Knockdown of mechanosensitive adaptor Hic-5 ameliorates post-traumatic osteoarthritis in rats through repression of MMP-13

Osteoarthritis (OA) is the most common joint disease associated with articular cartilage destruction. Matrix metalloproteinase-13 (MMP-13) has an essential role in OA pathogenesis by degradation of collagen II, a major component of articular cartilage. Hydrogen peroxide-inducible clone-5 (Hic-5; TGFB1I1), a transforming growth factor-β-inducible mechanosensor, has previously been reported to promote OA pathogenesis by upregulating MMP-13 expression in mouse osteoarthritic lesions. In our current study, immunohistochemical analysis showed that Hic-5 protein expression was increased in human OA cartilage compared with normal cartilage. Functional experiments demonstrated that Hic-5 and MMP-13 expression was increased by mechanical stress, and mechanical stress-induced MMP-13 expression was suppressed by Hic-5 siRNA in human chondrocytes. Moreover, intracellular localization of Hic-5 shifted to the nucleus from focal adhesions in human chondrocytes subjected to mechanical stress, and nuclear Hic-5 increased MMP-13 gene expression. In vivo, intra-articular injection of Hic-5 siRNA decreased the Osteoarthritis Research Society International score and MMP-13 protein expression in articular cartilage of OA rats. Our findings suggest that Hic-5 regulates transcription of MMP-13 in human chondrocytes, and Hic-5 may be a novel therapeutic target for OA because OA progression was suppressed by intra-articular injection of Hic-5 siRNA in rats.

Hypercholesterolemic Dysregulation of Calpain in Lymphatic Endothelial Cells Interferes With Regulatory T-Cell Stability and Trafficking

BACKGROUND

Although hypercholesterolemia reportedly counteracts lymphocyte trafficking across lymphatic vessels, the roles of lymphatic endothelial cells (LECs) in the lymphocyte regulations remain unclear. Previous studies showed that calpain-an intracellular modulatory protease-interferes with leukocyte dynamics in the blood microcirculation and is associated with hypercholesterolemic dysfunction in vascular endothelial cells.

METHODS

This study investigated whether the calpain systems in LECs associate with the LEC-lymphocyte interaction under hypercholesterolemia using gene-targeted mice.

RESULTS

Lipidomic analysis in hypercholesterolemic mice showed that several lysophospholipids, including lysophosphatidic acid, accumulated in the lymphatic environment. Lysophosphatidic acid enables the potentiation of calpain systems in cultured LECs, which limits their ability to stabilize regulatory T cells (Treg) without altering Th1/Th2 (T helper type1/2) subsets. This occurs via the proteolytic degradation of MEKK1 (mitogen-activated protein kinase kinase kinase 1) and the subsequent inhibition of TGF (transforming growth factor)-β1 production in LECs. Targeting calpain systems in LECs expanded Tregs in the blood circulation and reduced aortic atherosclerosis in hypercholesterolemic mice, concomitant with the reduction of proinflammatory macrophages in the lesions. Treg expansion in the blood circulation and atheroprotection in calpain-targeted mice was prevented by the administration of TGF-β type-I receptor inhibitor. Moreover, lysophosphatidic acid-induced calpain overactivation potentiated the IL (interleukin)-18/NF-κB (nuclear factor κB)/VCAM1 (vascular cell adhesion molecule 1) axis in LECs, thereby inhibiting lymphocyte mobility on the cells. Indeed, VCAM1 in LECs was upregulated in hypercholesterolemic mice and human cases of coronary artery disease. Neutralization of VCAM1 or targeting LEC calpain systems recovered afferent Treg transportation via lymphatic vessels in mice.

CONCLUSIONS

Calpain systems in LECs have a key role in controlling Treg stability and trafficking under hypercholesterolemia.

Central administration of neuropeptide Y reduces the cellular heat stress response and may enhance spleen antioxidative functions in heat-exposed chicks

Previously it was found that mRNA expression of neuropeptide Y (NPY) was increased in the chicken brain under heat stress. NPY has also been reported as an anti-stress factor to regulate brain functions in heat-exposed chicks. However, to the best of our knowledge, there is no report on the action of central NPY in the immune organs under heat stress. The aim of this study was to examine whether central injection of NPY can regulate heat stress response in the spleen and liver. After intracerebroventricular (ICV) injection of NPY, chicks were exposed to control thermoneutral temperature (CT: 30 ± 1 °C) or high ambient temperature (HT: 35 ± 1 °C) chambers for 60 min. Central injection of NPY caused lowering in rectal temperature under CT, but not under HT. Moreover, ICV injection of NPY caused a significant lower mRNA expression of heat-shock protein-70 and higher expression of glutathione synthase in the spleen, but not liver. Furthermore, plasma uric acid concentrations were significantly increased by the ICV injection of NPY in chicks under HT. These results indicate that brain NPY may contribute to attenuate the intracellular heat stress response and enhance antioxidative status in the immune organ, spleen in chicks.

Intracerebroventricular injection of taurine induces hypothermia through modifying monoaminergic pathways in chicks

Brain monoamines are reported to regulate body temperature and food intake. The objective of this study was to investigate the mechanism of brain monoamine metabolism in taurine-induced hypothermia and appetite suppression. In Experiment 1, 5-day-old male Julia layer chicks (n = 10) were subjected to intracerebroventricular (ICV) injection with saline or taurine (5 μmol/10 μL). In Experiment 2, the chicks were ICV injected with saline, taurine, fusaric acid (dopamine-β-hydroxylase inhibitor: 558 nmol), or taurine with fusaric acid. In Experiment 3, the chicks were ICV injected with saline, taurine, para-chlorophenylalanine (PCPA, tryptophan hydroxylase inhibitor: 400 nmol), or taurine with PCPA. In Experiment 4, the chicks were ICV injected with saline, taurine, clorgyline (monoamine oxidase inhibitor: 81 nmol), or taurine with clorgyline. Central taurine lowered rectal temperature at 30 min post-injection and increased norepinephrine in the brainstem and its metabolite 3-methoxy-4-hydroxyphenylglycol in both the diencephalon and brainstem. Similarly, taurine treatment induced increases in serotonin (5-HT) and its metabolite 5-hydroxyindoleacetic acid in the diencephalon. Fusaric acid completely and PCPA partially, but not clorgyline, attenuated taurine-induced hypothermia. The anorexigenic effect of taurine was partially attenuated by PCPA, but not fusaric acid nor clorgyline. In conclusion, central taurine activates dopamine-β-hydroxylase and tryptophan hydroxylase to produce norepinephrine and 5-HT, and then induces hypothermia, but 5-HT alone may be linked with taurine-induced anorexia in chicks.

Oral Administration of L-Citrulline Changes Brain Free Amino Acid and Monoamine Metabolism in Heat-Exposed Broiler Chickens

High ambient temperatures (HT) in summer are becoming more severe due to global warming, leading to severe adverse effects on poultry production. Recently, we have reported that oral administration of L-citrulline (L-Cit) can minimize hyperthermia in chickens under HT. However, whether oral L-Cit can enter the brain, the center for thermoregulation, has not been studied. We investigated the effects of oral administration of L-Cit on free amino acids and monoamines in the diencephalon region of the brain of heat-exposed broilers. Broilers were treated with L-Cit (40 mmol/20 ml/bird), then moved to a chamber at HT (30 ± 1°C) or to a thermoneutral temperature (CT: 22 ± 1°C) chamber for 2 h. Control groups were given methyl cellulose solution and placed in the CT or HT chambers. After 2 h of exposure to HT, there were increased brain concentrations of Cit in comparison with concentrations in broilers exposed to CT, whereas brain ornithine (Orn) concentrations were decreased, and arginine (Arg) concentrations were not changed. Interestingly, oral administration of L-Cit increased brain concentration of Cit, Arg, and Orn under both CT and HT. Tryptophan and its metabolite, serotonin (5-HT) concentrations were lower in the brain under HT than under CT. HT did not change brain concentrations of tyrosine, but dopamine (DA, a metabolite of tyrosine) concentrations decreased, and methoxyhydroxyphenylglycol (MHPG, a metabolite of DA) concentrations increased in comparison with CT. Oral administration of L-Cit decreased brain concentrations of both tryptophan and tyrosine under CT and HT without changing 5-HT; however, DA levels declined under HT. Moreover, MHPG concentrations increased. In conclusion, these results suggest that metabolism of amino acids and metabolism of DA can be enhanced in the brain by oral administration of L-Cit. Metabolic changes in the brain in response to oral administration of L-Cit may influence the thermoregulatory center in the brain, leading to a reduction in body temperature and conferring thermotolerance in heat-exposed broiler chickens.

Intracrine activity involving NAD-dependent circadian steroidogenic activity governs age-associated meibomian gland dysfunction

Canonically, hormones are produced in the endocrine organs and delivered to target tissues. However, for steroids, the concept of tissue intracrinology, whereby hormones are produced in the tissues where they exert their effect without release into circulation, has been proposed, but its role in physiology/disease remains unclear. The meibomian glands in the eyelids produce oil to prevent tear evaporation, which reduces with aging. Here, we demonstrate that (re)activation of local intracrine activity through nicotinamide adenine dinucleotide (NAD⁺)-dependent circadian 3β-hydroxyl-steroid dehydrogenase (3β-HSD) activity ameliorates age-associated meibomian gland dysfunction and accompanying evaporative dry eye disease. Genetic ablation of 3β-HSD nullified local steroidogenesis and led to atrophy of the meibomian gland. Conversely, reactivation of 3β-HSD activity by boosting its coenzyme NAD⁺ availability improved glandular cell proliferation and alleviated the dry eye disease phenotype. Both women and men express 3β-HSD in the meibomian gland. Enhancing local steroidogenesis may help combat age-associated meibomian gland dysfunction.

