induced cholinergic demand is associated with increased choline transport rates into brain, we measured BBB choline transport in naïve and S-(−) nicotine exposed rats (acute and chronic, 4.5 mg/kg/d for 1, 14, 21 and 28 d; osmotic minipumps) using the in situ rat brain perfusion technique. No significant changes in choline uptake after acute or chronic nicotine exposure were observed in whole brain or cortex. Of considerable interest was a significant decrease in regional brain choline uptake measured in the hippocampus after chronic nicotine exposure (28 d). Our data suggest that the increased ACh transmission observed after nicotine exposure does not correlate with increased blood-to-brain transfer of choline. Considering these data and previous literature reports, we propose that the additional free choline required under conditions of nicotine exposure (for ACh synthesis) is primarily recruited from membrane phospholipid metabolism.     

Plasma concentration of prolactin during four-day osmotic pump infusion of thyrotropin-releasing hormone and vasoactive intestinal polypeptide in rats

Pituitary prolactin (PRL) responses to 4-day continuous infusion of thyrotropin-releasing hormone (TRH) and vasoactive intestinal polypeptide (VIP) were investigated in unanesthetized male rats using Alzet osmotic minipumps. The TRH dose infused was 3.6 micrograms/day and the VIP dose was 32.8 micrograms/day. Infusion of TRH with osmotic pumps elevated the plasma PRL level compared to controls over the 4-day infusion period. However, mean levels of PRL tended to decrease during the 4-day infusion. On the other hand, continuous VIP infusion elicited a significant continuous PRL release over the 4-day infusion period. Thus, it may be said that the PRL responses to infused TRH and VIP were maintained during the 4-day infusion.     

Nicotine induced seizures blocked by mecamylamine and its stereoisomers.

Recent genetic research has shown that certain forms of epilepsy may arise from mutations in the genes encoding for the alpha7 and alpha4 neuronal nicotinic acetylcholine receptor (nAChR) ion channels. These receptors are also involved with the induction of nicotine-induced seizures. (+/-)-Mecamylamine (Inversine), a classic nAChR antagonist, potently inhibits nicotine-induced seizures. The purpose of the present study was to assess the inhibitory effects of (+/-)-mecamylamine and its stereoisomers on nicotine-induced seizures in male Sprague-Dawley rats. Rats received saline, (+/-)-mecamylamine, R-(-)-mecamylamine, or S-(+)-mecamylamine (s.c.) at doses of 0.1, 0.3, or 1.0 mg/kg 15 minutes prior to nicotine injection, 3.6 mg/kg (s.c.), an optimal dose for seizure induction. Rats were observed for 30 minutes with seizure latency, duration, and severity as primary measures and locomotor activity recorded as a secondary measure at 5-minute intervals. The results indicate that mecamylamine and each of its stereoisomers block nicotine-induced seizures in a dose-related manner and suggest that the S-(+/-)- mecamylamine isomer has inhibitory properties more similar to the racemic than to the R-(-)-mecamylamine isomer. The results of this study may be clinically important for the future design of novel anti-seizure medications.     

Effects of Chronic and Subchronic Nicotine on Tyrosine Hydroxylase Activity in Noradrenergic and Dopaminergic Neurones in the Rat Brain

Chronic nicotine (0.8 mg/kg by daily subcutaneous injection) over a 7 to 28-day period was found to increase the activity of tyrosine hydroxylase in predominantly noradrenergically innervated regions but not in dopaminergic projection areas. Increases in tyrosine hydroxylase activity were observed in dopaminergic cell body regions only after nicotine treatment for 3 to 5 days. The increase in tyrosine hydroxylase activity in noradrenergic neurones was evident first in the cell bodies in the locus coeruleus from 3 to 7 days, reaching 223% of control activities, and was followed by increases of up to 205% in the terminals up to 3 weeks later. It was then established that nicotine for 7 days was sufficient to increase the activity of the enzyme to the same extent in the terminals at 21 days even without further nicotine administration. This is consistent with axonal transport preceded by induction of the enzyme in noradrenergic cell bodies, whereas "delayed activation" might account for the transient effect seen in dopaminergic cell body regions. The response in the locus coeruleus to nicotine for 7 days was completely blocked by daily preinjection with mecamylamine but not with hexamethonium, which is consistent with the effect of nicotine on tyrosine hydroxylase being mediated by central nicotinic receptors.     

