Effects of neonatal handling on central noradrenergic and nitric oxidergic systems and reproductive parameters in female rats.
Early-life environmental events that disrupt the mother-pup relationship may induce profound long-lasting changes on several behavioral and neuroendocrine systems. The neonatal handling procedure, which involves repeated brief maternal separations followed by experimental manipulations, reduces sexual behavior and induces anovulatory estrous cycles in female rats. On the afternoon of proestrus, neonatally handled females show a reduced surge of luteinizing hormone (LH) and an increased content of gonadotropin-releasing hormone in the medial preoptic area (MPOA). In order to detect the possible causes for the reduced ovulation and sexual behavior, the present study aimed to analyze the effects of neonatal handling on noradrenaline (NA) and nitric oxide (NO) levels in the MPOA on the afternoon of proestrus. Neonatal handling reduced MHPG (NA metabolite) levels and MHPG/NA ratio in the MPOA, indicating decreased NAergic activity. Additionally, neonatal handling decreased NO levels, as measured by the metabolites (NO(x)), nitrite and nitrate in the same period. We may conclude that the neonatal handling procedure decreased activity of the NAergic and NOergic systems in the MPOA during proestrus, which is involved in the control of LH and FSH secretion, and this may possibly explain the anovulatory estrous cycles and reduced sexual behavior of the neonatally handled female rats.
Laboratório de Neuroendocrinologia do Comportamento, Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Charlis
C
Raineki
Raphael Escorsim
RE
Szawka
Cármen Marilei
CM
Gomes
Marta Knijnik
MK
Lucion
Jaqueline
J
Barp
Adriane
A
Belló-Klein
Celso Rodrigues
CR
Franci
Janete Aparecida
JA
Anselmo-Franci
Gilberto Luiz
GL
Sanvitto
Aldo Bolten
AB
Lucion
D000818:Animals; D000831:Animals, Newborn; D005260:Female; D006234:Handling, Psychological; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism*; D011247:Pregnancy; D011301:Preoptic Area / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012098:Reproduction / Q000502:physiology*; D012726:Sexual Behavior, Animal / Q000502:physiology
D009569:Nitric Oxide; D009638:Norepinephrine