Estrous cycle influences the expression of neuronal nitric oxide synthase in the hypothalamus and limbic system of female mice - PubMed (original) (raw)
Estrous cycle influences the expression of neuronal nitric oxide synthase in the hypothalamus and limbic system of female mice
Monica Sica et al. BMC Neurosci. 2009.
Abstract
Background: Nitric oxide plays an important role in the regulation of male and female sexual behavior in rodents, and the expression of the nitric oxide synthase (NOS) is influenced by testosterone in the male rat, and by estrogens in the female. We have here quantitatively investigated the distribution of nNOS immunoreactive (ir) neurons in the limbic hypothalamic region of intact female mice sacrificed during different phases of estrous cycle.
Results: Changes were observed in the medial preoptic area (MPA) (significantly higher number in estrus) and in the arcuate nucleus (Arc) (significantly higher number in proestrus). In the ventrolateral part of the ventromedial nucleus (VMHvl) and in the bed nucleus of the stria terminalis (BST) no significant changes have been observed. In addition, by comparing males and females, we observed a stable sex dimorphism (males have a higher number of nNOS-ir cells in comparison to almost all the different phases of the estrous cycle) in the VMHvl and in the BST (when considering only the less intensely stained elements). In the MPA and in the Arc sex differences were detected only comparing some phases of the cycle.
Conclusion: These data demonstrate that, in mice, the expression of nNOS in some hypothalamic regions involved in the control of reproduction and characterized by a large number of estrogen receptors is under the control of gonadal hormones and may vary according to the rapid variations of hormonal levels that take place during the estrous cycle.
Figures
Figure 1
A-F. Six drawings corresponding to coronal sections through a representative male mouse hypothalamus and limbic system arranged from the most rostral (A – preoptic area) to the most caudal (F – paraventricular region). Grey dots illustrate the distribution of nNOS-ir cell bodies. Nuclei are delineated according to the mouse brain atlas [69]. aca = anterior commissure, anterior; acp = anterior commissure, posterior; Arc = arcuate nucleus; AVPe = anteroventral periventricular nucleus; BSTmpm = bed nucleus of the stria terminalis, posteromedial subdivision; BSTmv = bed nucleus of the stria terminalis, ventromedial subdivision; DM = dorsomedial hypothalamic nucleus; f = fornix; LA = lateroanterior hypothalamic nucleus; mfb = medial forebrain bundle; ME = median eminence; MPA = medial preoptic area; opt = optic tract; ox = optic chiasm; PaAP = anterior parvicellular part of PVN; PaLM = lateral magnocellular part of PVN; PaV = ventral part of PVN; PVN = paraventricular nucleus; SCh = suprachiasmatic nucleus; VMH = ventromedial nucleus; VMHdm = ventromedial nucleus, dorsomedial part; VMHc = ventromedial nucleus, central part; VMHvl = ventromedial nucleus, ventrolateral part; * = third ventricle.
Figure 2
A-F. Six drawings corresponding to coronal sections through a representative male mouse hypothalamus and limbic system arranged from the most rostral (A – paraventricular region) to the most caudal (F – posterior region). Grey dots illustrate the distribution of nNOS-ir cell bodies. Nuclei are delineated according to the mouse brain atlas [69]. aca = anterior commissure, anterior; acp = anterior commissure, posterior; Arc = arcuate nucleus; AVPe = anteroventral periventricular nucleus; BSTmpm = bed nucleus of the stria terminalis, posteromedial subdivision; BSTmv = bed nucleus of the stria terminalis, ventromedial subdivision; DM = dorsomedial hypothalamic nucleus; f = fornix; LA = lateroanterior hypothalamic nucleus; mfb = medial forebrain bundle; ME = median eminence; MPA = medial preoptic area; opt = optic tract; ox = optic chiasm; PaAP = anterior parvicellular part of PVN; PaLM = lateral magnocellular part of PVN; PaV = ventral part of PVN; PVN = paraventricular nucleus; SCh = suprachiasmatic nucleus; VMH = ventromedial nucleus; VMHdm = ventromedial nucleus, dorsomedial part; VMHc = ventromedial nucleus, central part; VMHvl = ventromedial nucleus, ventrolateral part; * = third ventricle.
Figure 3
Micrographs illustrating the nuclei considered in the experiment. Boxed areas represent the regions in which nNOS-ir cells were quantified. Scale bar: 200 μm.
Figure 4
Distribution of nNOS-ir neurons within the mouse medial preoptic area (MPA). Comparison among females in different stages of the cycle (estrus and diestrus) and males. Scale bar: 150 μm. The histogram reports the quantitative differences in the number of nNOS-ir cells (mean ± standard error). * = p < 0.05 in comparison to males; °° = p < 0.01 in comparison to estrus female.
Figure 5
Distribution of weakly stained (clear) nNOS-ir neurons within the mouse bed nucleus of the stria terminalis, ventromedial subdivision (BSTmv). Comparison among females and males. Scale bar: 150 μm. The histogram reports the quantitative differences in the number of nNOS-ir cells (mean ± standard error). * = p < 0.05 in comparison to males.
Figure 6
Distribution of nNOS-ir neurons within the mouse arcuate nucleus (Arc). Comparison among females in different stages of the cycle (proestrus and diestrus) and males. Scale bar: 150 μm. The histogram reports the quantitative differences in the number of nNOS-ir cells (mean ± standard error). * = p < 0.05 in comparison to males; °° = p < 0.01 in comparison to estrus female; ^^ = p < 0.01 in comparison to proestrus females.
Figure 7
Distribution of nNOS-ir neurons within the mouse paraventricular nucleus (PVN). Comparison among females in different stages of the cycle (proestrus and metestrus) and males. Scale bar: 150 μm. The histogram reports the mean number of nNOS-ir cells (mean ± standard error) per each examined stage.
References
- Moncada S, Palmer RM, Higgs EA. Nitric oxide: physiology, pathophysiology, and pharmacology. Pharmacol Rev. 1991;43:109–142. - PubMed
- Moodley YP. The role of inducible nitric oxide in health and disease. Curr Diagnostic Pathol. 2002;8:297–304. doi: 10.1016/S0968-6053(02)90131-6. - DOI