Central Taurine Attenuates Hyperthermia and Isolation Stress Behaviors Augmented by Corticotropin-Releasing Factor with Modifying Brain Amino Acid Metabolism in Neonatal Chicks

The objective of this study was to determine the effects of centrally administered taurine on rectal temperature, behavioral responses and brain amino acid metabolism under isolation stress and the presence of co-injected corticotropin-releasing factor (CRF). Neonatal chicks were centrally injected with saline, 2.1 pmol of CRF, 2.5 μmol of taurine or both taurine and CRF. The results showed that CRF-induced hyperthermia was attenuated by co-injection with taurine. Taurine, alone or with CRF, significantly decreased the number of distress vocalizations and the time spent in active wakefulness, as well as increased the time spent in the sleeping posture, compared with the saline- and CRF-injected chicks. An amino acid chromatographic analysis revealed that diencephalic leucine, isoleucine, tyrosine, glutamate, asparagine, alanine, β-alanine, cystathionine and 3-methylhistidine were decreased in response to taurine alone or in combination with CRF. Central taurine, alone and when co-administered with CRF, decreased isoleucine, phenylalanine, tyrosine and cysteine, but increased glycine concentrations in the brainstem, compared with saline and CRF groups. The results collectively indicate that central taurine attenuated CRF-induced hyperthermia and stress behaviors in neonatal chicks, and the mechanism likely involves the repartitioning of amino acids to different metabolic pathways. In particular, brain leucine, isoleucine, cysteine, glutamate and glycine may be mobilized to cope with acute stressors.

Adult-onset hypothyroidism causes mechanical hypersensitivity due to peripheral nerve hyperexcitability based on voltage-gated potassium channel downregulation in male mice

Thyroid hormones play an important role in the central and peripheral nervous system functions. Approximately 50% of adult-onset hypothyroid patients have sensory symptoms including pain, possibly caused by peripheral neuropathy. However, the mechanism causing the pain has not been clarified. We generated an adult-onset hypothyroid model animal by administering 50 ppm propylthiouracil (PTU) for 5 weeks to male mice. Female mice were not tested in this study. Mechanical hypersensitivity, determined by the von Frey hair test, was observed during the PTU exposure and recovered after the exposure termination. The sciatic nerve compound action potential was also analyzed. Under single-pulse stimulation, no significant change in the threshold and conduction velocity was observed in the PTU-administered group. On the other hand, under train-pulse stimulation, the latency delay in the Aδ-fiber component was less in the PTU-administered group in Week 4 of PTU exposure, indicating relative hyperexcitability. Fluticasone, which is the anti-inflammatory agent with an ability to activate the voltage-gated potassium channel subfamily A (Kv1), restored the decrease in the latency change ratio by PTU exposure under the train-pulse stimulation supporting our hypothesis that Kv1 may be involved in the conductivity change. Kv1.1 protein level decreased significantly in the sciatic nerve of the PTU-administered group. These results indicate that adult-onset hypothyroidism causes mechanical hypersensitivity owing to hyperexcitability of the peripheral nerve and that reduction of Kv1.1 level may be involved in such alteration.

Liver metabolomic analysis in broiler chicks: Profiling the metabolites after oral administration of l-citrulline

Hypothermia is directly linked to metabolism; however, it is still unknown how the overall metabolism is altered by oral administration of hypothermic agent, l-citrulline (l-Cit). The present study aimed to determine the characteristics of liver metabolites of chicks orally administered l-Cit to provide a greater understanding of its metabolism. Capillary electrophoresis-time-of-flight mass spectrometry (CE-TOFMS) and liquid chromatography-time-of-flight mass spectrometry (LC-TOFMS) were conducted on liver samples after oral administration of l-Cit. A total of 361 liver metabolites were identified. Although a small number of samples were used for each group, a principal component analysis and heatmap patterns confirmed that the composition of metabolites could be segregated from each other. Of the 361 compounds detected in the liver, 41 compounds, including amino acids related to the Cit-arginine (Arg) cycle, argininosuccinic acid, Arg, ornithine, and Cit, as well as gamma aminobutyric acid, glycine, histidine, and nicotinamide adenine dinucleotide were abundant in l-Cit-treated livers. In contrast, 24 compounds containing fatty acids, amino acids, and cyclic adenosine monophosphate were lower in the l-Cit group. These data imply that the active Cit-Arg cycle, TCA cycle metabolism, and a low activity in fatty acid metabolism occur in l-Cit-treated broiler chicks.

Oral administration of L-citrulline changes the concentrations of plasma hormones and biochemical profile in heat-exposed broilers

We examined the effects of oral administration of L-citrulline (L-Cit) on plasma metabolic hormones and biochemical profile in broilers. Food intake, water intake, and body temperature were also analyzed. After dual oral administration (20 mmol/head/administration) of L-Cit, broilers were exposed to a high ambient temperature (HT; 30 ± 1°C) chamber for 120 min. Oral administration of L-Cit reduced (p < .001) rectal temperature in broilers. Food intake was increased (p < .05) by heat stress, but it was reduced (p < .05) by L-Cit. Plasma levels of 3,5,3'-triiodothyronine, which initially increased (p < .0001) due to heat stress, were reduced (p < .01) by oral administration of L-Cit. Plasma insulin levels were increased by heat exposure (p < .01) and oral L-Cit (p < .05). Heat stress caused a decline (p < .05) in plasma thyroxine. Plasma lactic acid (p < .05) and non-esterified fatty acids (p < .01) were increased in L-Cit-treated heat-exposed broilers. In conclusion, our results suggest that oral L-Cit can modulate plasma concentrations of major metabolic hormones and reduces food intake in broilers.

Central GABAA receptor mediates taurine-induced hypothermia and possibly reduces food intake in thermo-neutral chicks and regulates plasma metabolites in heat-exposed chicks

The aim of this study was to examine the central action of taurine on body temperature and food intake in neonatal chicks under control thermoneutral temperature (CT) and high ambient temperature (HT). Intracerebroventricular injection of taurine caused dose-dependent hypothermia and reduced food intake under CT. The mRNA expression of the GABA_A receptors, GABA_AR-α1 and GABA_AR-γ, but not that of GABA_BR, significantly decreased in the diencephalon after central injection of taurine. Subsequently, we found that picrotoxin, a GABA_AR antagonist, attenuated taurine-induced hypothermia. Central taurine significantly decreased the brain concentrations of 3-methoxy-4-hydroxyphenylglycol, a major metabolite of norepinephrine; however, the concentrations of serotonin, dopamine, and the epinephrine metabolites, 3,4-hydroxyindoleacetic acid and homovanillic acid, were unchanged. Although hypothermia was not observed under HT after central injection of taurine, plasma glucose and uric acid levels were higher, and plasma sodium and calcium levels were lower, than those in chicks under CT. In conclusion, brain taurine may play a role in regulating body temperature and food intake in chicks through GABA_AR. The changes in plasma metabolites under heat stress suggest that brain taurine may play an important role in maintaining homeostasis in chicks.

Potential Role of Amino Acids in the Adaptation of Chicks and Market-Age Broilers to Heat Stress

Increased average air temperatures and more frequent and prolonged periods of high ambient temperature (HT) associated with global warming will increasingly affect worldwide poultry production. It is thus important to understand how HT impacts poultry physiology and to identify novel approaches to facilitate improved adaptation and thereby maximize poultry growth, health and welfare. Amino acids play a role in many physiological functions, including stress responses, and their relative demand and metabolism are altered tissue-specifically during exposure to HT. For instance, HT decreases plasma citrulline (Cit) in chicks and leucine (Leu) in the embryonic brain and liver. The physiological significance of these changes in amino acids may involve protection of the body from heat stress. Thus, numerous studies have focused on evaluating the effects of dietary administration of amino acids. It was found that oral l-Cit lowered body temperature and increased thermotolerance in layer chicks. When l-Leu was injected into fertile broiler eggs to examine the cause of reduction of Leu in embryos exposed to HT, in ovo feeding of l-Leu improved thermotolerance in broiler chicks. In ovo injection of l-Leu was also found to inhibit weight loss in market-age broilers exposed to chronic HT, giving rise to the possibility of developing a novel biotechnology aimed at minimizing the economic losses to poultry producers during summer heat stress. These findings and the significance of amino acid metabolism in chicks and market-age broilers under HT are summarized and discussed in this review.

SAT-442 The Impact of Chronic Excess Iodine Intake in Adult Mice Behavior

Iodine is one of the essential micronutrient which is required for the synthesis of thyroid hormones. Thus, iodine deficiency may result in the hypothyroidism. Iodine deficiency is one of the most common causes of preventable mental retardation and brain damage in the world. On the other hand, Japanese iodine intake exceeds that of most other countries, due to the significant seaweed consumption such as kelp. The Japanese Ministry of Health, Labour and Welfare estimates average iodine consumption at 1.2mg/day in Japan. In contrast, the recommended tolerable upper intake levels for adult is 1.1 mg / day in the United States. Generally, Japanese takes twenty times higher amount of iodine than Americans. Iodine tolerance among individual humans varies greatly, and the excess iodine can cause both hyper- and hypo- thyroidism. Furthermore, the effect of thyroid dysfunction due to iodine excess on brain function has not been clarified. In this study, we generated a mouse models for chronic iodine excess and evaluated its effect on brain development. C57BL/6 dams and their pups mice were treated with KIO₃ 37.4mg/l through drinking water. Behavioral experiments (novel object recognition test, novel object in location test, visual discrimination test, and three-room social behavior test) were conducted at 10-weeks-old. After the behavioral analysis, mice were sacrificed to collect trunk blood and tissues. Excess iodine intake caused hypertrophy of thyroid follicles regardless of the administered dose. However, there were no differences in thyroid hormone status among groups. Thyroid hormone responsive genes in the hippocampus were also not affected in experiment group. In the behavioral analysis, female mice showed an increase in learning ability. In summary, although the chronic overdose of iodine does not affect thyroid hormone levels, it may affect cognitive learning function. The gender difference in the consequence was also observed. These results indicate that the chronic iodine excess may cause various changes, although the body is tolerable with excess iodine.

