Expression of Nerve Growth Factor and Its Receptor TrkA in the Reproductive System of Adult Zebrafish

Abstract

Nerve growth factor (NGF), a member of the neurotrophin family, has emerged as an active mediator in different crucial events in the peripheral and central nervous system. At the same time, several studies showed that this neurotrophin can also play a role in non-neuronal tissues (e.g., among gonads). In spite of a large number of studies present in mammals, investigations devoted to NGF and its receptor TrkA in the reproductive system of other animal models, such as teleost fish, are scarce. To increase our knowledge of NGF and its receptor in a vertebrate gonads model, the present report describes the expression patterns of ngf and trka mRNA in the testis and ovary of adult zebrafish. By using chromogenic and fluorescence in situ hybridization, we demonstrate that in the testis of adult zebrafish, ngf and its receptor trka are mainly expressed in spermatogony B and spermatocytes. In the ovary of this fish, ngf and trka are expressed at different stages of oocyte development. Altogether, these results show that this neurotrophin and its receptor have an important role in the reproductive system that is conserved during vertebrate evolution.

Transcription Pattern of Neurotrophic Factors and Their Receptors in Adult Zebrafish Spinal Cord

“…The present study was conducted on adult males and females (1 year) of Danio rerio , zebrafish, obtained from a local furnisher and recently analyzed for other purposes, as described in our recently published study [ 36 ]. The animals were housed in a zebrafish aquarium under standard photoperiod conditions (14 h light and 10 h dark) and temperature (28 °C).…”

“…All digoxigenin (DIG)-labeled antisense riboprobes were generated using the protocol described in our previous studies [ 36 , 61 ] In detail, we produced the following riboprobes: bdnf , ngf , nt3 , nt4/5 , trka , trkb1 , and trkc1 . No probe was produced for nt6/7 , trkb2 , and trkc2 , for they were undetected by qPCR.…”

“…In the transverse section of spinal cord, two regions are clearly distinct, central and peripheral. In adult zebrafish, neurotrophins and their receptors were extensively described in different tissues and organs: the brain, kidney, ovary, testis, and the sensory and olfactory organs [ 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ]. However, there are no extensive studies regarding the specific identification and quantification of the mRNA localization pattern of neurotrophins and their receptors in the adult zebrafish spinal cord.…”

NGF and the Male Reproductive System: Potential Clinical Applications in Infertility

“…A recent study carried out on llamas suggests that the NGF contained in sperm has a seminal plasma origin; in fact, the NGF has been detected in ejaculated sperm, whereas it is not present in epididymal germ cells [ 180 ]. The NGF exerts its main effects on sperm traits through binding to its receptors, TrkA and p75NTR [ 181 ]. The activation of these receptors might also be involved in spermatogenesis and testicular development; in fact, the expression of NGF receptors in Leydig and Sertoli cells has been demonstrated [ 182 ].…”

Analysis of the Expression of Neurotrophins and Their Receptors in Adult Zebrafish Kidney

“…The binding to three distinct tyrosine kinase receptors, TrkA, TrkB, and TrkC, mediates their activities concerning neuronal proliferation [8], survival [9,10], differentiation, and plasticity [11] in many neuronal populations of the central and peripheral nervous systems in different vertebrates [12][13][14][15][16]. In mammals, as in fish, besides this essential role, neurotrophins and receptors are also important in non-neuronal cells, as suggested by their detection in different organs [17][18][19][20][21][22][23], including the kidney [24][25][26]. Neurotrophins and receptors are involved in different events to ensure the correct functioning of the kidney, such as growth, differentiation, and regulation of renal tubule transport.…”