In this paper we surveyed molecular changes in the hypothalamus in chronically stressed rats.

Stress is generally a beneficial experience that motivates an organism to action to overcome the stressful challenge. In particular situations, when stress becomes chronic might be harmful and devastating. The hypothalamus is a critical coordinator of stress and the metabolic response; therefore, disruptions in this structure may be a significant cause of the hormonal and metabolic disturbances observed in depression. Chronic stress induces adverse changes in the morphology of neural cells that are often associated with a deficiency of neurotrophic factors (NTFs); additionally, many studies indicate that insufficient NTF synthesis may participate in the pathogenesis of depression.

We found that: 1) Chronic mild stress leads to behavioral disturbances (lowered sucrose consumption that could be interpreted as anhedonia). 2) Chronic mild stress, but not prenatal stress alters NGF breakdown in hypothalamus. 3) Matrix metalloproteinases are involved in the nerve growth factor decomposition. 4) Chronic stress enhanced the degradation of m-NGF and the accumulation of pro-NGF.