Neuroprotective actions of cerebellar and pineal allopregnanolone on Purkinje cells

The brain produces steroids de novo from cholesterol, so‐called “neurosteroids.” The Purkinje cell, a cerebellar neuron, was discovered as a major site of the biosynthesis of neurosteroids including sex steroids, such as progesterone, from cholesterol in the brain. Allopregnanolone, a progesterone metabolite, is also synthesized in the cerebellum and acts on the Purkinje cell to prevent cell death of this neuron. Recently, the pineal gland was discovered as an important site of the biosynthesis of neurosteroids. Allopregnanolone, a major pineal neurosteroid, acts on the Purkinje cell for the survival of this neuron by suppressing the expression of caspase‐3, a crucial mediator of apoptosis. This review summarizes the discovery of cerebellar and pineal allopregnanolone and its neuroprotective action on Purkinje cells.

Pineal Neurosteroids: Biosynthesis and Physiological Functions

Similar to the adrenal glands, gonads, and placenta, vertebrate brains also produce various steroids, which are known as "neurosteroids." Neurosteroids are mainly synthesized in the hippocampus, hypothalamus, and cerebellum; however, it has recently been discovered that in birds, the pineal gland, a photosensitive region in the brain, produces more neurosteroids than other brain regions. A series of experiments using molecular and biochemical techniques have found that the pineal gland produces various neurosteroids, including sex steroids, de novo from cholesterol. For instance, allopregnanolone and 7α-hydroxypregnenolone are actively produced in the pineal gland, unlike in other brain regions. Pineal 7α-hydroxypregnenolone, an up-regulator of locomotion, enhances locomotor activity in response to light stimuli in birds. Additionally, pineal allopregnanolone acts on Purkinje cells in the cerebellum and prevents neuronal apoptosis within the developing cerebellum in juvenile birds. Furthermore, exposure to light during nighttime hours can cause loss of diurnal variations of pineal allopregnanolone synthesis during early posthatch life, eventually leading to cerebellar Purkinje cell death in juvenile birds. In light of these new findings, this review summarizes the biosynthesis and physiological functions of pineal neurosteroids. Given that the circadian rhythms of individuals in modern societies are constantly interrupted by artificial light exposure, these findings in birds, which are excellent model diurnal animals, may have direct implications for addressing problems regarding the mental health and brain development of humans.

Alleviation of murine osteoarthritis by deletion of the focal adhesion mechanosensitive adapter, Hic-5

Excessive mechanical stress is a major cause of knee osteoarthritis. However, the mechanism by which the mechanical stress begets osteoarthritis development remains elusive. Hydrogen peroxide-inducible clone-5 (Hic-5; TGFβ1i1), a TGF-β inducible focal adhesion adaptor, has previously been reported as a mediator of mechanotransduction. In this study, we analyzed the in vivo function of Hic-5 in development of osteoarthritis, and found that mice lacking Hic-5 showed a significant reduction in development of osteoarthritis in the knee. Furthermore, we found reduced expression of catabolic genes, such as metalloproteinase-13 and a disintegrin and metalloproteinase with thrombospondin type 1 motif 5 in osteoarthritic lesions in mice lacking Hic-5. During osteoarthritis development, Hic-5 is detected in chondrocytes of articular cartilage. To investigate the role of Hic-5 in chondrocytes, we isolated chondrocytes from articular cartilage of wild type and Hic-5-deficient mice. In these primary cultured chondrocytes, Hic-5 deficiency resulted in suppression of catabolic gene expression induced by osteoarthritis-related cytokines such as tumor necrosis factor α and interleukin 1β. Furthermore, Hic-5 deficiency in chondrocytes suppressed catabolic gene expression induced by mechanical stress. Revealing the regulation of chondrocyte catabolism by Hic-5 contributes to understanding the pathophysiology of osteoarthritis induced by mechanical stress.

Light-at-night exposure affects brain development through pineal allopregnanolone-dependent mechanisms

The molecular mechanisms by which environmental light conditions affect cerebellar development are incompletely understood. We showed that circadian disruption by light-at-night induced Purkinje cell death through pineal allopregnanolone (ALLO) activity during early life in chicks. Light-at-night caused the loss of diurnal variation of pineal ALLO synthesis during early life and led to cerebellar Purkinje cell death, which was suppressed by a daily injection of ALLO. The loss of diurnal variation of pineal ALLO synthesis induced not only reduction in pituitary adenylate cyclase-activating polypeptide (PACAP), a neuroprotective hormone, but also transcriptional repression of the cerebellar Adcyap1 gene that produces PACAP, with subsequent Purkinje cell death. Taken together, pineal ALLO mediated the effect of light on early cerebellar development in chicks.

L-Leucine increases the daily body temperature and affords thermotolerance in broiler chicks

OBJECTIVE

Heat stress poses an increasing threat for poultry production. Some amino acids have been found to play critical roles in affording thermotolerance. Recently, it was found that in ovo administration of L-leucine (L-Leu) altered amino acid metabolism and afforded thermotolerance in heat-exposed broiler chicks.

METHODS

In this study, two doses (35 and 70 μmol/egg) of L-Leu were administered in ovo on embryonic day 7 to determine their effect on rectal temperature (RT), body weight (BW) and thyroid hormones at hatching. Changes in RT, BW, and thermotolerance in post-hatched chicks were also analyzed.

RESULTS

It was found that in ovo administration of L-Leu dose-dependently reduced RT and plasma thyroxine (T4) level just after hatching. In post-hatched neonatal broiler chicks, however, the higher dose of L-Leu administered in ovo significantly increased RT without affecting BW gain. In chicks that had been exposed to heat stress, the RT was significantly lowered by in ovo administration of L-Leu (high dose) in comparison with the control chicks under the same high ambient temperature (HT: 35°C±1°C, 120 min).

CONCLUSION

In ovo administration of L-Leu in a high dose contributed to an increased daily body temperature and afforded thermotolerance under HT in neonatal broiler chicks.

183 Generation of porcine embryonic stem cell lines derived from nuclear transfer embryos reconstructed with induced pluripotent stem cells

To establish a porcine embryonic stem (ES) cell line that not only maintains self-renewing capacity but also exhibits pluripotency [Haraguchi et al. 2012 J. Reprod. Dev. 58, 707-716], 6 synthetic porcine RNAs (Oct4, Sox2, Klf4, c-Myc, Nanog, and Lin28) were chemically transfected into outgrowth cultured cells derived from the inner cell mass of in vitro-produced porcine embryos. Subsequently, cells grew as compact, dome-shaped colonies displaying alkaline phosphatase activity and were cultured for more than 20 passages. Although 13 candidate cell lines were generated (13/43, 30%), none formed teratomas after injection of the cells into SCID (sever combined immunodeficiency) mice. We also observed that when transfection of the exogeneous RNAs was discontinued, the cells no longer maintained a stem cell morphology and began to differentiate (13/13, 100%). This suggests that continuous expression of exogenous reprogramming factors is necessary to maintain induced pluripotency in the pig. Next, we used cloned embryos reconstructed with porcine induced pluripotent stem cells (piPSC), which were created using a recombinant lentivirus expression vector carrying 6 mouse reprogramming factor genes (the same as above) and green fluorescent protein (GFP) (Fukuda et al. 2017 J. Cell Biochem. 118, 537-553]. The piPSC were dispersed to a single cell suspension and electrically fused to cytoplasts prepared following enucleation of in vitro-matured zona-free metaphase II-arrested oocytes. A second cytoplast was then fused to the first reconstruct (double cytoplast nuclear transfer). Reconstructs were electrically activated and cultured in microwells with porcine zygote medium-3 (PZM3). After 5 days, reconstructed embryos developed to GFP-positive blastocysts (10/93, 11%) and 4- to 8-cell stages (25/93, 27%). The blastocysts (10) and 4- to 8-cell-stage embryos (25) were transferred onto mouse embryonic fibroblast feeder cells for outgrowth culture in FCS-based ES cell medium supplemented with 2% polyvinylpyrrolidone. After 24h, the medium was changed to piPSC medium containing CHIR99021, PD0325901, thiazovivin, and GF-109203x. Embryos attached to the feeder cells began to outgrow (8/10 of blastocysts and 6/25 of 4- to 8-cell-stage embryos). To date, 3 ES-like cell lines have been established from blastomeres of embryos (3/25, 12%) but not from blastocysts (0/10, 0%). They show GFP fluorescence and have been maintained continuously in culture for more than 20 passages without any overt changes in morphology. These results suggest that the constant expression of reprogramming factors and the use of combinations of specific small molecule inhibitors largely contribute to the establishment of pluripotent cells in the pig. Further characterisation of the cells is ongoing, including methylation status of the X chromosome and the capacity for in vivo differentiation.

