Juvenile social experience regulates central neuropeptides relevant to emotional and social behaviors.
Stressful social experiences during early-life can increase the risk of developing neuropsychiatric disorders associated with anxiety, mood, and personality. Early neglect also alters peripheral arginine vasopression (AVP) and oxytocin (OXT). We hypothesized that a lack of social stimuli should adversely affect developmental AVP and OXT systems. To test this idea, we examined changes of central AVP- and OXT-immunoreactive (ir) cell number as well as its related behaviors in socially isolated rats. Animals were weaned at 23 days of age, divided into group- or isolation-reared conditions, and maintained for at least 2 weeks. At 38-48 days of age, animals were sacrificed for immunohistochemistry, or used for two behavioral tests: elevated plus-maze test and social recognition test. The results from immunohistochemistry showed that isolation-reared males have decreased AVP-ir cells in the paraventricular nucleus hypothalamus (PVH), medial parvicellular part, ventral zone, and that isolation-reared females have decreased OXT-ir cells in the PVH, medial parvicellular part, dorsal zone, when compared with group-reared counterparts. The results from behavioral assessment showed that isolation-reared animals have difficulty with social recognition, and that isolation-reared males, but not females, have anxiogenic profile. The present study demonstrates that post-weaning social isolation results in decrease of male AVP-ir cells and female OXT-ir cells in the PVH parvocellular divisions, and supports the idea that juvenile social environment may play a critical role in neuronal and behavioral development.
Tanaka
K
K
Department of Neurobiology and Anatomy, Kochi Medical School, Kohasu, Oko-cho, Nankoku, Kochi, Japan.
Osako
Y
Y
Yuri
K
K
D000818:Animals; D001008:Anxiety Disorders / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D001127:Arginine Vasopressin / Q000378:metabolism*; D001522:Behavior, Animal / Q000502:physiology; D002452:Cell Count; D004195:Disease Models, Animal; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D018782:Maze Learning / Q000502:physiology; D019964:Mood Disorders / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D010121:Oxytocin / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism*; D051381:Rats; D020318:Rats, Long-Evans; D012919:Social Behavior; D012934:Social Isolation / Q000523:psychology*
D001127:Arginine Vasopressin; D010121:Oxytocin