Previous reports about the rat ovary have shown that cold stress promotes ovarian morphological alterations related to a polycystic ovary (PCO) condition through activation of the ovarian sympathetic nerves. Because the noradrenergic nucleus locus coeruleus (LC) is activated by cold stress and synaptically connected to the preganglionic cell bodies of the ovarian sympathetic pathway, this study aimed to evaluate the LC's role in cold stress-induced PCO in rats. Ovarian morphology and endocrine and sympathetic functions were evaluated after 8 wk of chronic intermittent cold stress (4 C, 3 h/d) in rats with or without LC lesion. The effect of acute and chronic cold stress upon the LC neuron activity was confirmed by Fos protein expression in tyrosine hydroxylase-immunoreactive neurons. Cold stress induced the formation of follicular cysts, type III follicles, and follicles with hyperthecosis alongside increased plasma estradiol and testosterone levels, irregular estrous cyclicity, and reduced ovulation. Considering estradiol release in vitro, cold stress potentiated the ovarian response to human chorionic gonadotropin. Ovarian norepinephrine (NE) was not altered after 8 wk of stress. However, LC lesion reduced NE activity in the ovary of cold-stressed rats, but not in controls, and prevented all the cold stress effects evaluated. Cold stress increased the number of Fos/tyrosine hydroxylase-immunoreactive neurons in the LC, but this effect was more pronounced for acute stress as compared with chronic stress. These results show that cold stress promotes PCO in rats, which apparently depends on ovarian NE activity that, under this condition, is regulated by the noradrenergic nucleus LC.

Neonatal handling induces anovulatory estrous cycles and decreases sexual receptivity in female rats. The synchronous secretion of hormones from the gonads (estradiol (E 2 ) and progesterone (P)), pituitary (luteinizing (LH) and follicle-stimulating (FSH) hormones) and hypothalamus (LH-releasing hormone (LHRH)) are essential for the reproductive functions in female rats. The present study aimed to describe the plasma levels of E 2 and P throughout the estrous cycle and LH, FSH and prolactin (PRL) in the afternoon of the proestrus, and the LHRH content in the medial preoptic area (MPOA), median eminence (ME) and medial septal area (MSA) in the proestrus, in the neonatal handled rats. Wistar pup rats were handled for 1 min during the first 10 days after delivery (neonatal handled group) or left undisturbed (nonhandled group). When they reached adulthood, blood samples were collected through a jugular cannula and the MPOA, ME and MSA were microdissected. Plasma levels of the hormones and the content of LHRH were determined by RIA. The number of oocytes counted in the morning of the estrus day in the handled rats was significantly lower than in the nonhandled ones. Neonatal handling reduces E 2 levels only on the proestrus day while P levels decreased in metestrus and estrus. Handled females also showed reduced plasma levels of LH, FSH and PRL in the afternoon of the proestrus. The LHRH content in the MPOA was significantly higher than in the nonhandled group. The reduced secretion of E 2 , LH, FSH and LHRH on the proestrus day may explain the anovulatory estrous cycle in neonatal handled rats. The reduced secretion of PRL in the proestrus may be related to the decreased sexual receptiveness in handled females. In conclusion, early-life environmental stimulation can induce long-lasting effects on the hypothalamus-pituitary-gonad axis .

Design: Subjects were studied at baseline and during local leg infusion of insulin alone (control, n ϭ 7) or insulin plus the nitric oxide synthase inhibitor NG-monomethyl-L-arginine (L-NMMA, n ϭ 7) to prevent insulin-induced vasodilation. Methods: We measured skeletal muscle protein metabolism with stable isotope tracers, blood flow with indocyanine green, capillary recruitment with contrast enhanced ultrasound, glucose metabolism with stable isotope tracers, and phosphorylation of proteins associated with insulin (Akt) and amino acid-induced mammalian target of rapamycin(mTOR) complex 1 (mTORC1) signaling (mTOR, S6 kinase 1, and eukaryotic initiation factor 4Ebinding protein 1) with Western blot analysis. Results: No basal differences between groups were detected. During insulin infusion, blood flow and capillary recruitment increased in the control (P Ͻ 0.05) group only; Akt phosphorylation and glucose uptake increased in both groups (P Ͻ 0.05), with no group differences; and mTORC1 signaling increased more in control (P Ͻ 0.05) than in L-NMMA. Phenylalanine net balance increased (P Ͻ 0.05) in both groups, but with opposite mechanisms: increased protein synthesis (basal, 0.051 Ϯ 0.006%/h; insulin, 0.077 Ϯ 0.008%/h; P Ͻ 0.05) with no change in proteolysis in control and decreased proteolysis (P Ͻ 0.05) with no change in synthesis (basal, 0.061 Ϯ 0.004%/h; insulin, 0.050 Ϯ 0.006%/h; P value not significant) in L-NMMA. Conclusions: Endothelial-dependent vasodilation and the consequent increase in nutritive flow and mTORC1 signaling, rather than Akt signaling, are fundamental mechanisms by which insulin stimulates muscle protein synthesis in humans. Additionally, these data underscore that insulin modulates skeletal muscle proteolysis according to its effects on nutritive flow. Dihydrotestosterone Suppresses Foam Cell Formation and Attenuates Atherosclerosis DevelopmentYang Qiu, Toshihiko Yanase, Haidi Hu, Tomoko Tanaka, Yoshihiro Nishi, Min Liu, Katsuo Sueishi, Tatsuya Sawamura, and Hajime Nawata ABSTRACTThe role of testosterone in atherosclerosis remains unclear because it is aromatized to estrogen. We investigated the effect of the nonaromatized natural androgen 5␣-dihydrotestosterone (DHT) on the rabbit atherogenesis in relation to the proatherogenic molecule lectin-like oxidized-low-density lipoprotein receptor-1 (LOX-1) and its downstream molecules. Thirty-nine male New Zealand white rabbits were divided into four groups: 1) noncastrated group with normal chow diet (n ϭ 6); 2) noncastrated group with high-cholesterol diet (HCD) (n ϭ 10); 3) castrated group with HCD plus sc placebo pellet (n ϭ 11); and 4) castrated group with HCD plus sc 150 mg DHT pellet (n ϭ 12). Implantation of sc DHT or placebo pellet was performed at the time of castration. After castration or sham operation, the rabbits were fed the HCD for 8 wk, and plaque areas were assessed in the entire aorta. The HCD-induced increase in plaque area, which was most aggravated in the castration plus placebo group, was attenuated in the castration p...