Endothelial calpain systems orchestrate myofibroblast differentiation during wound healing

The transformation of fibroblasts to myofibroblasts plays a major role in fibrogenic responses during dermal wound healing. We show a contribution of calpain systems (intracellular regulatory protease systems) in vascular endothelial cells (ECs) to myofibroblast differentiation in wound sites. Dermal wound healing experiments in mice found that calpastatin (an endogenous inhibitor of calpains) is enriched in preexisting vessels but not in newly formed capillaries. Transgenic overexpression of calpastatin in ECs delayed wound healing in mice as well as reducing the keratinocyte layer, extracellular matrix deposition, and myofibroblast accumulation in wound sites. EC and leukocyte markers, however, remain unchanged. Calpastatin overexpression reduced the expression of genes encoding platelet-derived growth factor-B and PDGF receptor-β (PDGFR-β). Topical application of platelet-derived growth factor-BB-containing ointment to wounds accelerated healing in control mice, but calpastatin overexpression prevented this acceleration. In cultured human dermal fibroblasts, α-smooth muscle actin and PDGFR-β were up-regulated by coculturing with ECs, but this action was inhibited by suppression of EC calpain activity. EC-driven transformation of mouse dermal fibroblasts was also suppressed by calpastatin overexpression in ECs. These results suggest that endothelial calpain systems influence PDGFR-β signaling in fibroblasts, EC-driven myofibroblast differentiation, and subsequent fibrogenic responses in wounds.-Miyazaki, T., Haraguchi, S., Kim-Kaneyama, J.-R., Miyazaki, A. Endothelial calpain systems orchestrate myofibroblast differentiation during wound healing.

7α-Hydroxypregnenolone regulating locomotor behavior identified in the brain and pineal gland across vertebrates

The brain synthesizes steroids de novo from cholesterol, which are called neurosteroids. Based on extensive studies on neurosteroids over the past thirty years, it is now accepted that neurosteroidogenesis in the brain is a conserved property across vertebrates. However, the formation of bioactive neurosteroids in the brain is still incompletely elucidated in vertebrates. In fact, we recently identified 7α-hydroxypregnenolone (7α-OH PREG) as a novel bioactive neurosteroid stimulating locomotor behavior in the brain of several vertebrates. The follow-up studies have demonstrated that the stimulatory action of brain 7α-OH PREG on locomotor behavior is mediated by the dopaminergic system across vertebrates. More recently, we have further demonstrated that the pineal gland, an endocrine organ located close to the brain, is a major site of the formation of bioactive neurosteroids. In addition to the brain, the pineal gland actively produces 7α-OH PREG de novo from cholesterol as a major pineal neurosteroid that acts on the brain to control locomotor rhythms. This review summarizes the identification, biosynthesis and mode of action of brain and pineal 7α-OH PREG, a new bioactive neurosteroid regulating locomotor behavior, across vertebrates.

7α-Hydroxypregnenolone regulates diurnal changes in sexual behavior of male quail

In the Japanese quail, 7α-hydroxypregnenolone, a previously undescribed avian neurosteroid, is actively produced in the brain. 7α-Hydroxypregnenolone acts as a novel neuronal activator to stimulate locomotor activity of quail. Therefore, in this study, we determined whether 7α-hydroxypregnenolone changes the expression of sexual behavior in Japanese quail. We first measured diurnal changes in sexual behavior of male quail exposed to a long-day photoperiod. We found that sexual behavior of male quail was high in the morning when endogenous 7α-hydroxypregnenolone level is high. Subsequently, we centrally administered 7α-hydroxypregnenolone in the evening when endogenous 7α-hydroxypregnenolone level is low. In the 30 min after intracerebroventricular (ICV) injection, 7α-hydroxypregnenolone dose dependently increased the frequency of sexual behavior of male quail. However, 7β-hydroxypregnenolone, a stereoisomer of 7α-hydroxypregnenolone, did not effect on the frequency of sexual behavior of male quail. In addition, to confirm the action of 7α-hydroxypregnenolone on sexual behavior, male birds received an ICV injection of ketoconazole, an inhibitor of cytochrome P450s, and behavioral experiments were performed in the morning. Ketoconazole significantly decreased the frequency of sexual behavior of male quail, whereas administration of 7α-hydroxypregnenolone to ketoconazole-treated males increased the frequency of their sexual behavior. These results indicate that 7α-hydroxypregnenolone regulates diurnal changes in sexual behavior of male quail.

Nucleotide sequence and expression of relaxin-like gonad-stimulating peptide gene in starfish Asterina pectinifera

Starfish gonad-stimulating substance (GSS) is the only known invertebrate peptide hormone responsible for final gamete maturation, rendering it functionally analogous to gonadotropins in vertebrates. Because GSS belongs to the relaxin-like peptide family, we propose renaming for starfish gonadotropic hormone as relaxin-like gonad-stimulating peptide (RGP). This study examined the primary structure and expression regulation of the RGP gene in starfish Asterina pectinifera. RGP consisted of 3896 base pairs (bp) divided over two exons, exon 1 of 208 bp and exon 2 of 2277 bp, and one intron of 1411 bp. Promoter sequences, CAAT and TATA boxes, were present in the 5'-upstream region of the coding DNA sequence of RGP. The transcript was 2485 bases (b) in length. The AAUAAA polyadenylation signal was found in 3'-untranslated region over 2kb away from the stop codon. This showed that only 14% of the RGP mRNA was translated into the peptide, because a size of the open-reading frame was 351 b. Furthermore, an analysis by using real-time quantitative PCR with specific primers for RGP showed that mRNA of RGP was expressed at high levels in the radial nerves. Expression was also observed in the cardiac stomachs, although the level was low, and trace levels were detected in the gonads, pyloric caeca and tube feet. This result suggests that the RGP gene is transcribed mainly in the radial nerves of A. pectinifera.

46 VITRIFICATION AT THE GERMINAL VESICLE STAGE TRIGGERS PRECOCIOUS MEIOTIC RESUMPTION BUT DOES NOT AFFECT CYTOPLASMIC MATURATION IN CUMULUS-ENCLOSED PORCINE OOCYTES DURING IN VITRO MATURATION

Previously we have reported a vitrification protocol that allows preservation of immature porcine oocytes in large numbers (Somfai et al. 2014 PLoS One 9, e97731). However, despite high survival rates, embryo development rates have remained low. The aim of our current research is to reveal factors potentially responsible for reduced developmental competence of vitrified oocytes. As a first step, we investigated the effects of vitrification at the germinal vesicle stage on subsequent nuclear progression and the normality of cytoplasmic functions during in vitro maturation (IVM). Cumulus-enclosed porcine oocytes were vitrified in microdrops, stored, and then warmed by our method (Somfai et al. 2015 Reprod. Fertil. Dev. 27, 124). Then the oocytes were subjected to IVM for 46 h in a chemically defined porcine oocyte medium. During the first 22 h of IVM, the medium was supplemented with 1 mM dibutyryl cyclic adenosine monophosphate, 10 IU mL–1 of eCG, and 10 IU mL–1 of hCG. The following 24 h of IVM was performed in porcine oocyte medium without any supplementation. We compared vitrified/warmed oocytes (vitrified group) with freshly collected immature oocytes (control group) in terms of (1) nuclear progression, (2) intracellular glutathione (GSH), and (3) adenosine triphosphate levels throughout IVM. Each experiment was replicated at least 3 times. Results were analysed by one-way ANOVA and Tukey’s multiple comparison test. A total of 510 oocytes were vitrified of which 422 (82.3%) survived. Only live oocytes were subjected to subsequent assays. Orcein staining revealed that after 22 h of IVM, a significantly higher percentage (P < 0.05) of vitrified oocytes showed germinal vesicle breakdown compared with the control group (22.0 v. 0.9%, respectively). In a similar fashion, after 30 h IVM, a significantly higher (P < 0.05) percentage of oocytes reached the metaphase-II (MII) stage in the vitrified group than in the control group (21.8 v. 0%, respectively). After 46 h of IVM, there was no difference between the vitrified and control groups in terms of the percentage of MII stage oocytes (93.9 and 86.3%, respectively). Analysis of GSH levels in oocytes by the 5,5′-dithio-bis-2-nitrobenzoic acid-glutathione disulfide reductase recycling assay showed no significant difference between the vitrified and control groups at 0 h (6.7 and 7.0 pmol, respectively), 22 h (5.5 and 5.5 pmol, respectively), and 46 h (6.9 and 7.9 pmol, respectively) of IVM. Adenosine triphosphate assay (FL-ASC; Sigma-Aldrich Co., St. Louis, MO) revealed similar adenosine triphosphate contents in the oocytes of the vitrified and control groups at 0 h (1.53 and 1.61 pmol, respectively), 22 h (1.67 and 1.70 pmol, respectively), and 46 h (1.65 and 1.83 pmol, respectively) of IVM. In conclusion, vitrification triggered precocious nuclear maturation even in the presence of dibutyryl cyclic adenosine monophosphate; however, it did not affect GSH levels and overall metabolism. This work was supported by JSPS KAKENHI (Grant Number: 26870839) and JST/JICA SATREPS.

