Little is known about the reproductive effects of paternal cannabis exposure. We evaluated associations between cannabis or tetrahydrocannabinol (THC) exposure and altered DNA methylation in sperm from humans and rats, respectively. DNA methylation, measured by reduced representation bisulfite sequencing, differed in the sperm of human users from non-users by at least 10% at 3,979 CpG sites. Pathway analyses indicated Hippo Signaling and Pathways in Cancer as enriched with altered genes (Bonferroni p < 0.02). These same two pathways were also enriched with genes having altered methylation in sperm from THC-exposed versus vehicleexposed rats (p < 0.01). Data validity is supported by significant correlations between THC exposure levels in humans and methylation for 177 genes, and substantial overlap in THC target genes in rat sperm (this study) and genes previously reported as having altered methylation in the brain of rat offspring born to parents both exposed to THC during adolescence. In humans, cannabis use was also associated with significantly lower sperm concentration. Findings point to possible pre-conception paternal reproductive risks associated with cannabis use.

Lorcaserin, a selective 5-hydroxytryptamine 2C (5-HT 2C ) agonist, has been shown to facilitate weight loss in obese populations. It was assessed for its efficacy in reducing nicotine self-administration in young adult female Sprague-Dawley rats. The effect of short-term doses (subcutaneous) on nicotine selfadministration (0.03 mg/kg per infusion) with a fixed ratio 1 schedule was assessed in 3-h sessions. Short-term lorcaserin doses (0.3125-20 mg/kg) were administered in a counterbalanced order. Significant reduction of nicotine self-administration was achieved with all of the short-term doses in this range. Tests of lorcaserin on locomotor activity detected prominent sedative effects at doses greater than 1.25 mg/kg with more modest transient effects seen at 0.625 to 1.25 mg/kg. Longterm effects of lorcaserin on locomotor activity were tested with repeated injections with 0.625 mg/kg lorcaserin 10 times over 2 weeks. This low lorcaserin dose did not cause an overall change in locomotor activity relative to that of saline-injected controls. Long-term lorcaserin (0.625 mg/kg) significantly reduced nicotine self-administration over a 2-week period of repeated injections. Long-term lorcaserin at this same dose had no significant effects on food self-administration over the same 2-week period of repeated injections. These studies support development of the 5-HT 2C agonist lorcaserin to aid tobacco smoking cessation.

Adequate treatment of tobacco addiction remains problematic. Part of the problem with treatment is a poor understanding of the pharmacologic aspects of nicotine contributing to addiction. In addition to activating nicotinic acetylcholine receptors, nicotine also desensitizes them. It is currently not known how much of each of nicotine's actions contribute to its particular behavioral effects. Sazetidine-A (saz-A) is a novel nicotinic receptor-desensitizing agent and partial agonist with high selectivity for ␣4␤2 receptors. The current experiments were conducted to determine whether saz-A would reduce nicotine selfadministration in rats and to characterize its ancillary effects. Adult male Sprague-Dawley rats were allowed to self-administer nicotine. After initial food pellet training followed by 10 sessions of nicotine self-administration training, the rats were administered saz-A (0.1-3 mg/kg s.c.) or the saline vehicle in a repeated-measures counterbalanced design. Saz-A at the 3 mg/kg dose significantly decreased nicotine self-administration relative to performance of the same rats after saline injections. In a second study, long-term administration of this dose of sazetidine-A over the course of 10 sessions significantly reduced nicotine self-administration with no apparent diminution of effect. Saz-A in this dose range had only modest effects on locomotor activity, without any overall decrease in activity over a 1-h-long session. Saz-A significantly reduced food self-administration, but this effect was smaller than its effect on nicotine self-administration. Saz-A, which is a selective ␣4␤2-desensitizing agent and partial agonist, effectively reduces nicotine self-administration. This type of treatment holds promise for a new therapy to aid smoking cessation.

Active maternal smoking has adverse effects on neurobehavioral development of the offspring, with nicotine (Nic) providing much of the underlying causative mechanism. To determine whether the lower exposures caused by second-hand smoke are deleterious, we administered tobacco smoke extract (TSE) to pregnant rats starting preconception and continued through the second postnatal week, corresponding to all 3 trimesters of fetal brain development. Dosing was adjusted to produce maternal plasma Nic concentrations encountered with second-hand smoke, an order of magnitude below those seen in active smokers. We then compared TSE effects to those of an equivalent dose of Nic alone, and to a 10-fold higher Nic dose. Gestational exposure to TSE and Nic significantly disrupted cognitive and behavioral function in behavioral tests given during adolescence and adulthood (postnatal weeks 4-40), producing hyperactivity, working memory deficits, and impairments in emotional processing, even at the low exposure levels corresponding to second-hand smoke. Although TSE effects were highly correlated with those of Nic, the effects of TSE were much larger than could be attributed to just the Nic in the mixture. Indeed, TSE effects more closely resembled those of the 10-fold higher Nic levels, but still exceeded their magnitude. In combination with our earlier findings, this study thus completes the chain of causation to prove that second-hand smoke exposure causes neurodevelopmental deficits, originating in disruption of neurodifferentiation, leading to miswiring of neuronal circuits, and as shown here, culminating in behavioral dysfunction. As low level exposure to Nic alone produced neurobehavioral teratology, 'harm reduction' Nic products do not abolish the potential for neurodevelopmental damage.

The great majority of tobacco addiction begins during adolescence. More heavily addicted smokers begin smoking earlier, but differentiating the neurobehavioral impact of nicotine self-administration during adolescence from self-selection bias (whereby people more prone to heavy addiction also begin earlier) cannot be ethically unconfounded in humans. The goals of this research were to determine the age threshold for the adult-like nicotine self-administration and determine sex differences. Male and female Sprague-Dawley rats were tested for nicotine self-administration starting at 4, 5, 6, 7, and 8 weeks of age in an operant FR1 schedule for IV nicotine (0.03 mg/kg/infusion) in 45-minute sessions for two weeks, with one week of enforced abstinence and one week of resumed access. This study replicated our earlier work that nicotine self-administration was increased in adolescent vs. adult rats and that the effect was more pronounced in adolescent males, but the increased nicotine self-administration was more persistent in adolescent-onset females. The age threshold for adult-like behavior was 6–7 weeks of age. Adolescent-onset nicotine self-administration had persisting effects of eggaurated increases of nicotine self-administration when fixed-ratio requirements for self-administration were lowered. Female rats that had begun nicotine self-administration during adolescence showed exaggerated increases in nicotine self-administration after a switch back to FR1 from FR8, indicating a lessened control over their self-administration. Adolescent-onset nicotine self-administration was not found to potentiate cocaine self-administration. Adolescent-onset nicotine self-administration causes persistent increases in nicotine self-administration in female rats even after they reach adulthood and disrupts control over self-administration behavior.