title: Sex-dependent effects of early life inflammatory pain on sucrose intake and sucrose-associated hippocampal Arc expression in adult rats.
abstract: We hypothesize that dorsal hippocampal (dHC) neurons, which are critical for episodic memory, form a memory of a meal and inhibit the initiation of the next meal and the amount ingested during that meal. In support, we showed previously that (1) consuming a sucrose meal induces expression of the synaptic plasticity marker activity-regulated cytoskeleton-associated protein (Arc) in dHC neurons and (2) reversible inactivation of these neurons immediately following a sucrose meal accelerates the onset of the next meal and increases the size of that meal. These data suggest that hippocampal-dependent memory inhibits intake; therefore, the following experiments were conducted to determine whether hippocampal-dependent memory impairments are associated with increased intake. We reported recently that one episode of early life inflammatory pain impairs dHC-dependent memory in adult rats. The present study determined whether neonatal inflammatory pain also increases sucrose intake and attenuates sucrose-associated Arc expression. Male and female Sprague-Dawley rats were given an intraplantar injection of the inflammatory agent carrageenan (1%) on the day of birth and sucrose intake and sucrose-associated dHC Arc expression were measured in adulthood. Neonatal inflammatory pain increased sucrose intake in adult female and male rats, decreased sucrose-associated dHC Arc expression in female rats, and tended to have a similar effect on Arc expression in male rats. Neonatal inflammatory pain significantly decreased the interval between two sucrose meals in female but not in male rats. Morphine administration at the time of insult attenuated the effects of injury on sucrose intake. Collectively, these findings indicate that one brief episode of inflammatory pain on the day of birth has a long long-lasting, sex-dependent impact on intake of a palatable food in adulthood.
authors.affiliation: Neuroscience Institute, Georgia State University, P.O. Box 5030, Atlanta, GA 30302, United States. Electronic address: yokohenderson@gmail.com.
authors.forename: Yoko O
authors.initials: YO
authors.lastname: Henderson
authors.affiliation: Augusta Biomedical Research Corporation, Charlie Norwood VA Medical Center, 950 15th Street, Augusta, GA 30901, United States. Electronic address: rebeccanalloor@gmail.com.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Nalloor
authors.affiliation: Department of Pharmacology and Toxicology, Augusta University, 1120 15th Street, CB 3526, Augusta, GA 30912, United States; VA Research Service, Charlie Norwood VA Medical Center, 950 15th Street, Augusta, GA 30901, United States. Electronic address: avazdarjanova@augusta.edu.
authors.forename: Almira
authors.initials: A
authors.lastname: Vazdarjanova
authors.affiliation: Neuroscience Institute, Georgia State University, P.O. Box 5030, Atlanta, GA 30302, United States. Electronic address: amurphy@gsu.edu.
authors.forename: Anne Z
authors.initials: AZ
authors.lastname: Murphy
authors.affiliation: Neuroscience Institute, Georgia State University, P.O. Box 5030, Atlanta, GA 30302, United States; Department of Psychology, Georgia State University, P.O. Box 5030, Atlanta, GA 30302, United States. Electronic address: mbparent@gsu.edu.
authors.forename: Marise B
authors.initials: MB
authors.lastname: Parent
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D002351:Carrageenan / Q000633:toxicity; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D004435:Eating / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006624:Hippocampus / Q000378:metabolism* / Q000473:pathology; D007249:Inflammation / Q000139:chemically induced / Q000150:complications; D008297:Male; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010146:Pain / Q000209:etiology / Q000473:pathology*; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012727:Sex Characteristics; D013395:Sucrose / Q000378:metabolism*
chemical_list: D003598:Cytoskeletal Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; C092069:activity regulated cytoskeletal-associated protein; D013395:Sucrose; D002351:Carrageenan
keywords: Energy intake; Morphine; Neonatal; Palatable food; Synaptic plasticity