Possible hormonal interaction for eliciting courtship behavior in the male newt, Cynops pyrrhogaster

Reproductive behavior in amphibians, as in other vertebrate animals, is under the control of multiple hormonal substances. Prolactin (PRL), arginine vasotocin (AVT), androgen, and 7α-hydroxypregnenolone (7α-OH PREG), four such substances with hormonal activity, are known to be involved in the expression of the tail vibration behavior which is the initial step of courtship performed by the male newt, Cynops pyrrhogaster. As current information on the interaction(s) between these hormones in terms of eliciting tail vibration behavior is limited, we have investigated whether the decline of expression of tail vibration behavior due to suppression of the activity of any one of these hormones can be restored by supplying any one of the other three hormones exogenously. Expression of the behavior was determined in terms of incidence (% of test animals exhibiting the behavior) and frequency (number of times that the behavior was repeated during the test period). Neither PRL nor androgen restored the decline in the incidence and frequency of the tail vibration behavior caused by the suppression of the activity of any one of other three hormones. AVT completely restored both the anti-PRL antibody-induced and flutamide (an androgen receptor antagonist)-induced, but not ketoconazole (an inhibitor of the steroidogenic CYP enzymes)-induced decline in the incidence and frequency of the tail vibration behavior. The neurosteroid, 7α-OH PREG, failed to restore flutamide-induced decline in the incidence and frequency of the behavior. However, it was able to restore both anti-PRL antibody-induced and AVT receptor antagonist-induced decline in the incidence, but not in the frequency of the behavior. In another experiment designed to see the activity of hormones enhancing the frequency of the tail vibration behavior, AVT was revealed to be more potent than 7α-OH PREG. The role of each hormonal substance in determining the expression of the tail vibration behavior was discussed based on the results.

A new relaxin-like gonad-stimulating peptide identified in the starfish Asterias amurensis

Relaxin-like gonad-stimulating peptide (RGP) of starfish Asterina pectinifera was the first invertebrate gonadotropin to have its chemical structure identified. However, it is unclear whether gonadotropic hormones in other species starfish are relaxin-like peptides. Thus, this study tried to identify the molecular structure of gonadotropic hormone in Asterias amurensis. As a result, we identified A. amurensis gonadotropic hormone as the RGP (AamRGP). The DNA sequence encoding AamRGP consisted of 330 base pairs with an open reading frame encoding a peptide of 109 amino acids (aa), including a signal peptide (26 aa), B-chain (20 aa), C-peptide (38 aa) and A-chain (25 aa). Comparing with A. pectinifera RGP (ApeRGP), the amino acid identity levels between AmaRGP and ApeRGP were 58% for the A-chain and 73% for the B-chain. Furthermore, chemical synthetic AamRGP induced gamete spawning and oocyte maturation in ovarian fragments of A. amurensis. In contrast, the ovary of A. pectinifera failed to respond to the AamRGP. This suggested that AamRGP is a new relaxin-like peptide.

7α-Hydroxypregnenolone, a key neuronal modulator of locomotion, stimulates upstream migration by means of the dopaminergic system in salmon

Salmon migrate upstream against an opposing current in their natal river. However, the molecular mechanisms that stimulate upstream migratory behavior are poorly understood. Here, we show that 7α-hydroxypregnenolone (7α-OH PREG), a newly identified neuronal modulator of locomotion, acts as a key factor for upstream migration in salmon. We first identified 7α-OH PREG and cytochrome P450 7α-hydroxylase (P450_7α), a steroidogenic enzyme producing 7α-OH PREG, in the salmon brain and then found that 7α-OH PREG synthesis in the brain increases during upstream migration. Subsequently, we demonstrated that 7α-OH PREG increases upstream migratory behavior of salmon. We further found that 7α-OH PREG acts on dopamine neurons in the magnocellular preoptic nucleus during upstream migration. Thus, 7α-OH PREG stimulates upstream migratory behavior through the dopaminergic system in salmon. These findings provide new insights into the molecular mechanisms of fish upstream migration.

62 COMPARISON OF SUGARS, COMBINATIONS OF PERMEABLE CRYOPROTECTANTS, AND EQUILIBRATION REGIMENS FOR THE SOLID SURFACE VITRIFICATION OF IMMATURE PORCINE OOCYTES

Cryotop and solid surface vitrification are frequently used methods for the cryopreservation of porcine oocytes. These methods differ not only in the vitrification carrier but also in the cryoprotectant (CPA) treatment including the type of sugar, permeable CPA (pCPA) combinations, and the equilibration regimen. This study compared the distinct points of CPA treatment of these 2 methods to determine the optimum CPA treatment for the solid surface vitrification of immature porcine oocytes. We vitrified and warmed follicular cumulus-oocyte complexes by our method (Somfai et al. 2014 PLoS One 9, e97731). In each experiment, the vitrification solution consisted of 50 mg mL–1 polyvinyl pyrrolidone, 0.3 M of the actual sugar, and 35% [v/v] in total of the actual pCPA combination (depending on the experiment). After warming, the cumulus-oocyte complexes were subjected to in vitro maturation, IVF, and embryo culture (Kikuchi et al. 2002 Biol. Reprod. 66, 1033–1041). Oocyte survival was assessed after IVF by morphological evaluation, and live oocytes were subjected to in vitro embryo culture. Cleavage and blastocyst rates were calculated from cultured oocytes on Day 2 (Day 0 = IVF) and Day 6, respectively. Each experiment was replicated at least 3 times. Results were analysed by ANOVA. In Experiment 1, we compared trehalose (n = 416) and sucrose (n = 440) as supplementations during vitrification and warming (0.3 M and 0.4 M of each, respectively). There was no significant difference between oocytes vitrified with trehalose or sucrose in terms of survival, cleavage, and blastocyst development (83.2% v. 80.3%, 39.7% v. 42.4%, and 3.6% v. 5.9%, respectively). Thus, vitrification and warming media were supplemented with sucrose thereafter. In Experiment 2, we compared 1 : 1 combinations of ethylene glycol with propylene glycol (EG+PG group, n = 452) and ethylene glycol with dimethyl sulfoxide (EG+DMSO group, n = 465) used as pCPA for equilibration (4% [v/v] pCPA in total for 15 min) and vitrification (35% [v/v] pCPA in total for 30 s). Oocyte survival rate was higher (P < 0.05) in the EG+PG group compared with the EG+DMSO group (73.8% v. 51.1%, respectively); however, cleavage and blastocyst development rates of surviving oocytes were not significantly different between the 2 groups (30.5% v. 44.5% and 4.1% v. 6.3%, respectively). In Experiment 3, we compared an equilibration treatment in 4% [v/v] of EG+PG for 13 to 15 min (regimen A, n = 368) with an equilibration in 15% [v/v] of EG+PG for 5 to 7 min (regimen B, n = 363) for oocyte vitrification. Survival, cleavage, and blastocyst development rates were higher (P < 0.01) for oocytes vitrified using regimen A compared with those vitrified using regimen B (82.5% v. 22.7%, 24.0% v. 7.7%, and 3.2% v. 0%, respectively). In conclusion, trehalose and sucrose are equally effective during vitrification and warming, the combination of EG+PG as pCPA is superior to EG+DMSO, and equilibration in 4% pCPA for 13 to 15 min is superior to that in 15% pCPA for 5 to 7 min for the vitrification of immature porcine oocytes.This work was partly supported by JSPS KAKENHI Grant Number 26870839.

Breakthrough in neuroendocrinology by discovering novel neuropeptides and neurosteroids: 2. Discovery of neurosteroids and pineal neurosteroids

Bargmann-Scharrer's discovery of "neurosecretion" in the first half of the 20th century has since matured into the scientific discipline of neuroendocrinology. Identification of novel neurohormones, such as neuropeptides and neurosteroids, is essential for the progress of neuroendocrinology. Our studies over the past two decades have significantly broadened the horizons of this field of research by identifying novel neuropeptides and neurosteroids in vertebrates that have opened new lines of scientific investigation in neuroendocrinology. We have established de novo synthesis and functions of neurosteroids in the brain of various vertebrates. Recently, we discovered 7α-hydroxypregnenolone (7α-OH PREG), a novel bioactive neurosteroid that acts as a key regulator for inducing locomotor behavior by means of the dopaminergic system. We further discovered that the pineal gland, an endocrine organ located close to the brain, is an important site of production of neurosteroids de novo from cholesterol (CHOL). The pineal gland secretes 7α-OH PREG and 3α,5α-tetrahydroprogesterone (3α,5α-THP; allopregnanolone) that are involved in locomotor rhythms and neuronal survival, respectively. Subsequently, we have demonstrated their mode of action and functional significance. This review summarizes the discovery of these novel neurosteroids and its contribution to the progress of neuroendocrinology.

Involvement of Gαs-proteins in the action of relaxin-like gonad-stimulating substance on starfish ovarian follicle cells

Gonad-stimulating substance (GSS) in starfish is the only known invertebrate peptide hormone responsible for final gamete maturation, rendering it functionally analogous to gonadotropins in vertebrates. In breeding season (stage V), GSS stimulates oocyte maturation to induce 1-methyladenine (1-MeAde) by ovarian follicle cells. The hormonal action of GSS is mediated through the activation of its receptor, G-proteins and adenylyl cyclase. It has been reported that GSS fails to induce 1-MeAde and cyclic AMP (cAMP) production in follicle cells of ovaries during oogenesis (stage IV). This study examined the regulatory mechanism how ovarian follicle cells acquire the potential to respond to GSS by producing 1-MeAde and cAMP. Because the failure of GSS action was due to G-proteins of follicle cells, the molecular structures of Gαs, Gαi, Gαq and Gβ were identified in follicle cells of starfish Asterina pectinifera. The cDNA sequences of Gαs, Gαi, Gαq and Gβ consisted of ORFs encoding 379, 354, 353 and 353 amino acids. The expression levels of Gαs were extremely low in follicle cells at stage IV, whereas the mRNA levels increased markedly in stage V. On contrary, the mRNA levels of Gαi were almost constant regardless of stage IV and V. These findings strongly suggest that de novo synthesis of Gαs-proteins is contributed to the action of GSS on follicle cells to produce 1-MeAde and cAMP.

