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The Long-term Effect of Developmental Exposure to Cannabinoids During Lactation on Psychopathology

Curry, Michael and Jackson, Pamela and Willner, Jeffrey and Aspelmeier, Jeffery (2013) The Long-term Effect of Developmental Exposure to Cannabinoids During Lactation on Psychopathology. Masters thesis, Radford University.

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Abstract

Cannabinoids are the most commonly abused illicit drug during pregnancy (Moreno et al., 2003). Chronic developmental exposure to exogenous cannabinoids has been shown to alter learning and memory, and emotional regulation (O’Shea et al., 2004; Newsom & Kelly, 2007). Further research by O’Shea, McGregor, and Mallet (2006) found that repeated perinatal cannabinoid exposure from postnatal day (PD) 4 – PD 25 impaired object recognition and reduced social interaction in adulthood. However, few studies have looked at lactational exposure to cannabinoids and its effects on emotional regulation in offspring. Thirty-three dams were divided into a cannabinoid-exposed group, a food-yoked control group, or a free-fed control group. The cannabinoid exposed group received daily injections (s.c., 0.35 mg/kg) of CP 55, 940 from the second day after giving birth for 18 days (from PD 2 to PD 19 for the pups), while the control groups received comparable vehicle injections. A food-yoked control group was included because Rubino et al. (2008) found that during cannabinoid injection periods food intake, and body weight decrease, therefore it was necessary to control possible effects of malnutrition associated with decreased food intake. The food-yoked control group was allotted the same amount of food the cannabinoid exposed dam ate on that same PD day. Weight data was collected throughout the study. Behavioral testing of the offspring began on PD 77 after a 58 day washout period. Fifty-eight males were used, two from each litter, to assess emotional regulatory behaviors in adulthood. The behavioral tasks included the elevated plus-maze (EPM), the open-field emergence task, and a sucrose preference test. One male ran the EPM while the other ran the emergence task, and both ran the sucrose preference test. The data suggested that the drug-exposed animals and the yoked-control dams lost weight more quickly compared to the control group. In addition, there was a similar interaction between pup weight and drug group (the food-yoked and experimental pups gained weight at a slower pace compared to the control group). No significant results were found on the EPM, however there was a suggestion that the control animals had an increased amount of boli in the open arms compared to the yoked animals suggesting an increased anxiety in the control animals. Open-field activity measures indicated there significant difference in activity levels between the yoked and control group, where the yoked animals had increased activity. There was also an effect on anxiety where, the yoked group was less anxious than the control group. There was no significance in the data suggesting that any group spent longer in the hide box per entry. The data from the sucrose preference test reflected no evidence that lactational exposure to the cannabinoid affected anxiety (neophobia) or depression (anhedonia); all animals preferred sucrose over plain water initially and across days. The results suggested that early nutrition deficits may be a serious confound in the attribution of cognitive deficits or emotional changes to marijuana-type drug exposure during early development.

Item Type: Thesis (Masters)
Subjects: B Philosophy. Psychology. Religion > BF Psychology
Divisions: UNSPECIFIED
Depositing User: Michael Curry
Date Deposited: 04 Jun 2013 15:59
Last Modified: 04 Jun 2013 15:59
URI: http://wagner.radford.edu/id/eprint/126

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