Effects of mastectomy and vagotomy on grooming behavior of the rat: possible involvement of prolactin.

Surgical interventions such as unilateral mastectomy or vagotomy affect plasma prolactin (PRL) levels. Right-side mastectomized rats exhibiting high levels of plasma PRL showed increased grooming behavior. Left-side mastectomized rats with low levels of plasma PRL performed poor grooming activity. Bilateral mastectomy that caused a slight increase in plasma PRL levels was followed by enhanced grooming behavior. Both left and right vagotomy resulted in a significant increase in plasma PRL levels. However, only left-side vagotomized rats exhibited increased levels of grooming behavior, while no difference between right-side vagotomized rats and controls occurred. It is possible that changes in plasma PRL levels induced by surgical interventions affect grooming activity of the rat. However, the hypothesis that the integrity of peripheral organs is important for the display of grooming behavior cannot be ruled out.