Biosynthesis and biological action of pineal allopregnanolone

The pineal gland transduces photoperiodic changes to the neuroendocrine system by rhythmic secretion of melatonin. We recently provided new evidence that the pineal gland is a major neurosteroidogenic organ and actively produces a variety of neurosteroids de novo from cholesterol in birds. Notably, allopregnanolone is a major pineal neurosteroid that is far more actively produced in the pineal gland than the brain and secreted by the pineal gland in juvenile birds. Subsequently, we have demonstrated the biological action of pineal allopregnanolone on Purkinje cells in the cerebellum during development in juvenile birds. Pinealectomy (Px) induces apoptosis of Purkinje cells, whereas allopregnanolone administration to Px chicks prevents cell death. Furthermore, Px increases the number of Purkinje cells that express active caspase-3, a crucial mediator of apoptosis, and allopregnanolone administration to Px chicks decreases the number of Purkinje cells expressing active caspase-3. It thus appears that pineal allopregnanolone prevents cell death of Purkinje cells by suppressing the activity of caspase-3 during development. This paper highlights new aspects of the biosynthesis and biological action of pineal allopregnanolone.

157 LEUKEMIA INHIBITORY FACTOR IMPROVES OOCYTE MATURATION AND DEVELOPMENTAL COMPETENCE IN PIGS

A variety of growth factors and cytokines that are present in follicular fluid provide oocytes with a suitable environment for their maturation. One such cytokine is leukemia inhibitory factor (LIF). Although LIF-supplemented medium enhances embryo development in human, mouse, and bovine, studies investigating the effects of LIF on in vitro maturation (IVM) and subsequent embryo development are inconclusive. Additionally, the underlying mechanisms of LIF in oocyte maturation and embryo development after IVF have not been studied yet. In the present study, we examined the effect of recombinant porcine LIF (pLIF), produced in our laboratory, on porcine oocyte maturation and the mechanism of how LIF involves in oocyte maturation process at molecular level. The biological activity of pLIF was evaluated by sustenance of mouse embryonic stem (ES) cells with an undifferentiating state in ES medium supplemented with pLIF, and the final concentration (1 : 200, equivalent to 1000 U mL–1 of mouse LIF) was determined by serial dilution. Porcine cumulus–oocyte complexes (COC) were cultured in modified NCSU-37 medium supplemented with pLIF during the first 22 h [pLIF (+, –)], the latter 22 h [pLIF (–, +)], or whole 44 h [pLIF (+, +)] of IVM and the proportion of metaphase II (M-II) stage oocytes was observed. Oocyte maturation was enhanced in each group by supplementation with pLIF [pLIF (+, –): 76.1%, n = 138; pLIF (–, +): 82.1%, n = 140; pLIF (+, +): 86.6%, n = 127], when compared with control [pLIF (–, –): 69.6%, n = 112], in which a significant increase of M-II rate (P < 0.05 by ANOVA) and cumulus expansion were observed in the pLIF (+, +) group. The effect of pLIF was only seen for COC but not for denuded oocytes. When oocytes were subjected to IVF (Kikuchi et al. 2002), those matured in pLIF (+, +)-supplemented medium demonstrated higher blastocyst developmental rates (21.1% v. 16.2%; P = 0.07) with increased cell numbers (50.2 cells v. 45.0 cells; P = 0.12) compared with pLIF (–, –) on Day 6 of embryo culture (IVF = 0). Examination of transcripts and proteins of the LIF signalling pathway revealed that mRNA and protein levels of LIF, LIF receptors, and signal transducer and activator of transcription 3 (STAT3) were similar in both pLIF (–, –) and pLIF (+, +) samples. However, notable phosphorylation of STAT3 was observed in the pLIF (+, +) sample. These results suggest that the LIF/STAT3-pathway is functional during oocyte maturation in pigs. Therefore, supplementation of maturation medium with pLIF could improve the developmental competence of oocytes by activation of this pathway. This project was supported by JSPS and HAS under the Japan-Hungary Research Cooperative Program.

44 PRODUCTION OF LIVE PIGLETS AFTER CRYOPRESERVATION OF IMMATURE PORCINE OOCYTES

Development to term of vitrified porcine follicular oocytes is reported in the present study. Immature cumulus-oocyte complexes (COC) were collected from slaughtered prepubertal gilts and were vitrified according to our method published recently (Somfai et al. 2013 J. Reprod. Dev., in press). Briefly, after pretreatment with 7.5 μg mL–1 of cytochalasin B (CB) for 30 min in modified NCSU-37 (a basic medium, BM) at 38.5°C, groups of 88 to 121 COC were equilibrated in a mixture of 2% ethylene glycol (EG), 2% propylene glycol (PG), and 7.5 μg mL–1 CB for 13 to 15 min. Then, COC were washed in vitrification solution (17.5% EG, 17.5% PG, 5% polyvinyl pyrrolidone, and 0.3 M trehalose in BM) and then dropped with 2 μL of vitrification solution onto the surface of aluminum foil floating on liquid nitrogen (LN2). Microdroplets (each containing 10–25 COC) were transferred into cryotubes. After storage in LN2 for 2 to 4 weeks, the oocytes were warmed by dropping the microdroplets directly into 2.5 mL of warming solution (0.4 M trehalose in BM) kept in a 35-mm Petri dish on a 42°C hotplate for less than 1 min. Then, the warming dish was placed on a 38°C hotplate and COC were consecutively transferred for 1-min periods into BM containing 0.2, 0.1, or 0.05 M trehalose at 38°C. The COC were matured in vitro for 44 h using porcine oocyte medium (POM) supplemented with 10% follicular fluid (Yoshioka et al. 2008 J. Reprod. Dev. 54, 208–213). Then, oocytes were denuded, and their live/dead status and nuclear maturation were determined by their morphology and the presence of the first polar body, respectively. To assess their developmental competence, vitrified and non-vitrified (control) oocytes were in vitro fertilized (IVF; Kikuchi et al. 2002 Biol. Reprod. 66, 1033–1041) and then in vitro cultured in porcine zygote medium-5 (PZM-5; Yoshioka et al. 2008 J. Reprod. Dev. 54, 208–213). Blastocyst rates were recorded on Days 5, 6, and 7 of culture (Day 0 = the day of IVF). The experiment was replicated 4 times. Data were analysed with 1-way ANOVA and the Tukey test. The results revealed that 86.4% (364/424) of oocytes survived after vitrification, which was significantly lower (P < 0.05) than that of controls [100% (326/326)]. Live oocytes in vitrified and control groups did not differ statistically in terms of nuclear maturation (63.9 v. 65.3%). Blastocyst rates of surviving vitrified oocytes were significantly lower compared with controls on Days 5 (2.4 v. 12.7%), 6 (4.8 v. 17.6%), and 7 (5.6 v. 18.4%). To test their ability to develop to term, 16 and 27 blastocysts on Day 5 developing from vitrified COC were transferred into 2 recipients. Both recipients became pregnant and farrowed a total of 10 live piglets (4 and 6 piglets, respectively). These data demonstrate that large groups of immature porcine oocytes could be cryopreserved by this method showing high survival and maturation rates. Furthermore, despite a low rate of blastocyst development, transfer of Day-5 blastocysts generated from vitrified oocytes resulted in piglet production for the first time in the world. Partially supported by JSPS and HAS under the Japan-Hungary Research Cooperative Program.

Brain and pineal 7α-hydroxypregnenolone stimulating locomotor activity: identification, mode of action and regulation of biosynthesis

Biologically active steroids synthesized in the central and peripheral nervous systems are termed neurosteroids. However, the biosynthetic pathways leading to the formation of neurosteroids are still incompletely elucidated. 7α-Hydroxypregnenolone, a novel bioactive neurosteroid stimulating locomotor activity, has been recently identified in the brain of newts and quail. Subsequently, the mode of action and regulation of biosynthesis of 7α-hydroxypregnenolone have been determined. Moreover, recent studies on birds have demonstrated that the pineal gland, an endocrine organ located close to the brain, is an important site of production of neurosteroids de novo from cholesterol. 7α-Hydroxypregnenolone is a major pineal neurosteroid that stimulates locomotor activity in juvenile chickens, connecting light-induced gene expression with locomotion. This review summarizes the advances in our understanding of the identification, mode of action and regulation of biosynthesis of brain and pineal 7α-hydroxypregnenolone, a potent stimulator of locomotor activity.

A genetically female brain is required for a regular reproductive cycle in chicken brain chimeras

Sexual differentiation leads to structural and behavioural differences between males and females. Here we investigate the intrinsic sex identity of the brain by constructing chicken chimeras in which the brain primordium is switched between male and female identities before gonadal development. We find that the female chimeras with male brains display delayed sexual maturation and irregular oviposition cycles, although their behaviour, plasma concentrations of sex steroids and luteinizing hormone levels are normal. The male chimeras with female brains show phenotypes similar to typical cocks. In the perinatal period, oestrogen concentrations in the genetically male brain are higher than those in the genetically female brain. Our study demonstrates that male brain cells retain male sex identity and do not differentiate into female cells to drive the normal oestrous cycle, even when situated in the female hormonal milieu. This is clear evidence for a sex-specific feature that develops independent of gonadal steroids.

