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 (NOx), 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.

Keywords:
Neonatal handling, Nitric oxide, Noradrenaline, Estradiol, Sexual behavior, Ovulation, Medial preoptic area, Luteinizing hormone, Follicle-stimulating hormone
1.
Meerlo P, Horvath KM, Nagy GM, Bohus B, Koolhaas JM: The influence of postnatal handling on adult neuroendocrine and behavioural stress reactivity. J Neuroendocrinol 1999;11:925–933.
2.
Francis DD, Caldji C, Champagne F, Plotsky PM, Meaney MJ: The role of corticotrophin-releasing factor-norepinephrine systems in mediating the effects of early experience on the development of behavioral and endocrine responses to stress. Biol Psychiatry 1999;46:1153–1166.
3.
Levine S: Developmental determinants of sensitivity and resistance to stress. Psychoneuroendocrinology 2005;30:939–946.
4.
Núñez JF, Ferré P, Escorihuela RM, Tobeña A, Fernádez-Teruel A: Effects of postnatal handling of rats on emotional, HPA-axis, and prolactin reactivity to novelty and conflict. Physiol Behav 1996;60:1355–1359.
5.
Padoin MJ, Cadore LP, Gomes CM, Barros HMT, Lucion AB: Long-lasting effects of neonatal stimulation on the behavior of rats. Behav Neurosci 2001;115:1332–1340.
6.
Plotsky PM, Meaney MJ: Early, postnatal experience alters hypothalamic corticotropin-releasing factor (CRF) mRNA, median eminence CRF content and stress-induced release in adult rats. Mol Brain Res 1993;18:195–200.
7.
Liu D, Caldji C, Sharma S, Plotsky PM, Meaney MJ: Influence of neonatal rearing conditions on stress-induced adrenocorticotropin responses and norepinephrine release in the hypothalamic paraventricular nucleus. J Neuroendocrinol 2000;12:5–12.
8.
Severino GS, Fossati IAM, Padoin MJ, Gomes CM, Trevizan L, Sanvitto GL, Franci CR, Anselmo-Franci JA, Lucion AB: Effect of neonatal handling on the behavior and prolactin stress response in male and female rats at various ages and estrous cycle phases of females. Physiol Behav 2004;81:489–498.
9.
Gomes CM, Donadio MVF, Anselmo-Franci JA, Franci CR, Lucion AB, Sanvitto GL: 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. Life Sci 2006;78:2867–2871.
10.
Mazaro R, Lamano-Carvalho TL: Prolonged deleterious effects of neonatal handling on reproductive parameters of pubertal male rats. Reprod Fert Dev 2006;18:497–500.
11.
Gomes CM, Frantz PJ, Sanvitto GL, Anselmo-Franci JA, Lucion AB: Neonatal handling induces anovulatory estrous cycles in rats. Braz J Med Biol Res 1999;32:1239–1242.
12.
Gomes CM, Raineki C, Ramos PP, Severino GS, Helena CVV, Anselmo-Franci JA, Franci CR, Sanvitto GL, Lucion AB: Neonatal handling and reproductive function in female rats. J Endocrinol 2005;184:435–445.
13.
Freeman ME: The neuroendocrine control of the ovarian cycle of the rat; in Knobil E, Neill JD (eds): The Physiology of Reproduction. New York, Raven Press, 1994, pp 613–657.
14.
Herbison AE: Multimodal influence of estrogen upon gonadotropin-releasing hormone neurons. Endocr Rev 1998;19:302–330.
15.
McCann SM, Mastronardi C, Walczewska A, Karanth S, Rettori V, Yu WH: The role of nitric oxide in reproduction. Braz J Med Biol Res 1999;32:1367–1379.
16.
Petersen SL, Ottem EN, Carpenter CD: Direct and indirect regulation of gonadotropin-releasing hormone neurons by estradiol. Biol Reprod 2003;69:1771–1778.
17.
Anselmo-Franci JA, Franci CR, Krulich L, Antunes-Rodrigues J, McCann SM: Locus coeruleus lesions decrease norepinephrine input into the medial preoptic area and medial basal hypothalamus and block LH, FSH and prolactin preovulatory surge. Brain Res 1997;767:289–296.
18.
Szawka RE, Franci CR, Anselmo-Franci JA: Noradrenaline release in the medial preoptic area during the rat oestrous cycle: temporal relationship with plasma secretory surges of prolactin and luteinizing hormone. J Neuroendocrinol 2007;19:374–382.
