Spinal pathway of the milk-ejection reflex in the rat

Area of Science:

• Neuroscience
• Physiology
• Reproductive Biology

Background:

• The milk-ejection reflex is crucial for lactation.
• Spinal cord pathways mediating this reflex are not fully understood.

Purpose of the Study:

• To investigate the role of specific spinal cord tracts in the milk-ejection reflex.
• To determine the effects of spinal cord lesions on suckling-induced milk ejection.

Main Methods:

• Lactating rats underwent surgical lesions of specific spinal cord funiculi (dorsal, lateral, dorsal and ventral).
• Milk ejection was assessed via intramammary pressure recordings during suckling.
• Sham-operated rats served as controls.

Main Results:

• Bilateral lesions of the lateral funiculus abolished milk ejection.
• Dorsal funiculus lesions or combined dorsal and ventral funiculus lesions did not significantly alter milk ejection incidence compared to controls.
• Unilateral lateral funiculus lesions impaired ipsilateral suckling-induced milk ejection but not contralateral or bilateral suckling.

Conclusions:

• The lateral funiculus of the spinal cord is essential for mediating the milk-ejection reflex.
• Dorsal and ventral funiculi are not critical for this reflex pathway.
• Asymmetrical sensory input can influence reflex efficacy.