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ORIGINAL ARTICLE

Apoptosis in epididymis of sand

Psammomys obesus, Cretzschmar, 1828:

Effects of seasonal variations, castration

and efferent duct ligation

L’apoptose dans l’épididyme du rat des sables itPsammomys

obesus, Cretzschmar, 1828 : effets des variations

saisonnières, castration et ligature des canaux efférents

a,b,∗ c a,b a

R. Menad , L. Lakabi , M. Fernini , S. Smaï ,

a d e

T. Gernigon Spychalowicz , F. Khammar , X. Bonnet ,

f f

E. Moudilou , J.M. Exbrayat

a

Small Vertebrates Reproduction, Laboratory of Research on Arid Areas, Faculty of Biological Sciences,

Houari Boumediene University of Sciences and Technology, DZ-16111 El Alia, Algiers,

b

Cellular Pathology and Biotherapy, Laboratory for Valorization and Bioengineering of Natural Resources,

Faculty of Sciences, Department of Natural and Life Sciences, University of Algiers, Algiers, Algeria

c

Production Laboratory, Protection of Endangered Species and Crops, Influence of Climatic Variations,

Faculty of Biological Sciences and Agronomic Sciences, Mouloud Mammeri University, BP 15000, Tizi Ouzou, Algeria

d

Endocrine Ecophysiology of Reproduction in Saharan , Laboratory of Research on Arid Areas,

Faculty of Biological Sciences, Houari Boumediene University of Sciences and Technology, El Alia, Algiers, Algeria

e

CEBC, UMR-7372 CNRS ULR, 79360 Villiers-en-Bois, France

f

Confluence Research Center—–Biosciences, Sciences and Humanities, Laboratory of Bioscience and

Technology, Ethics, Lyon Catholic University, 10, place des archives, 69288 Lyon Cedex 02, France

Received 16 July 2020 ; received in revised form 2 December 2020; accepted 20 December 2020

KEYWORDS Summary The aim of this study was to visualize apoptosis throughout the reproductive cycle

Apostain; and after castration, castration then treatment with testosterone, and ligation of efferent

ducts. The sand rat, obesus, Cretzschmar 1828, is a diurnal belonging to Cell death;

∗

Corresponding author: Cellular Pathology and Biotherapy, Laboratory for Valorization and Bioengineering of Natural Resources, Faculty

of Sciences, Department of Natural and Life Sciences, University of Algiers, Algiers, Algeria.

E-mail address: menadrafi[email protected] (R. Menad).

https://doi.org/10.1016/j.morpho.2020.12.007

1286-0115/© 2020 Elsevier Masson SAS. All rights reserved.

Please cite this article as: R. Menad, L. Lakabi, M. Fernini et al., Apoptosis in epididymis of sand rat Psam-

momys obesus, Cretzschmar, 1828: Effects of seasonal variations, castration and efferent duct ligation, Morphologie, https://doi.org/10.1016/j.morpho.2020.12.007

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MORPHO-480; No. of Pages 11 ARTICLE IN PRESS

R. Menad, L. Lakabi, M. Fernini et al.

the family Gerbillidae. Its breeding cycle is seasonal with reproduction in autumn, winter and

Season; early spring and a short resting period from late spring to early summer. Five groups of males

Androgen were studied: (1) captured during the breeding season; (2) animals captured during the

deprivation; resting season; (3) animals castrated and kept 30 days; (4) animals castrated, kept 30 days,

Principal cells and then treated with testosterone for 15 days; (5) animals subjected to the ligation of effer-

ent ducts and kept 30 days. Epididymis were removed and the presence of apoptotic cells was

explored using the ‘‘Apostain’’ immunohistochemical method. Histological results showed cell

and tissue remodeling. During the breeding season, a positive apoptotic signal was observed

mainly in smooth muscle cells of caput and cauda epididymis. This signal persisted throughout

the resting season. The orchiectomy induced apoptosis in almost of epithelial and connective

cells. However, this intense cell death was not reversed by treatment with testosterone. In ani-

mals that experienced efferent duct ligation, principal cells and smooth muscle cells showed a

positive signal for apoptosis. Our results converge to qualify the sand rat epididymis as an excel-

lent model for the study of apoptosis and argue for continued cell death, at least independent

of circulating testosterone levels.

© 2020 Elsevier Masson SAS. All rights reserved.