New biosynthesis and biological actions of avian neurosteroids

De novo neurosteroidogenesis from cholesterol occurs in the brain of various avian species. However, the biosynthetic pathways leading to the formation of neurosteroids are still not completely elucidated. We have recently found that the avian brain produces 7α-hydroxypregnenolone, a novel bioactive neurosteroid that stimulates locomotor activity. Until recently, it was believed that neurosteroids are produced in neurons and glial cells in the central and peripheral nervous systems. However, our recent studies on birds have demonstrated that the pineal gland, an endocrine organ located close to the brain, is an important site of production of neurosteroids de novo from cholesterol. 7α-Hydroxypregnenolone is a major pineal neurosteroid that stimulates locomotor activity of juvenile birds, connecting light-induced gene expression with locomotion. The other major pineal neurosteroid allopregnanolone is involved in Purkinje cell survival during development. This paper highlights new aspects of neurosteroid synthesis and actions in birds.

47 DIFFERENCES IN MITOCHONDRIAL DNA COPY NUMBER AND EPIGENETIC PATTERNS OF MITOCHONDRIA-RELATED GENES IN CLONED COWS FROM THE SAME DONOR CELLS

The genetic codes of cloned animals and the donor are identical; however, incomplete reprogramming of donor nuclei during NT causes epigenetic abnormalities in cloned animals. Due to the genetic identity and epigenetic differences among clones, we can study epigenetic effects on the phenotypes by analyzing genetically identical clones. During the NT process, donor cell mitochondria (mt) are transferred into the recipient oocytes and mtDNA heteroplasmy is observed. Previous studies have reported various mtDNA transmission patterns not only in the cloned animal itself but also in the offspring of clones. However, differences in mtDNA copy number in cloned animals have not been reported, especially genetically identical ones. To analyze the genetic effects on mtDNA copy number in cattle, we compared actual mtDNA copy number per diploid genome in various tissues of clones derived from the same donor cells. From 5 genetically identical cloned cows (Japanese Black cattle, ages 68 to 82 months) and 6 non-cloned cows (Japanese Black cattle, ages 52 to 129 months), we isolated DNA from 8 kinds of tissues (heart, lung, liver, kidney, spleen, small intestine, muscle, and spinal cord) and measured mtDNA copy number by using real-time PCR. The absolute copy numbers of 2 mtDNA-encoded genes (COX1 and CytB) and 2 nuclear-encoded genes (H19 and IGF2) were measured and analyzed. To examine the epigenetic effects on mitochondria-related genes, we also analyzed DNA methylation patterns of mitochondria-related gene ANT4 (mitochondrial ADP-ATP translocase) in these tissues by the combined bisulfite restriction analysis (COBRA) method. The actual mtDNA copy number per diploid genome varied in tissues and individuals both in clones and non-clones (average in clones v. non-clones: heart: 11 839 ± 6210 v. 9569 ± 2555; lung: 2027 ± 1153 v. 1383 ± 173; liver: 5644 ± 2278 v. 4799 ± 1848; spleen: 1080 ± 844 v. 393 ± 265; kidney: 7034 ± 4448 v. 2939 ± 784; small intestine: 1330 ± 573 v. 437 ± 171; muscle: 9861 ± 3640 v. 7907 ± 3229; spinal cord: 3961 ± 1819 v. 2756 ± 496). The variability of mtDNA copy number in clones was significantly higher in the lung, spleen, kidney, small intestine, and spinal cord (P = 0.001, 0.026, 0.005, 0.021, and 0.014, respectively; F-test), but not in other tissues. Methylation of the ANT4 gene is quite tissue dependent: hypomethylated in the liver, muscle and spinal cord; moderately methylated in the heart, lung, and kidney; and highly methylated in the spleen and small intestine. The methylation patters of ANT4 were not different between clones and non-clones. These results suggest that mtDNA copy number is more influenced by nongenetic factors than genetic background.

299 A FEATURE OF SELF-RENEWAL PORCINE EMBRYONIC STEM CELL-LIKE CELL LINES ESTABLISHED BY INHIBITORS

Despite meticulous attempts for more than two decades, establishment of authentic porcine embryonic stem cell (ESC) from pig has never been successful. Although putative porcine ESC-like cells have been reported, such cell lines easily lose the ability of self-renewal, becoming extinct or differentiating after only a limited number of passages in culture. Porcine ESC-like cells exhibiting the property of self-renewal rather than pluripotency are considered a valuable resource in applications such as drug screening and toxicology testing in humans and livestock, and in veterinary medicine. In the present study, we evaluated the effect of glycogen synthase kinase 3β (GSK3β) inhibitor CHIR99021 and Erk signalling inhibitor PD184352 for use in establishing ESC-like cell lines derived from the inner cell mass (ICM) of porcine blastocysts produced in vitro. These ICM-derived cell lines were initially cultured and passaged in conventional human ES medium. They displayed so-called ESC-like morphology; for example, the isolated colonies began to grow as a monolayer with coarse cell–cell boundaries, in which the cells exhibited polygonal boundaries, high nuclear/cytoplasmic ratios, abundant lipid-like inclusions, alkaline phosphatase activity, and expression of markers of undifferentiated cells such as OCT4 and NANOG. After transfer to culture in ES medium containing the inhibitors, the morphology of the colony was dramatically changed, displaying a closely packed and smooth-edged colony with tight cell–cell boundaries. Remarkably, growth of the established cell lines is leukemia inhibitory factor (LIF)-dependent. The inclusion of inhibitors supports self-renewal, thus enabling continuous culture for over 100 passages while maintaining an undifferentiated state. High-passage-number cells continued to express undifferentiated marker genes and showed alkaline phosphatase activity and telomerase activity with an X chromosome status of XaXi. We further investigated the potential for differentiation of the established cell lines. The cells could easily form embryoid body-like spheres in suspension culture. When either the spheres or ESC-like cells were inoculated under the kidney or testis capsules of nude mice, classical teratoma formation was not observed after 2 to 3 months. However, histological analyses revealed apparent invasive proliferation derived from porcine cells. Although further analyses are required to characterise the property of the porcine ESC-like cells, we have recently succeeded in establishment of green fluorescent protein (GFP)-expressing stable cells lines, which will be useful for further investigation.

79 A COMBINATION OF ETHYLENE GLYCOL AND PROPYLENE GLYCOL IS SUPERIOR TO INDIVIDUAL CRYOPROTECTANTS FOR THE VITRIFICATION OF IMMATURE PORCINE OOCYTES

We compared the feasibility of ethylene glycol (EG) and propylene glycol (PG) for the vitrification of immature porcine cumulus–oocyte complexes (COC). Porcine COC collected from 3- to 6-mm follicles of slaughterhouse-derived ovaries were subjected to solid-surface vitrification (Somfai et al. 2010 Theriogenology 73, 147–156) either in 35% (v/v) EG or 35% (v/v) PG or in the mixture of 17.5% (v/v) EG and 17.5% (v/v) PG. After warming, the COC were subjected to in vitro maturation, IVF, and embryo culture according to Kikuchi et al. (2002 Biol. Reprod. 66, 1033–1041). Oocyte survival and maturation rates were assessed after in vitro maturation by evaluating membrane integrity and the extrusion of the first polar body. All live oocytes were subjected to IVF and in vitro culture. Cleavage and blastocyst rates were calculated from the total number of oocytes subjected to IVF on Day 2 (Day 0 = IVF) and Day 7, respectively. Total-cell (blastomeres) numbers in blastocysts were recorded on Day 7 after staining with Hoechst 33342. In Experiment 1, competence parameters of oocytes vitrified either in EG-based (EG group; n = 310) or a PG-based (PG group; n = 265) vitrification media were compared with those in the nonvitrified control (n = 160). The experiment was replicated 4 times. In Experiment 2, the competence parameters of oocytes vitrified with the combination of 17.5% EG and 17.5% PG (EG+PG group; n = 397) were compared with those in nonvitrified control (n = 245) and toxicity control (TC, exposed to cryoprotectants without cooling; n = 245) groups. Five replications were performed. Results were analyzed by ANOVA. Differences with P < 0.05 were considered significant. In Experiment 1, the mean survival rate of vitrified oocytes was significantly higher (P < 0.05) in 35% PG compared with that in 35% EG (73.3 and 25.9%, respectively). Maturation rates of surviving oocytes did not differ among vitrified (PG and EG) and nonvitrified control groups (71.1, 62.4, and 64.0%, respectively). After IVF of surviving oocytes, blastocyst formation rate in the group vitrified in EG was higher (P < 0.05) compared with that vitrified in PG but was lower (P < 0.05) compared with control (10.8, 2.0, and 25.0%, respectively). Mean cell numbers in blastocysts did not differ among EG, PG, and control groups (50.5, 47.7, and 48.7, respectively). In Experiment 2, survival of immature oocytes in the EG+PG group was 42.6%. After IVF, 10.7% of oocytes developed to the blastocyst stage in the EG+PG group, which was lower (P < 0.05) than those of the control (18.1%) and TC (23.3%) groups. Blastocyst rates in the control and TC groups were not statistically different. Mean cell numbers in blastocysts did not differ significantly among the EG+PG, control, and TC groups (61.6, 59.3, and 53.3, respectively). In conclusion, 35% PG provided a higher oocyte survival rate after vitrification compared with 35% EG. However, presumably due to toxic effects, 35% PG greatly reduced the development competence of oocytes. The combination of 17.5% EG and 17.5% PG yielded higher survival rates than did 35% EG, without any toxic effect on oocytes.