The role of norepinephrine (NE) in regulation of LH is still controversial. We investigated the role played by NE in the positive feedback of estradiol and progesterone. Ovarian-steroid control over NE release in the preoptic area (POA) was determined using microdialysis. Compared with ovariectomized (OVX) rats, estradiol-treated OVX (OVX+E) rats displayed lower release of NE in the morning but increased release coincident with the afternoon surge of LH. OVX rats treated with estradiol and progesterone (OVX+EP) exhibited markedly greater NE release than OVX+E rats, and amplification of the LH surge. The effect of NE on LH secretion was confirmed using reverse microdialysis. The LH surge and c-Fos expression in anteroventral periventricular nucleus neurons were significantly increased in OVX+E rats dialyzed with 100 nm NE in the POA. After Fluoro-Gold injection in the POA, c-Fos expression in Fluoro-Gold/tyrosine hydroxylase-immunoreactive neurons increased during the afternoon in the A2 of both OVX+E and OVX+EP rats, in the locus coeruleus (LC) of OVX+EP rats, but was unchanged in the A1. The selective lesion of LC terminals, by intracerebroventricular N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine, reduced the surge of LH in OVX+EP but not in OVX+E rats. Thus, estradiol and progesterone activate A2 and LC neurons, respectively, and this is associated with the increased release of NE in the POA and the magnitude of the LH surge. NE stimulates LH secretion, at least in part, through activation of anteroventral periventricular neurons. These findings contribute to elucidation of the role played by NE during the positive feedback of ovarian steroids.

Prolactin (PRL) is tonically inhibited by dopamine (DA) released from neurons in the arcuate and periventricular nuclei. Kisspeptin plays a pivotal role in LH regulation. In rodents, kisspeptin neurons are found mostly in the anteroventral periventricular and arcuate nuclei, but the physiology of arcuate kisspeptin neurons is not completely understood. We investigated the role of kisspeptin in the control of hypothalamic DA and pituitary PRL secretion in adult rats. Intracerebroventricular kisspeptin-10 (Kp-10) elicited PRL release in a dose-dependent manner in estradiol (E2)-treated ovariectomized rats (OVX+E2), whereas no effect was found in oil-treated ovariectomized rats (OVX). Kp-10 increased PRL release in males and proestrous but not diestrous females. Associated with the increase in PRL release, intracerebroventricular Kp-10 reduced Fos-related antigen expression in tyrosine hydroxylase-immunoreactive (ir) neurons of arcuate and periventricular nuclei in OVX+E2 rats, with no effect in OVX rats. Kp-10 also decreased 3,4-dihydroxyphenylacetic acid concentration and 3,4-dihydroxyphenylacetic acid-DA ratio in the median eminence but not striatum in OVX+E2 rats. Double-label immunofluorescence combined with confocal microscopy revealed kisspeptin-ir fibers in close apposition to and in contact with tyrosine hydroxylase-ir perikarya in the arcuate. In addition, Kp-10 was not found to alter PRL release from anterior pituitary cell cultures regardless of E2 treatment. We provide herein evidence that kisspeptin regulates PRL release through inhibition of hypothalamic dopaminergic neurons, and that this mechanism is E2 dependent in females. These findings suggest a new role for central kisspeptin with possible implications for reproductive physiology.