Résumé L’objectif de cette étude est la mise en évidence de l’apoptose dans l’épididyme du

rat des sables au cours du cycle de reproduction saisonnier et suite à des expérimentations,

castration, castration puis traitement par testostérone et ligature des canaux efférents. Le

modèle est le rat des sables, Psammomys obesus, Cretzschmar 1828, un rongeur déser-

ticole diurne présentant un cycle de reproduction saisonnier avec une période d’activité de

l’automne jusqu’au début du printemps, puis une période de repos sexuel limitée de la fin du

printemps au début de l’été. Cinq lots ont été constitués; le premier et le deuxième concernent

les animaux capturés en saison de reproduction et de repos sexuel respectivement. Le troisième

et le quatrième correspondent respectivement aux groupes d’animaux castrés depuis 30 jours,

et castrés depuis 30 jours puis traités pendant 15 jours à la testostérone. Le cinquième est le

groupe d’animaux ayant subi la ligature des canaux efférents pendant 30 jours. Après sacrifice

des animaux et prélèvement des épididymes proximaux et distaux, la recherche des cellules

apoptotiques a été effectuée par la technique immunohistochimique Apostain. Pendant la sai-

son de reproduction, un signal apoptotique positif est localisé principalement dans les cellules

musculaires lisses de tête et la queue de l’épididyme. Cette apoptose persiste pendant la sai-

son de repos sexuel. La castration induit une mort cellulaire concernant la plupart des cellules

épithéliales et conjonctives tandis que le traitement des animaux castrés ne prévient pas cette

dernière. Chez les animaux ligaturés, les cellules principales et les cellules musculaires lisses

sont positives. Il semblerait que l’apoptose soit un processus continu indépendant de la durée

de la castration et insensible à la testostérone. Malgré la diversité des éléments inducteurs

de l’apoptose retrouvés chez les différentes espèces, l’épididyme du rat des sables semble

constituer un très bon modèle pour l’étude de l’apoptose induite par la castration.

© 2020 Elsevier Masson SAS. Tous droits reserv´ es.´

Introduction The sand rat, Psammomys obesus, Cretzschmar 1828

(Gerbillinae), is a diurnal rodent living in the Alge-

rian Sahara. Reproduction is highly seasonal; breeding spans

Many mammalian species, spanning from large ungulates

from autumn to early spring and the resting period is lim-

to small , successfully adapted to the extremely

ited to late spring — early summer. This species has been

harsh environmental conditions that prevail in the most

used to study various physiological adaptations and different

arid of the planet [1,2]. In response to strong

metabolic disorders [5—9]. Investigations of seasonal varia-

climatic and food availability variations, they developed

tions of the reproductive system have shown cytological,

various morpho-functional, ethological and physiological

histological, biochemical and immunohistochemical remod-

reproductive strategies. The seasonal reproduction cycles

eling of the reproductive organs [8—19]. These results were

of Gerbillinae (16 genera, 103 different species) provide

consistent with seasonal hormonal fluctuations [20—24].

excellent examples of adaptive mechanisms that promote

The epididymis is a key organ involved in post-gonadal

parturition during the most favorable periods of the year

sperm storage and maturation that exhibits cyclical struc-

while large camelids rely on combined income and capital

tural changes. Sperm maturation essentially depends on the

breeding reproductive strategy to meet the demand of long

quality of the environment offered to spermatozoa, the

pregnancy and lactation [1—8].

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composition of the epididymal fluid, entirely regulated by resting (June-July) seasons at Béni Abbès in the southwest

epithelial cells with specific absorption and secretion func- of Algeria. After locating inhabited thanks to the

tions is thus crucial [25]. Previous studies have shown that presence of fresh tracks, traps were baited with small twigs

the epididymis of Psammomys obesus is sensitive to seasonal of Chenopodiaceae. Adult males were captured very early in

variations of androgens [16,26—28]. These steroids play a the morning. The animals were divided into 5 groups (Fig. 1):

cascading role by triggering in the epithelial cells, the tran-

scription and the translation of specific proteins secreted in

• animals caught during the breeding season between Jan-

the lumen that will affect the maturation of the spermato-

uary and March (group 01, n = 10); zoa [29,30].

•

animals caught during the resting season in June and July

In the epididymis, androgens can act directly via andro-

(group 02: n = 10). The three experimental groups were

gen receptors (AR) or after conversion to DHT by 5␣

caught during the animals were the breeding season and

reductase type I and II [31]. However, androgens can also

subjected to specific treatments;

exert their effect after irreversible conversion to 17␤ estra-

•

animals castrated and kept in captivity for 30 days

diol by P450 aromatase [32]. Estradiol regulates essential

(group 03: n = 8);

epididymal functions, through binding to estrogen recep-

•

animals castrated, kept in captivity for 30 days and

tors (ER␣) and (ER␤) that are dependent on ESR1 and ESR2

treated with testosterone for 15 days (group 04: n = 8);

gene activation. The importance of estrogen has been docu-

•

animals subjected to the ligation of their efferent ducts

mented in ER␣ mutant mice; infertile individuals exhibit an

kept in captivity for 30 days (group 05: n = 8).

abnormal epididymal phenotype characterized by delayed

absorption of epididymal fluid [33,34].