36 RESTORATION OF TELOMERE LENGTH IN CLONED PIG EMBRYOS DURING EARLY EMBRYOGENESIS IS NOT DEPENDENT ON TELOMERE LENGTH AND TYPE OF DONOR CELLS

Analyses on telomere length in cloned animals have revealed diverse results depending on the donor cell types. In mice and cattle, telomere length is reset during morula-blastocyst transition and the restoration is thought to be a telomerase-dependent process. However, it is still unknown whether the pattern of telomere elongation during this transition is dependent on donor cell types. In the present study, we examined the changes of telomere length during morula-blastocyst transition in cloned porcine embryos using different types of donor cell. Embryonic stem-like cells (ES), cumulus cells (C), fibroblasts at passages 7 and 10 (F7 and F10, respectively) were used as donor cells to produce NT embryos (ES, C, F7, and F10 groups, respectively). Telomere lengths of ES (35.8 ± 1.5 kb), C (24.4 ± 0.5 kb), P7 (18.7 ± 0.6 kb), and P10 (17.2 ± 0.1 kb) cells were significantly different. In contrast, cloned morulae in ES, C, F7, and F10 groups did not have any significant differences in telomere length (18.2 ± 0.3, 17.8 ± 0.7, 18.5 ± 0.3, and 18.4 ± 0.4 kb, respectively). Likewise, cloned blastocysts in ES, C, F7, and F10 groups had similar telomere length (22.3 ± 1.5, 23.5 ± 2.6, 20.2 ± 1.0, and 20.9 ± 1.0 kb, respectively). However, the telomere of the blastocyst was significantly longer (P < 0.05) compared with the morula in the respective group. Furthermore, relative telomerase activities of cloned morulae in ES, C, F7, and F10 groups (4.2 ± 0.4, 4.0 ± 0.5, 5.1 ± 0.4, and 4.9 ± 0.4, respectively) were significantly lower (P < 0.01) than those of cloned blastocysts in the same groups (8.2 ± 1.1, 8.6 ± 0.6, 12.5 ± 2.9, and 8.3 ± 1.1, respectively). The proportions of blastocysts in cloned embryos for ES, C, F7, and F10 groups (10.0 ± 5.2, 17.3 ± 2.9, 13.5 ± 2.9, and 13.1 ± 3.6%, respectively) did not significantly differ. Total cell numbers in blastocysts for ES, C, F7, and F10 groups (28.3 ± 2.9, 32.6 ± 3.6, 30.4 ± 3.1, and 27.4 ± 2.2, respectively) were not significantly different as well. In the present study, we found that the telomere elongation in cloned pig embryos occurs during morula-blastocyst transition. This is consistent with the previous findings in in vivo and in vitro fertilization and cloned embryos in cattle and mice. We also revealed that although different types of cells (ES, C, and F) or the same type of cells with different telomere length (F7 and F10) were used for NT, their resultant morulae and blastocysts had similar telomere length. This suggests that the telomere restoration during morula-blastocyst transition is independent of telomere length and type of donor cells. An increase in telomerase activity during morula-blastocyst transition indicates that the elongation of telomere length was likely a telomerase-dependent process. In conclusion, restoration of telomere length in cloned porcine embryos during morula-blastocyst transition was independent of telomere length and type of donor cells, and likely a telomerase-dependent process.

Biosynthesis and biological actions of pineal neurosteroids in domestic birds

The central and peripheral nervous systems have the capacity of synthesizing steroids de novo from cholesterol, the so-called 'neurosteroids'. De novo synthesis of neurosteroids from cholesterol appears to be a conserved property across the subphylum vertebrata. Until recently, it was generally believed that neurosteroids are produced in neurons and glial cells in the central and peripheral nervous systems. However, our recent studies on birds have demonstrated that the pineal gland, an endocrine organ located close to the brain, is an important site of production of neurosteroids de novo from cholesterol. 7α-Hydroxypregnenolone is a major pineal neurosteroid that stimulates locomotor activity of juvenile birds, connecting light-induced gene expression with locomotion. The other major pineal neurosteroid allopregnanolone is involved in Purkinje cell survival by suppressing the activity of caspase-3, a crucial mediator of apoptosis during cerebellar development. This review is an updated summary of the biosynthesis and biological actions of pineal neurosteroids.

Contribution of Leydig and Sertoli cells to testosterone production in mouse fetal testes

Testosterone is a final product of androgenic hormone biosynthesis, and Leydig cells are known to be the primary source of androgens. In the mammalian testis, two distinct populations of Leydig cells, the fetal and the adult Leydig cells, develop sequentially, and these two cell types differ both morphologically and functionally. It is well known that the adult Leydig cells maintain male reproductive function by producing testosterone. However, it has been controversial whether fetal Leydig cells can produce testosterone, and the synthetic pathway of testosterone in the fetal testis is not fully understood. In the present study, we generated transgenic mice in which enhanced green fluorescence protein was expressed under the control of a fetal Leydig cell-specific enhancer of the Ad4BP/SF-1 (Nr5a1) gene. The transgene construct was prepared by mutating the LIM homeodomain transcription factor (LHX9)-binding sequence in the promoter, which abolished promoter activity in the undifferentiated testicular cells. These transgenic mice were used to collect highly pure fetal Leydig cells. Gene expression and steroidogenic enzyme activities in the fetal Leydig cells as well as in the fetal Sertoli cells and adult Leydig cells were analyzed. Our results revealed that the fetal Leydig cells synthesize only androstenedione because they lack expression of Hsd17b3, and fetal Sertoli cells convert androstenedione to testosterone, whereas adult Leydig cells synthesize testosterone by themselves. The current study demonstrated that both Leydig and Sertoli cells are required for testosterone synthesis in the mouse fetal testis.

Estradiol promotes purkinje dendritic growth, spinogenesis, and synaptogenesis during neonatal life by inducing the expression of BDNF

Neurosteroids are synthesized de novo from cholesterol in the brain. In rodents, the Purkinje cell actively produces several kinds of neurosteroids including estradiol during neonatal life, when cerebellar neuronal circuit formation occurs. Estradiol may be involved in cerebellar neuronal circuit formation through promoting neuronal growth and synaptic contact, because the Purkinje cell expresses estrogen receptor-β. To test this hypothesis, in this study we examined the effect of estradiol on dendritic growth, spinogenesis, and synaptogenesis in the Purkinje cell using neonatal wild-type (WT) mice or cytochrome P450 aromatase knock-out (ArKO) mice. Administration of estradiol to neonatal WT or ArKO mice increased dendritic growth, spinogenesis, and synaptogenesis in the Purkinje cell. In contrast, WT mice treated with tamoxifen, an ER antagonist, or ArKO mice exhibited decreased Purkinje dendritic growth, spinogenesis, and synaptogenesis at the same neonatal period. Estrogen administration to neonatal WT or ArKO mice increased the expression of brain-derived neurotrophic factor (BDNF) in the cerebellum, whereas tamoxifen decreased the BDNF level in WT mice similar to ArKO mice. BDNF administration to tamoxifen-treated WT mice increased Purkinje dendritic growth. These results indicate that estradiol induces dendritic growth, spinogenesis, and synaptogenesis in the developing Purkinje cell via BDNF action during neonatal life.

Involvement of the neurosteroid 7α-hydroxypregnenolone in the courtship behavior of the male newt Cynops pyrrhogaster

Reproductive behavior in amphibians, as in other vertebrate animals, is controlled by multiple hormones. A neurosteroid, 7α-hydroxypregnenolone, has recently been found to enhance locomotor activity in the male newt, Cynops pyrrhogaster. Here, we show that this neurosteroid is also involved in enhancing the expression of courtship behavior. Intracerebroventricular (ICV) injection of 7α-hydroxypregnenolone enhanced courtship behavior dose-dependently in the sexually undeveloped males that had been pretreated with prolactin and gonadotropin, which is known to bring the males to a sexually developed state. But, unlike the case in the locomotion activity, 7α-hydroxypregnenolone did not elicit the behavior in males receiving no prior injections of these hormones. ICV administration of ketoconazole, an inhibitor of the steroidogenic enzyme cytochrome P450s, suppressed the spontaneously occurring courtship behavior in sexually active males. Supplementation with 7α-hydroxypregnenolone reversed the effect of ketoconazole in these animals. It was also demonstrated that the effect of the neurosteroid on the courtship behavior was blocked by a dopamine D2-like, but not by a D1-like, receptor antagonist. These results indicate that endogenous 7α-hydroxypregnenolone enhances the expression of the male courtship behavior through a dopaminergic system mediated by a D2-like receptor in the brain.

7α-Hydroxypregnenolone, a new key regulator of amphibian locomotion: discovery, progress and prospect

Seasonally-breeding amphibians have served as excellent animal models to investigate the biosynthesis and biological actions of neurosteroids. Previous studies have demonstrated that the brain of amphibians possesses key steroidogenic enzymes and produces pregnenolone, a precursor of steroid hormones, and other various neurosteroids. We recently found that the brain of seasonally-breeding newts actively produces 7α-hydroxypregnenolone, a previously undescribed amphibian neurosteroid. This novel amphibian neurosteroid acts as a neuronal modulator to stimulate locomotor activity in newts. Subsequently, the mode of action of 7α-hydroxypregnenolone has been demonstrated in the newt brain. 7α-Hydroxypregnenolone stimulates locomotor activity through activation of the dopaminergic system. To understand the functional significance of 7α-hydroxypregnenolone in the regulation of locomotor activity, diurnal and seasonal changes in synthesis of 7α-hydroxypregnenolone have also been demonstrated in the newt brain. Melatonin derived from the pineal gland and eyes regulates 7α-hydroxypregnenolone synthesis in the brain, thus inducing diurnal locomotor changes. Prolactin, an adenohypophyseal hormone, regulates 7α-hydroxypregnenolone synthesis in the brain, and also induces seasonal locomotor changes. In addition, 7α-hydroxypregnenolone mediates corticosterone action to increase locomotor activity under stress. This review summarizes the discovery, progress and prospect of 7α-hydroxypregnenolone, a new key regulator of amphibian locomotion.