Neonatal handling induces alteration in progesterone secretion after sexual behavior but not in angiotensin II receptor density in the medial amygdala: implications for reproductive success.
Neonatal handling affects the hypothalamus-pituitary-gonadal axis in female rats. Indeed, postnatal handling induces anovulatory estrous cycles and decreases sexual receptiveness. On the other hand, Angiotensin II (Ang II) infused into the medial amygdala (MeA) reduces sexual behavior in male and female rats. Considering this, and that gonadal steroid secretion after copulatory behavior is important for reproductive success, the purpose of the present study was to investigate whether the reduction in sexual receptiveness in neonatally handled female rats is mediated by changes in Ang II receptor density in MeA. Moreover, gonadal steroid secretion after sexual behavior was analyzed. Two groups of female Wistar rats were studied: nonhandled (pups were left undisturbed) and handled (pups were handled for 1 min once a day during the first 10 days of life). Once they were 80-85 days old in the evening of the proestrus day, sexual receptiveness was recorded and after that the animals were killed by decapitation. Trunk blood samples were collected, and plasma estradiol and progesterone were measured by radioimmunoassay. The brains were removed for Ang II receptor autoradiography in MeA. The decreased lordosis quotient in the neonatally handled group was confirmed in the present study. Neonatal handling also reduced the progesterone concentration in the plasma, but did not change the estradiol and the density of Ang II receptors in MeA. The reduced progesterone could be due to the decreased lordosis frequency of handled females. However, this decreased sexual receptiveness is not mediated by changes in Ang II receptors in MeA.
Gomes
Cármen Marilei
CM
Laboratório de Neuroendocrinologia do Comportamento, Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde (ICBS), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul (RS), Brazil.
Donadio
Márcio Vinícius Fagundes
MV
Anselmo-Franci
Janete
J
Franci
Celso Rodrigues
CR
Lucion
Aldo Bolten
AB
Sanvitto
Gilberto Luiz
GL
D000679:Amygdala / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D001345:Autoradiography; D004971:Estrus / Q000502:physiology*; D005260:Female; D006234:Handling, Psychological; D008297:Male; D011374:Progesterone / Q000097:blood / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011945:Receptors, Angiotensin / Q000096:biosynthesis*; D012726:Sexual Behavior, Animal / Q000502:physiology*
D011945:Receptors, Angiotensin; D011374:Progesterone