Androgen receptor (AR) and estrogen receptors (ER␣ and

The allocation of individuals in the five groups took into

␤

ER ) are nuclear receptors; they play the role of ligand sen-

account two main parameters: body mass and testicular

sor and factors at the same time. AR and ER

mass for castrated animals. In order to accurately iden-

bound to ligands undergo dimerization and bind to their hor-

tify the reproductive status of each individual, histological

mone response elements (ARE and ERE), a nucleic sequence

sections of the testis were performed. Animals with sper-

located at the level of the promoter of the targeted genes,

matozoa in the lumen of the seminiferous tubules were

and can either stimulate or repress gene expression [35]. In

considered as breeding. All animals were euthanized in the

Addition to this nuclear pathway, other non-genomic path-

morning by decapitation using a specially prepared labora-

ways were observed [36,37].

tory guillotine.

High levels of intra testicular androgen concentrations

(expressed as ng of androgens per g of testis) were observed

−1

in autumn and in winter ([testosterone] 7.6 ± 1.1 ng.g ;

−1 Castration and testosterone treatment of castrated

[androstenedione] 0.76 ± 0.11 ng.g ) whereas low values

animals

were reported in early summer (June) (testosterone:

1.5 ± 0.3; androstenedione: 0.20 ± 0.05); concentrations

Sand were operated under general anesthesia by inhala-

were raising in late July [4]. Annual variations of the testos-

tion of ether. After disinfection of the abdominal region, an

terone metabolic clearance rate (liters/24 h/100 g body wt)

incision was made in the front of the prepuce. The testes

were parallel to the changes of testicular androgens con-

and epididymis surmounted by adipose tissue were taken

centrations; clearance peaking in winter (6.7 ± 0.7) and

out. On each side, a wire ligature placed in the hilum of

decreasing in June (3.2 ± 0.3). Presumably, this contrasted

the gonad allowed the obstruction of the testicular artery

pattern of androgen production during the testis cycle

and of the efferent ducts while respecting the epididymal

should be reflected by marked seasonal differences in the

vascularization. The testicles freed from their adhesions

expression of endocrine receptors.

were removed. The epididymides were placed back into the

Considering the central role of androgenic hormones

scrotum. The abdominal incision was closed on both the

in regulating the structure and function of the sand rat

muscular and skin level with 4 to 5 stitches. The wound

epididymis, investigations of apoptotic process offer an

was disinfected and then coated with aqueous eosin. The

opportunity to better understand the interplay between sex-

injection of testosterone was made on group-4 animals after

ual steroids and seasonal remodeling and functioning of this

4 weeks of castration, by daily intramuscular injections (2

key reproductive organ. The aim of this work was to moni-

times a day) for 2 weeks of 75 ␮g of testosterone enanthate

tor the apoptotic process in the epididymis of Psammomys

diluted in 40 ␮l of olive oil [8,9].

obesus, Cretzschmar 1828, during the seasonal reproduc-

tion cycle and following complementary experiments: after

castration, castration then treatment with testosterone and

Ligation of efferent ducts

ligation of the efferent ducts.

The operation was performed on adult rats under the same

Material and methods conditions as for castrated animals. After extracting the

testis and epididymis from each side and isolating the testic-

Animals ular artery, the efferent ducts were ligated with a thread,

interrupting testicular flow to the epididymis. The testes

and epididymis were then placed back into the scrotum as

Male sand rats (Psammomys obesus, Cretzschmar 1828)

exposed above.

were captured during the breeding (December-January) and

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R. Menad, L. Lakabi, M. Fernini et al.

Figure 1 Experimental design.

Organ sampling denaturation. DNA is heat denatured in the presence of for-

mamide. The single-stranded DNA obtained is detected by

The organs were allocated to histology (transferred to hold- a specific monoclonal antibody (monoclonal anti-ssDNA F7-

ing baths after fixation with Bouin-Hollande’ fluid) or to 26/Apostain-ABC156). Apostain and TUNEL results are

western blot (placed in cryogenic tubes in liquid nitrogen) positively correlated [40]. However, Apostain is more sen-

examinations. sitive than the TUNEL method for distinguishing apoptotic

cells from necrotic cells. The unwaxed and hydrated sec-

tions were incubated in the saponin/proteinase K solution

Preparation of histological sections for 20 min at room temperature. After rinsing with distilled

water, the sections were embedded into a hydrophobic resin

◦

Samples underwent common steps: fixation, dehydration, by the Dako-pen, incubated at 58 C for 20 min in preheated

inclusion and staining followed by microscopic observation 50% formamide and then transferred for 5 min in PBS at

◦

[38,39]. The fixative used was Bouin-Hollande, the pieces 4 C. The slides were immersed for 15 min in 3% H2O2, rinsed

were immersed in a volume of 50 times greater than the for 5 min with PBS and then incubated in milk solution at

◦

organ’s volume. The duration of fixation ranged from two 3% preheated for 20 min at 37 C. After rinsing with PBS

to seven days. Samples were then dehydrated through suc- for 3 min, the mouse monoclonal antibody (Apostain) was

cessive immersions into increasing ethanol concentrations applied for 30 min in a humid chamber at room temperature.

