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Neuropsychopharmacology. 2019 May;44(6):1141-1151. doi: 10.1038/s41386-018-0306-3. Epub 2019 Jan 7.

Insulin modulates the strong reinforcing effects of nicotine and changes in insulin biomarkers in a rodent model of diabetes.

Author information

1
Department of Psychology, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX, USA.
2
Department of Biological Sciences, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX, USA.
3
Department of Pharmaceutical Sciences, Western University of Health Sciences, Pomona, CA, USA.
4
Department of Psychology, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX, USA. lodell@utep.edu.

Abstract

This study examined whether the strong reinforcing effects of nicotine and changes in insulin biomarkers observed in diabetic rats are modulated via insulin. A model of diabetes was employed involving administration of streptozotocin (STZ), which produces hypoinsulinemia in rats. The present study included vehicle- or STZ-treated rats that received sham surgery or insulin pellets. Two weeks later, the rats were given extended access to intravenous self-administration (IVSA) of saline or nicotine. Concomitant changes in food intake, water responses, and body weight were assessed during 12 days of IVSA. After the last session, plasma levels of insulin, leptin, amylin, and glucagon-like peptide-1 (GLP-1) were assessed using Luminex® technology. In a separate cohort, phosphorylated insulin receptor substrate-2 (pIRS-2) and insulin growth factor-1 receptor β (IGF-1Rβ) were assessed in the nucleus accumbens (NAc) and ventral tegmental area (VTA) of vehicle- or STZ-treated rats that received sham surgery or an insulin pellet. STZ-treated rats displayed an increase in glucose levels, a decrease in body weight, and an increase in nicotine, food, and water intake relative to controls. STZ-treated rats also displayed a decrease in plasma insulin and leptin levels and an increase in amylin and GLP-1 levels relative to controls. Importantly, all of the STZ-induced changes in behavior and insulin biomarkers were prevented by insulin supplementation. STZ-treated rats also displayed a decrease in pIRS-2 and IGF-1Rβ in the NAc (but not VTA), an effect that was also prevented by insulin. These data suggest that insulin systems in the NAc modulate the strong reinforcing effects of nicotine in male diabetic rats.

PMID:
30647447
PMCID:
PMC6461916
[Available on 2020-05-01]
DOI:
10.1038/s41386-018-0306-3
[Indexed for MEDLINE]

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