Social enrichment alters the response of brain leukocytes to chemotherapy and tumor development in aged mice.

Aging is a risk factor for the development of breast cancer. Foundational science studies have supported associations among neuroinflammation, breast cancer, and chemotherapy, but to date, these associations are based on studies using young adult rodents. The current study examined the neuroinflammatory effects of chemotherapy in aged, tumor-naïve and tumor-bearing mice with or without social enrichment.

Mammary Tumors Induce Central Pro-inflammatory Cytokine Expression, but Not Behavioral Deficits in Balb/C Mice.

Breast cancer survivors are more likely to develop mood disorders and cognitive deficits than women in the general population. Previous studies suggest that peripheral tumors elicit central pro-inflammatory cytokine production, in turn leading to depression and cognitive deficits. In the current study, two cohorts of female Balb/C mice received bilateral orthotopic injections of syngeneic 67NR, 4T07, or 4T1cells (1 × 10 cells per injection) to induce mammary tumors.

Time-of-Day Dictates Transcriptional Inflammatory Responses to Cytotoxic Chemotherapy.

Many cytotoxic chemotherapeutics elicit a proinflammatory response which is often associated with chemotherapy-induced behavioral alterations. The immune system is under circadian influence; time-of-day may alter inflammatory responses to chemotherapeutics. We tested this hypothesis by administering cyclophosphamide and doxorubicin (Cyclo/Dox), a common treatment for breast cancer, to female BALB/c mice near the beginning of the light or dark phase.