Pyridoxine regulates hair follicle development via the PI3K/Akt, Wnt and Notch signalling pathways in rex rabbits

This study was conducted to evaluate the effect of pyridoxine on the development of hair follicles in Rex rabbits and the underlying molecular mechanism.Two hundred 3-month-old Rex rabbits were randomly divided into 5 groups and fed diets supplemented with 0,5,10,20,or 40 mg/kg pyridoxine.The hair follicle density on the dorsal skin and the gene and protein expression levels of components of the phosphoinositide 3-kinase(PI3 K)/protein kinase B(PKB or Akt),Wnt,Notch and bone morphogenetic protein(BMP)signalling pathways were measured.In addition,free hair follicles were isolated from Rex rabbits and cultured with pyridoxine in vitro to measure hair shaft growth.Furthermore,dermal papilla cells(DPC)were isolated from the skin of Rex rabbits and cultured with pyridoxine in vitro to measure the gene and protein expression levels of components of the PI3 K/Akt,Wnt,Notch and BMP signalling pathways.The results showed that the addition of dietary pyridoxine significantly increased the total follicle density,secondary follicle density,and secondary-to-primary ratio(S/P,P<0.05),that the growth ratio of hair stems was promoted by pyridoxine in basic culture medium,and that the growth length of tentacle hair follicles cultured in the pyridoxine group was longer than that in the control group(P<0.05).In addition,pyridoxine changed the DPC cycle progression and promoted cell proliferation,and appropriate concentrations of pyridoxine(10 and 20μmol/L)significantly inhibited cell apoptosis(P<0.05).Pyridoxine significantly affected the gene expression of components of the PI3 K/Akt,Wnt and Notch signalling pathways in the skin and DPC of Rex rabbits(P<0.05),increased the levels of phosphorylated catenin beta 1(CTNNB1)and Akt,and decreased the level of phosphorylated glycogen synthase kinase 3 beta(GSK-3β)(P<0.05).Therefore,the molecular mechanism by which pyridoxine promotes hair follicle density in Rex rabbits probably occurs through activation of the PI3 K/Akt,Wnt and Notch signalling pathways,prolonging hair follicle growth and delaying the onset of telogen.

Methionine Levels in the Diet for Pregnant Female Rabbits Affects Hair Follicles Development of Baby Rabbits

[ Objective] This experiment was conducted to study methionine level in diet for prepnant famale rabbits on the development of hair follicles of baby rabbits. [ Method] Fifty-four Angora female rabbits with similar body weight, parities and historicaly hair yield were randomly assigned to three groups with eighteen replicates in each group and one rabbit per replicate. Rabbits during pregnancy were fed diets with 0.5!%, 0.71% and 0.91% methionine, respectively. Hair follicle density and diameter in the back skin were determined at 18-day fetus. 26-day fetus, newborn and 2- month-old,and hair fiber diameter at 2-month-old was also determined. [ Result] The results showed as follows： （1） hair follicle density and diameter at each stage,coarse hair fiber diameter at 2-month. old showed a tendency of increasing with dietary methionine level（ P 〉0.05）, fine hair diameter in 0.91% group was significantly larger than that in 0.51% group at 2-month-old （ P 〈 0.05）. （2） With the development of baby rabbit,the ratio of secondary follicle and primary follicle increased gradually, at newborn of rabbits in group 0.51%, 0.71% and 0.91%were 5.84, 5.56 and 5.81, respectively, and at 2-month-old were 8.47, 7.97 and 8.03, respectively. （3） Baby rabbits in group 0.51%, 0.71% and 0.91% gained increases of primary follicle diameter by 0.58, 0.57 and 0.61pm/d from 26-day fetus to birth, and 0.11,0.11 and 0.12 prn/d from birth to 2-month-old, re- spectively; they also gained increases on secondary follicle diameter by 0.0018,0. 012 and 0. 011prn/d from birth to 2-months-old, respectively. [ Conclusion] These results indicate that increase of methionine level in diet for female rabbits during pregnancy is a stimulation factor for the development of hair follicle of baby rabbits, and can improve their hair fiber diameter.

In-vitro Maturation of Immature Oocytes from Preantral Follicles in Prepuberal Mice

Objective To observe the morphological changes in in vitro growth of preantral follicle isolated from prepuberal mice and to assess impacts of gonadotropin （Gn）, insulin transferrin selenium （ITS） and epidermal growth factor （EGF） on their development. Methods Early preantral mice follicles （90-130μm diameter） were mechanical isolated and selected from 2 weeks＇ old mice and then cultured in alpha-minimal essential medium （α-MEM） with or without Gn, ITS and EGF. The preantral follicles were cultured singly in 20 miovliters droplets for up to 14 d. The medium was replaced and the .follicles were observed everyday. Granulosa cells （GC） prolification, antrum formation and oocyte maturation were recorded. Results The medium with Gn supported preantral follicle culture in vitro, during which they retained a three-dimensional structure, maintained oocytes viability and increased in diameter and number of somatic cells＇. Preantral follicles cultured in Gn medium grew obviously, while those without Gn grew slowly and after 6 d＇s culture began to shrink and blacken. Significant increase in survival rate and maturation rate of oocytes was observed in Gn group （P〈0.01）, with 92.9% survived and 28.7%formed an antrum. Further supplementation of the Gn medium with ITS and rLH, resulted in the significant increase in survival and maturation of preantral follicle （P〈0.05） Conclusions α-MEM can be the medium for in vitro culture （IVC） of preantral follicles, but need to be added with rLH/rFSH, rHCG/rEGF to facilitate thecal cell attachment, GC proliferation and oocyte maturation.

Influence of Isoflurane Exposure for 15 Consecutive Days on Ovarian Function in Adult Female Mice

Female infertility after occupational exposure to inhaled anesthetic agents has attracted critical attention,but systematic studies focusing on the impact of inhaled anesthetics on the female reproductive system have not been well-established.We used a murine model to study the effect of isoflurane exposure on infertility in female adult mice and investigated the potential underlying mechanism.One hundred adult female C57 mice were randomly allocated into 5 groups exposed in air containing 0,2500,5000,10000 or 20000 ppm isoflurane for 15 consecutive days.Estrous cycle length was measured based on vaginal smear examination,ovarian histopathologic enumeration of follicles,and serum estradiol(E2),anti-Mullerian hormone(AMH),follicle-stimulating hormone(FSH),and luteinizing hormone(LH)levels to assess the effect of isoflurane on ovarian reserve.Compared to the control group,significant prolongation of the estrous cycle of the adult female mice was observed in the 20000 ppm isoflurane exposure group.Serum AMH was significantly decreased,and FSH and LH levels profoundly increased in the 5000,10000,and 20000 ppm isoflurane exposure groups compared to the control group.The histopathologic examination revealed a reduced number of developing follicles and an increased number of atretic follicles after isoflurane exposure,but the difference was not statistically significant.Thus,exposure to a higher concentration of isoflurane might have an adverse effect on ovarian reserve in sexually-mature female mice.

Wnt and the First Dermal Signal Initiating Embryonic Hair Development:A Mini-review

The molecular mechanisms of hair initiation and growth is one of the long-standing research programs in developmental biology.It has been suggested that for decades the existence of an inducing factor in the dermis that is required for the initiation of hair development.Furthermore,various signaling families are involved in the reciprocal interactions between epidermis and dermis during hair follicle initiation and morphogenesis.Among them,the wingless-type MMTV integration site family(Wnt)is probably the earliest and most critical regulator.This review primarily focuses on the role of Wnt signaling in hair follicle induction and its relationship with the first dermal signal that initiates embryonic hair development.