title: The responses of hypothalamic NPY and OBRb mRNA expression to food deprivation develop during the neonatal-prepubertal period and exhibit gender differences in rats.
abstract: Neuropeptide Y (NPY) is an important hypothalamic orexigenic neuropeptide that acts in the brain. It has been established that the fasting-induced up-regulation of NPY expression is mainly caused by a reduction in the activity of leptin, which is a hormone secreted by adipose tissue. We have reported that in female rats hypothalamic NPY mRNA expression does not respond to fasting during the early neonatal period, but subsequently becomes sensitive to it later in the neonatal period. In this study, we compared the developmental changes in the responses of NPY and leptin expression to fasting between male and female rats during the neonatal to pre-pubertal period. Fasting was induced by maternal deprivation during the pre-weaning period (postnatal days 10 and 20) and by food deprivation during the post-weaning period (postnatal day 30). Hypothalamic NPY mRNA expression was not affected by fasting on postnatal day 10, whereas it was increased by fasting on postnatal day 20 and 30 in both males and females. On the other hand, the serum leptin level was decreased by fasting at all examined ages in both sexes. Namely, hypothalamic NPY mRNA expression was not correlated with the reduction in the serum leptin level at postnatal day 10 in either sex. Under the fasted conditions, the hypothalamic NPY mRNA levels of the males were higher than those of the females on postnatal days 20 and 30, whereas no such differences were observed under the normal nourishment conditions. The serum leptin levels observed under the fasted conditions did not differ between males and females at any examined age. These results suggest that some hypothalamic NPY functions develop during the neonatal period and that there is no major difference between the sexes with regard to the time when NPY neurons become sensitive to fasting. They also indicate that hypothalamic NPY expression is more sensitive to under-nutrition in male rats than in female rats, at least during the pre-pubertal period.
authors.affiliation: Department of Obstetrics and Gynecology, The University of Tokushima Graduate School, Institute of Health Biosciences, 3-18-15 Kuramoto-Cho, Tokushima 770-8503, Japan. Electronic address: mat@tokushima-u.ac.jp.
authors.forename: Toshiya
authors.initials: T
authors.lastname: Matsuzaki
authors.affiliation: Department of Obstetrics and Gynecology, The University of Tokushima Graduate School, Institute of Health Biosciences, 3-18-15 Kuramoto-Cho, Tokushima 770-8503, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Iwasa
authors.affiliation: Department of Obstetrics and Gynecology, The University of Tokushima Graduate School, Institute of Health Biosciences, 3-18-15 Kuramoto-Cho, Tokushima 770-8503, Japan.
authors.forename: Altankhuu
authors.initials: A
authors.lastname: Tungalagsuvd
authors.affiliation: Department of Obstetrics and Gynecology, The University of Tokushima Graduate School, Institute of Health Biosciences, 3-18-15 Kuramoto-Cho, Tokushima 770-8503, Japan.
authors.forename: Munkhsaikhan
authors.initials: M
authors.lastname: Munkhzaya
authors.affiliation: Department of Obstetrics and Gynecology, The University of Tokushima Graduate School, Institute of Health Biosciences, 3-18-15 Kuramoto-Cho, Tokushima 770-8503, Japan.
authors.forename: Takako
authors.initials: T
authors.lastname: Kawami
authors.affiliation: Department of Obstetrics and Gynecology, The University of Tokushima Graduate School, Institute of Health Biosciences, 3-18-15 Kuramoto-Cho, Tokushima 770-8503, Japan.
authors.forename: Mikio
authors.initials: M
authors.lastname: Yamasaki
authors.affiliation: Department of Obstetrics and Gynecology, Shikoku Medical Center for Children and Adults, Senyu-cho 2-1-1, Zentsuji City, Kagawa 765-8507, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Murakami
authors.affiliation: Department of Obstetrics and Gynecology, The University of Tokushima Graduate School, Institute of Health Biosciences, 3-18-15 Kuramoto-Cho, Tokushima 770-8503, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kato
authors.affiliation: Department of Obstetrics and Gynecology, The University of Tokushima Graduate School, Institute of Health Biosciences, 3-18-15 Kuramoto-Cho, Tokushima 770-8503, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Kuwahara
authors.affiliation: Department of Reproductive Technology, Institute of Health Biosciences, The University of Tokushima Graduate School, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Yasui
authors.affiliation: Department of Obstetrics and Gynecology, The University of Tokushima Graduate School, Institute of Health Biosciences, 3-18-15 Kuramoto-Cho, Tokushima 770-8503, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Irahara
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D005260:Female; D005508:Food Deprivation / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D007031:Hypothalamus / Q000378:metabolism*; D020738:Leptin / Q000235:genetics* / Q000378:metabolism; D008297:Male; D009478:Neuropeptide Y / Q000235:genetics* / Q000378:metabolism; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012727:Sex Characteristics
chemical_list: D020738:Leptin; D009478:Neuropeptide Y; D012333:RNA, Messenger
keywords: Hypothalamus; Leptin; NPY; OBRb; Sex difference