Behavioral effects of smokeless tobacco on the neonate and young sprague Dawley rat
Authors: Paulson Ruth B. , Shanfeld Joseph , Vorhees Charles V. , Cole Jennifer , Sweazy Andrea , Paulson John O. 
Published: June 2005

Three dosages of Smokeless Tobacco (ST) extract were given to pregnant Sprague‐Dawley rats by oral gavage on gestational days (GD) 6–20. The three dosages contained ST extract equivalent to 1.33 mg/kg nicotine (STD‐1), 4.0 mg/kg nicotine (STD‐2), and 6.0 mg/kg nicotine (STD‐3). Dams were intubated three times per day at 8 a.m., 11 a.m., and 2 p.m., providing total daily ST dosages of 4 mg/kg, 12 mg/kg, and 18 mg/kg, respectively. Controls received equivalent volumes of water by gavage. Dams were allowed to deliver, and all biological mothers raised their own pups. On postnatal day 1 (PND 1), litters were culled to 4 ± 1 females and 4 ± 1 males. Weights, physical landmark development, and behavioral performance of pups were monitored during pre‐ and post‐weaning periods. Behavioral tests included surface righting, negative geotaxis, swimming development, open field activity, and active avoidance in shuttle box. Our results show that the two higher doses resulted in reduced maternal weight gain. During the pre‐weaning period, significant pup weight reductions were noted in the STD‐2 pups until PND6, and in the STD‐3 group until PND15. In the STD‐1 group no statistically significant weight reduction was noted on PNDs 1 and 3, but starting with PND6, pup weights surpassed control group weights. This weight difference persisted throughout the post‐weaning period also (P < .05 on PND30 and PND42). The STD‐3 pup weights continued to be consistently and significantly (P < .05) reduced throughout the post‐weaning period (except on PND24); likewise, the STD‐2 pups continued to have lower weights, but at a significant level (P < .05) on PND30 only. The incidence of deaths was increased in a dose‐related manner. No significant differences were noted for pinna detachment and incisor erpton; however ST‐treatment was significant in affecting earlier eye opening and vaginal patency. N significant ST treatment effects were seen on netive geotaxis, but for surface righting a decreasedsuccess rate was noted for the ST‐treated groups. Significant differences were noted in swimming development, with the STD‐2 pups performing best. Open field activity, as expected, increased from the pre‐weaning to post‐weaning periods. During the pre‐weaning period the STD‐3 pups were more active, and during post‐weaning, the STD‐1 pups were more active, but no differences were noted in vertical activity or in the number of stereotypical movements. No treatment‐related differences were noted in the active avoidance shuttle box.

We conclude that at high doses ST reduces pre‐and post‐weaning offspring weight gain and increases fetal mortality. ST at the low dose appears to have the opposite effect, in that these offspring weights actually exceed control weights. ST also alters activity levels and swimming development, while no differences are noted in the rats' performance in active avoidance tests on learning. Therefore, ST exposure during the embryonic and fetal stages of rat development produces developmental toxicity and suggests that its effects may be comparable to results observed by other investigators using smoked tobacco. © 1994 Wiley‐Liss, Inc.