Role of the Midbrain Periaqueductal Gray in Maternal Nurturance and Aggression: c-fos and Electrolytic Lesion Studies in Lactating Rats

摘要: The upright crouched, or kyphotic, nursing posture of lactating rats is dependent on suckling stimulation from pups. Because the neuroanatomical connections periaqueductal gray (PAG) and its sensorimotor integration analogous lordosis displayed by sexually receptive female rats, possible role PAG in kyphosis was investigated using c-fos immunocytochemistry electrolytic lesions. Lactating interacting with a litter pups showed greater Fos-immunoreactive nuclei lateral ventrolateral caudal (cPAGl,vl) compared dams receiving nonsuckling somatosensory, distal, no In contrast, this pattern not evident rostral PAG, where highest Fos levels occurred nonsuckled dams, five other brainstem sites either group differences (peripeduncular, dorsal raphe, pontine nuclei) negligible (ventral tegmental area, spinal trigeminal nuclei). After bilateral lesions cPAGl,vl during gestation day 7 postpartum, active maternal behaviors, such as retrieval licking pups, total time were essentially normal. Kyphotic nursing, however, reduced 85%, prone supine postures increased substantially, 24 hr weight gains reduced, particularly early lactation (by 26%). Furthermore, lesioned attacked strange male twice often controls did, which suggestive fearfulness. These results extend known roles reproductive defensive behaviors to postural control suckling-induced kyphotic modulation aggression.