19.
Helena CVV, Franci CR, Anselmo-Franci JA: Luteinizing hormone and luteinizing hormone-releasing hormone secretion is under locus coeruleus control in female rats. Brain Res 2002;955:245–252.
20.
Martins-Afférri MP, Ferreira-Silva IA, Franci CR, Anselmo-Franci JA: LHRH release depends on locus coeruleus noradrenergic inputs to the medial preoptic area and median eminence. Brain Res Bull 2003;61:521–527.
21.
Shughrue PJ, Lane MV, Merchenthaler I: Comparative distribution of estrogen receptor-α and -β mRNA in the rat central nervous system. J Comp Neurol 1997;388:507–525.
22.
Helena CVV, Poletini MO, Sanvitto GL, Hayashi S, Franci CR, Anselmo-Franci JA: Changes in α-estradiol receptor and progesterone receptor expression in the locus coeruleus and preoptic area throughout the rat estrous cycle. J Endocrinol 2006;188:155–165.
23.
Swanson LW, Hartman BK: The central adrenergic system. An immunofluorescence study of the location of cell bodies and their efferent connections in the rat utilizing dopamine-beta-hydroxylase as a marker. J Comp Neurol 1975;163:467–505.
24.
Grzanna R, Molliver ME: The locus coeruleus in the rat: an immunocytochemical delineation. Neuroscience 1980;5:21–40.
25.
Aston-Jones G, Shipley MT, Grzanna R: The locus coeruleus, A5 and A7 noradrenergic cell groups; in Paxinos G (ed): The Rat Nervous System. San Diego, Academic Press, 1995, pp 183–213.
26.
Terasawa E, Krook C, Hei DL, Gearing M, Schultz NJ, Davis GA: Norepinephrine is a possible neurotransmitter stimulating pulsatile release of luteinizing hormone releasing hormone in the rhesus monkey. Endocrinology 1988;123:1808–1816.
27.
Gitler MS, Barraclough CA: Locus coeruleus (LC) stimulation augments LHRH release induced by medial preoptic stimulation: evidence that the major LC stimulatory component enters contralaterally into the hypothalamus. Brain Res 1987;422:1–10.
28.
Franci JA, Antunes-Rodrigues J: Effects of locus coeruleus lesion on luteinizing hormone secretion under different experimental conditions. Neuroendocrinology 1985;41:44–51.
29.
McCann SM, Mastronardi C, Walczewska A, Karanth S, Rettori V, Yu WH: The role of nitric oxide (NO) in control of LHRH release that mediates gonadotropin release and sexual behavior. Curr Pharm Des 2003;9:381–390.
30.
Nelson RJ, Kriegsfeld LJ, Dawson VL, Dawson TM: Effects of nitric oxide on neuroendocrine function and behavior. Front Neuroendocrinol 1997;18:463–491.
31.
Calka J: The role of nitric oxide in the hypothalamic control of LHRH and oxytocin release, sexual behavior an aging of LHRH and oxytocin neurons. Folia Histochem Cytochem 2006;44:3–12.
32.
Bhat GK, Mahesh VB, Lamar CA, Ping L, Aguan K, Brann DW: Histochemical localization of nitric oxide neurons in the hypothalamus: association with gonadotropin-releasing hormone neurons and co-localization with N-methyl-D-aspartate receptors. Neuroendocrinology 1995;62:187–197.
33.
Herbison AE, Simonian SX, Norris PJ, Emson PC: Relationship of neuronal nitric oxide synthase immunoreactivity to GnRH neurons in the ovariectomized and intact female rat. J Neuroendocrinol 1996;8:73–82.
34.
Rettori V, Belova N, Dees WL, Nyberg CL, Gimeno M, McCann SM: Role of nitric oxide in the control of luteinizing hormone-releasing hormone release in vivo and in vitro. Proc Nat Acad Sci USA 1993;90:10130–10134.
35.
Moretto M, López FJ, Negro-Vilar A: Nitric oxide regulates luteinizing hormone-releasing hormone secretion. Endocrinology 1993;133:2399–2402.
36.
Bonavera JJ, Sahu A, Kalra PS, Kalra SP: Evidence in support of nitric oxide (NO) involvement in the cyclic release of prolactin and LH surge. Brain Res 1994;660:175–179.
37.
Mani SK, Allen JMC, Rettori V, McCann SM, O’Malley BW, Clark JH: Nitric oxide mediates sexual behavior in female rats. Proc Nat Acad Sci USA 1994;91:6468–6472.