Endocannabinoid regulation of acute and protracted nicotine withdrawal: effect of FAAH inhibition

Evidence shows that the endocannabinoid system modulates the addictive properties of nicotine. In the present study, we hypothesized that spontaneous withdrawal resulting from removal of chronically implanted transdermal nicotine patches is regulated by the endocannabinoid system. A 7-day nicotine dependence procedure (5.2 mg/rat/day) elicited occurrence of reliable nicotine abstinence symptoms in Wistar rats. Somatic and affective withdrawal signs were observed at 16 and 34 hours following removal of nicotine patches, respectively. Further behavioral manifestations including decrease in locomotor activity and increased weight gain also occurred during withdrawal. Expression of spontaneous nicotine withdrawal was accompanied by fluctuation in levels of the endocannabinoid anandamide (AEA) in several brain structures including the amygdala, the hippocampus, the hypothalamus and the prefrontal cortex. Conversely, levels of 2-arachidonoyl-sn-glycerol were not significantly altered. Pharmacological inhibition of fatty acid amide hydrolase (FAAH), the enzyme responsible for the intracellular degradation of AEA, by URB597 (0.1 and 0.3 mg/kg, i.p.), reduced withdrawal-induced anxiety as assessed by the elevated plus maze test and the shock-probe defensive burying paradigm, but did not prevent the occurrence of somatic signs. Together, the results indicate that pharmacological strategies aimed at enhancing endocannabinoid signaling may offer therapeutic advantages to treat the negative affective state produced by nicotine withdrawal, which is critical for the maintenance of tobacco use.     

Local Perfusion of Nicotine Differentially Modulates Somatodendritic Dopamine Release in the Rat Ventral Tegmental Area After Nicotine Preexposure

We examined the effects of nicotine perfusion into the ventral tegmental area (VTA) on extracellular dopamine (DA) levels in rats using in vivo microdialysis. Local perfusion with nicotine for 80 min (10–100 M) modestly increased (105–131% of basal) the extracellular DA levels in the VTA of rats that had been pretreated with saline for 5 days. In animals that had been pretreated with nicotine for 5 days (0.3 mg/kg, s.c.), perfusion with nicotine for 80 min (10–100 M) dose-dependently increased the extracellular DA levels in the VTA of rats and did so to a greater extent than in saline-pretreated animals (125–171% of basal). Co-perfusion through the dialysis probe with 100 M mecamylamine, a nonselective nicotinic acetylcholine receptor (nAChR) antagonist, or 100 M dihydro--erythroidine, a high affinity and competitive nAChR antagonist, attenuated the enhancement of extracellular DA levels produced by 100 M nicotine alone. These results suggest that local nicotine challenge potentiated the somatodendritic DA release after nicotine preexposure by stimulation of high-affinity nAChRs in the VTA.     

Influence of maternal nicotine exposure on neonatal rat bone: protective effect of pentoxifylline

Limited research in young adults and immature animals suggests a detrimental effect of tobacco on bone during growth. The aim of this study was to determine the adverse effects of maternal nicotine exposure during pregnancy and lactation on neonatal rat bone development, and to determine a protective effect of pentoxifylline (PTX). Gravid rats were assigned into four groups, one control (group I) and three experimental (groups II, III, and IV). In group II, pregnant rats received 3 mg/kg/day nicotine alone, subcutaneously, until 21 days postnatal. In group III, pregnant rats received nicotine (3 mg/kg/day) and PTX (60 mg/kg/day). In group IV, pregnant rats received PTX alone (60 mg/kg/day). Whole body mineral density (BMD), content (BMC), area (BA), and histopathologic and morphologic findings of the femur were determined at 21 days of age. The study revealed that nicotine exposure (group II) decreased birth weight, pregnancy weight gain, and length of femur compared with other groups (P < 0.01). Birth weight was higher in groups III (PTX + nicotine) and IV (PTX) than in group II (nicotine). Body weight at 21 days of age was higher (P = 0.009) in the PTX alone group (group IV) compared with the other groups. BMD was higher (P < 0.001) in the PTX-treated groups (group III and IV) compared with other groups. In addition, there were more apoptotic chondrocytes in the hypertrophic zone of rats exposed to nicotine alone (group II) compared with the other groups (P < 0.001). In conclusion, maternal nicotine exposure resulted in decreased birth weight, pregnancy weight gain, and bone lengthening, and increased apoptosis. Pentoxifylline supplementation was found to prevent the adverse effects of maternal nicotine exposure on BMD and birth weight.