Maternal behavior in rats consists of active behaviors, such as retrieval and licking of pups, and quiescent nursing, including the suckling-induced kyphotic (upright, dorsally-arched) posture. Because lesions of the dorsolateral, but not of the dorsal, columns are known to prevent the suckling-induced milk-ejection reflex, we asked whether the same is true for kyphosis as well. Bilateral lesions of the dorsolateral funiculus (DLF) or dorsal columns (DC) at spinal segments C4-6 were made on day 5-8 postpartum; controls (CON) were subjected to a sham procedure. All aspects of maternal behavior and lactation were present in CON and DC dams soon after treatment. Among DLF dams, two had poor postural, ambulatory, and ingestive recovery that was associated with large lesions extending to the ventrolateral columns, while one with very small lesions continued to lactate. Of the remaining eight DLF dams, milk ejection was lost while recovery of retrieval and licking of pups occurred in all (between 1 and 4 days after surgery). All eight were quiescent for long periods in response to suckling but they did not display sustained kyphosis; rather, they nursed while prone or hunched over the pups, with little or no leg support, or while supine. Ventral trunk cutaneous sensitivity was present in all subjects. These data suggest that the dorsolateral funiculus relays both suckling-induced neuroendocrine and postural nursing reflexes that are mediated by separate supraspinal regions, hypothalamus and the ventrolateral sectors of the caudal periaqueductal gray, respectively.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Clinical Neurology
- Developmental Biology