38.
Lucion AB, Pereira FM, Winkelman EC, Sanvitto GL, Anselmo-Franci JA: Neonatal handling reduces the number of cells in the locus coeruleus of rats. Behav Neurosci 2003;17:894–903.
39.
Sodersten P, Hansen S: Effects of estradiol and progesterone on the induction and duration of sexual receptivity in cyclic female rats. J Endocrinol 1977;74:477–485.
40.
Poletini MO, Szawka RE, Marcon RMF, Veiga MD, Franci CR, Anselmo-Franci JA: A method to study preovulatory surge of gonadotropins. Brain Res Prot 2003;12:41–48.
41.
Harms PG, Ojeda SR: A rapid and simple procedure for chronic cannulation of the rat jugular vein. J Appl Physiol 1974;36:391–392.
42.
Lima FB, Szawka RE, Anselmo-Franci JA, Franci CR: Pargyline effects on luteinizing hormone secretion throughout the rat estrous cycle: correlation with serotonin, catecholamines and nitric oxide in the medial preoptic area. Brain Res 2007;1142:37–45.
43.
Szawka RE, Helena CV, Rodovalho GV, Monteiro PM, Franci CR, Anselmo-Franci JA: Locus coeruleus norepinephrine regulates the surge of prolactin during oestrus. J Neuroendocrinol 2005;17:639–648.
44.
Palkovits M: Isolated removal of hypothalamic or other brain nuclei of the rat. Brain Res 1973;59:449–450.
45.
Paxinos G, Watson C: The Rat Brain in Stereotaxic Coordinates. New York, Academic Press, 1998.
46.
Bradford MM: A rapid and sensitive method for quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 1976;72:248–254.
47.
Flodes A, Meek JL: Occurrence and localization of brain phenolsulfotransferase. J Neurochem 1974;23:303–307.
48.
Lookingland KJ, Ireland LM, Gunnet JW, Manzanares J, Tian Y, Moore KE: 3-Methoxy-4-hydroxyphenylethyleneglycol concentrations on discrete hypothalamic nuclei reflect the activity of noradrenergic neurons. Brain Res 1991;559:82–88.
49.
Granger DL, Anstey NM, Miller WC, Weinberg JB: Measuring nitric oxide production in human clinical studies. Methods Enzymol 1999;301:49–61.
50.
Prevot V, Bouret S, Stefano GB, Beauvillain JC: Median eminence nitric oxide signaling. Brain Res Rev 2000;34:27–41.
51.
Knauf C, Prevot V, Stefano GB, Mortreux G, Beauvillain JC, Croix D: Evidence for a spontaneous nitric oxide release from the rat median eminence: influence on gonadotropin-releasing hormone release. Endocrinology 2001;142:2343–2350.
52.
Selvage DJ, Johnston CA: Interaction between norepinephrine, oxytocin, and nitric oxide in the stimulation of gonadotropin-releasing hormone release from proestrous rat basal hypothalamus explants. J Neuroendocrinol 2004;16:819–824.
53.
Anselmo-Franci JA, Rocha-Barros VM, Franci CR, McCann SM: Locus ceruleus lesions block pulsatile LH release in ovariectomized rats. Brain Res 1999;833:86–92.
54.
Okamura H, Yokosuka M, McEwen BS, Hayashi S: Colocalization of NADPH-diaphorase and estrogen receptor immunoreactivity in the rat ventromedial hypothalamic nucleus: stimulatory effect of estrogen on NADPH-diaphorase activity. Endocrinology 1994;135:1705–1708.
55.
Ceccatelli S: Expression and plasticity of NO synthase in the neuroendocrine system. Brain Res Bull 1997;44:533–538.
56.
Dufourny L, Skinner DC: Influence of estradiol on NADPH diaphorase/neuronal nitric oxide synthase activity and colocalization with progesterone or type II glucocorticoid receptors in ovine hypothalamus. Biol Reprod 2002;67:829–836.
57.
González-Flores O, Etgen AM: The nitric oxide pathway participates in estrous behavior induced by progesterone and some of its ring A-reduced metabolites. Horm Behav 2004;45:50–57.
58.
Panzica GC, Viglietti-Panzica C, Sica M, Gotti S, Martini M, Pinos H, Carrillo B, Collado P: Effects of gonadal hormones on central nitric oxide producing systems. Neuroscience 2006;138:987–995.
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