Estradiol promotes the rewarding effects of nicotine in female rats

Abstract

It is presently unclear whether ovarian hormones, such as estradiol (E2) promote the rewarding effects of nicotine in females. Thus, we compared extended access to nicotine intravenous selfadministration (IVSA) in intact male, intact female, and OVX female rats (Study 1) as well as OVX females that received vehicle or E2 supplementation (Study 2). The E2 supplementation procedure involved a 4-day procedure involving 2 days of vehicle administration and 2 days of E2 administration. Two doses of E2 (25 or 250 ug) were assessed in separate groups of OVX females in order to examine the dose-dependent effects of this hormone on the rewarding effects of nicotine. The rats were given 23-hour access to nicotine IVSA using an escalating dose regimen (0.015, 0.03, and 0.06 mg/kg/0.1 ml). Each dose was self-administered for 4 days with 3 intervening days of nicotine abstinence. The results revealed that intact females displayed higher levels of nicotine intake as compared to males. Also, intact females displayed higher levels of nicotine intake versus OVX females. Lastly, our results revealed that OVX rats that received E2 supplementation displayed a dose-dependent increase in nicotine intake as compared to OVX rats that received vehicle. Together, our results suggest that the rewarding effects of nicotine are enhanced in female rats via the presence of the ovarian hormone, E2.

Variability in nicotine conditioned place preference and stress‐induced reinstatement in mice: Effects of sex, initial chamber preference, and guanfacine

“…We found no significant effect of estrous phase on CPP ( Figure 5), which is consistent with previous studies of intact, freely cycling female rats. 40,84 However, other studies associate higher estradiol levels with greater nicotine reward in rats, 85,86 and higher progesterone levels with protective effects against nicotine reward 87 and relapse 88,89 in human subjects. Our study was insufficiently powered to examine estrous phase within the split subgroups, but it is possible that in the Lo-Pre subgroups where significant stress-induced reinstatement was found, there may be significant effects of estrous phase.…”

Neuropeptide systems and new treatments for nicotine addiction

“…One prime example of this is the extended access nicotine self-administration procedure. In this model, rats have extended-access (21–23h) to nicotine for 1–4 days which is then followed by several days of abstinence (Cohen et al 2012; Flores et al 2016). This model leads to high levels of nicotine intake and might better model human smoking than limited access models or the non-contingent administration of nicotine.…”

Peri-adolescent drinking of ethanol and/or nicotine modulates astroglial glutamate transporters and metabotropic glutamate receptor-1 in female alcohol-preferring rats

“…A positive correlation has been associated between levels of estrogen and EtOH consumption in female humans (Frydenberg et al, 2015). In addition, female rats have been shown to have greater motivation to consume NIC or EtOH compared to female ovariectomized or male rats (Torres et al, 2014, Flores et al, 2016. The reason for using P rat model in this study is that these rats have several alcoholic phenotypes such as physiological, neurochemical and behavioral characteristics (Murphy et al, 2002, Bell et al, 2011, Bell et al, 2017.…”