Effects of multiple daily nicotine administrations on pre- and post-nicotine circadian activity episodes in rats.

Abstract

Administration of a single daily dose of nicotine has been shown to entrain circadian activity episodes both preceding and following the administration time that persist for several days after drug administration ceases. The present study tested the effects of multiple daily nicotine administrations on circadian activity episodes in adult female rats kept under constant light and rate-limited food access. Eight rats received 7 separate 7-day nicotine injection series, each followed by a 3-day test phase without injections. Subcutaneous nicotine was administered once a day during the 1st and 7th series, twice daily during the 2nd and 6th series, three times daily during the 3rd and 5th series, and four times daily during the 4th series. To control the cumulative daily dose throughout the study, 1.0 mg/kg nicotine was evenly divided among the injections within a single day. Pre- and post-administration effects of nicotine declined across the day, and significant entrainment of both pre- and post-nicotine episodes occurred for only one daily injection in each series. Additionally, post-nicotine episodes showed a different dose-response curve than the pre-nicotine episodes: post-nicotine wheel turns increased as the dose decreased, whereas pre-nicotine wheel turns remained relatively constant as the dose changed. These results provide evidence that nicotine-induced circadian entrainment to a single administration time does occur when the drug is administered multiple times a day, and pre- and post-nicotine circadian episodes are mediated at least partially by separate mechanisms.

Adult consequences of repeated nicotine vapor inhalation in adolescent rats

“…The effect of nicotine, delivered by s.c. injection or vapor inhalation, on wheel activity is similar to a suppressive effect of 0.4 mg/kg nicotine, s.c., injection on wheel activity (Bryson et al, 1981). Another report found ∼0.25 mg/kg, s.c. to be the peak of an inverted-U dose response for increased wheel activity in female Sprague-Dawley rats (Gillman et al, 2010), again showing that nicotine can either increase or decrease rodent activity depending on dose, assay and other factors.…”

Increased expression of plasma hsa‐miR‐181a in male patients with heroin addiction use disorder

“…Age, daily dose, and usage are important factors affecting prognosis of drug addiction. 58,59 In this study, we focused on the relationship between hsa-miR-181a and these factors. This discrepancy could be attributed to different regulatory mechanisms in various drug addictions.…”

“…Interestingly, we found the potential diagnostic value of has‐miR‐181a in heroin addiction (Figure 3). Age, daily dose, and usage are important factors affecting prognosis of drug addiction 58,59 . In this study, we focused on the relationship between hsa‐miR‐181a and these factors.…”

Nicotinic Regulation of Energy Homeostasis

“…When nicotine is administered chronically at fixed times of the day, increased wheel running is observed in the preinjection phase and persists for at least two days after cessation of the treatment (Gillman et al, 2008). When nicotine is administered multiple times a day, nicotine-elicited potentiation of wheel running is observed for a single injection/day and declines for the other times of administration (Gillman et al, 2010).…”