(23) The impact of cycling gonadal hormones on ethanol preference and affective responses in female mice

     Female hormones differ based on the females’ reproductive status. In non-pregnant females, steroid and peptide hormones released from the hypothalamus, pituitary gland, and ovaries facilitate ovum maturation,... [ view full abstract ]

     Female hormones differ based on the females’ reproductive status. In non-pregnant females, steroid and peptide hormones released from the hypothalamus, pituitary gland, and ovaries facilitate ovum maturation, initiate ovulation and prepare for pregnancy. These hormone levels fluctuate predictably over a given time period, forming the 28-day menstrual cycle in primates (including humans) and the 4-day estrus cycle in rodents. In rodents, estrus status influences females’ performance on certain behavioral assays, including response to drugs of abuse, and alter the sensitivity of neural circuits involved in reward and motivation, including the mesolimbic dopamine system. Unfortunately, a significant sex bias exists in biomedical literature using animal models, due in part to a concern over potential variability attributable to changing hormone levels. The present study investigated the impact of estrus stage on a number of behaviors, including ethanol preference, anxiety and despair-like behavior. Subjects were female mice (n=26) who were participating in an ethanol-drinking study (see Blake et al., 2017). Females’ estrus stage was identified twice: (a) 12hrs after being chronically exposed to ethanol and undergoing an ethanol preference test, and (b) 12hrs after a series of forced swim tests (a stressor and an indicator of despair-like behavior), anxiety test on an elevated plus-maze, and ethanol preference test. Estrus cycle stage was identified via vaginal cytology. Samples were collected non-invasively, stained with 0.1% crystal violet solution, and air-dried. Cell morphology was identified via light microscopy and compared to reference images. Preliminary results suggest that behavioral performance was impacted by estrus stage. This study was designed and conducted by PSYC359 students in Spring 2017.