(until 100% ethanol) and then transferred to toluene baths. On the negative controls, the antibody was replaced with

The duration of each bath was of 10 minutes. Samples were normal horse serum (Universal Vectastain Elite Kit). After

included in paraffin by immersion in molten paraffin in an rinsing 3 × 3 min in PBS, the biotinylated secondary anti-

◦

oven set at 58 C. Samples were immersed in two two-hour body was applied for 30 min at room temperature. This step

baths in glass crystallizers. They were removed from impreg- was followed by the application of the preformed avidin-

nation using heated forceps and then placed in Leuckart peroxidase complex for 30 min then visualization with DAB



bar molds containing hot and filtered paraffin. The block (Di-amino 3-3 -Benzidine) at room temperature and counter-

was demolded after complete cooling. The paraffin blocks staining with QS hematoxylin for 2 min. The sections were

␮

were then cut to 5 m thickness using a Leitz paraffin micro- then dehydrated and mounted in Eukit. Slides were observed

tome. Sections were retrieved using a brush and mounted and photographed on the Zeiss photomicroscope at different

needles and placed on ‘‘superfrost’’ slides covered with dis- magnifications using a Canon A80 digital camera or a Nikon

tilled water. The slides were subjected to a hot stage, which Eclipse E 400 microscope equipped with the DXM 1200 digital

allowed the tape to be spread and bonded to the slide. The camera.

◦

slides were dried out in an oven set at 40 C during 2 h, or

left for 48 h at room temperature.

Quantification of the apoptotic cells

The Apostain technique

The quantification was carried out by counting the main

Apostain is an immunostaining based on the increased positive cells by section. It was performed using ImageJ soft-

sensitivity of the DNA of apoptotic cells to thermal ware (Version 1.53a, National Institutes of Health, USA). We

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Figure 2 Apoptotic cells in caput epididymis of the sand rats (Psammomys obesus) during breeding and resting seasons. Breeding

season (a—f): (a) general view, (b) negative control, (c—f) a positive signal was observed in basal cells, smooth muscle cells,

fibroblasts and some principal cells. Resting season (l—d): (g) general view, h) negative control, (i & j) a positive signal was observed

in smooth muscle cells, basal cells and some principal cells. pc: principal cell, bc: basal cell, smc: smooth muscle cell, f: fibroblast,

spz: sperm. Blue triangle = positive signal; white triangle = negative signal.

selected sections cut transversely with a ratio of the two Results

perpendicular rays close to 1.

Caput epididymis

Statistical analysis

During the breeding season, Apostain technique revealed a

wide distribution of apoptotic cells, in smooth muscle cells,

Comparison of quantification levels was performed using fibroblasts and basal cells. In some epithelial sections, sev-

one-way analysis of variance (Anova) followed by Scheffe’s eral principal cells were also positive (Fig. 2a—f).

post hoc test. P-values less than 0.05 (P < 0.05) were consid- During the resting season, clear evidence of apoptosis

ered indicative of a significant difference. All calculations was observed in basal cells and smooth muscle cells, and to

were performed using OriginPro 8.0 software (OriginLab lesser extent in the principal cells and fibroblasts (Fig. 2g—j,

Corp., Northampton, MA, USA). Table 1). Indeed, among principal cells and fibroblasts some

were positive and others not (Fig. 2i—j).

The effect of castration was dramatic (Fig. 3a—d).

Ethical note Most epithelial and connective cells showed a positive

signal. In the epithelium, among abundant apoptotic prin-

cipal cells, few negative cells were observed (Fig. 3c—d,

All experiments complied with the Algerian legislation (Law

Table 1). The nucleus of several basal was positive.

Number 95—322/1995) inherent to protection of animals

Smooth muscle cells were immunoreactive. The fibrob-

designed to experimental and other scientific purposes as

lasts in the connective tissue were either positive or

well with the guidelines of the Algerian Association of

negative (Fig. 3c—d).

Experimental Animal Sciences (AASEA authorization num-

In castrated and testosterone treated animals (group 4),

ber 45/DGLPAG/DVA/SDA/14) relating to the protection of

evidence of apoptosis persisted in the caput epididymis, in

animals used for experimental and other scientific purposes.

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Table 1 Quantification of principal cells apoptotic by epithelial section.

Reproduction Rest Castrated Castrated +Testo Ligatured

Ep. Proximal 3.83 26.50 52.00 57.17 39.50

ESM 1.28 2.64 4.49 3.76 4.59

Significance ** *** *** ***

Ep. Distal 8.67 22.83 23.67 34.83 42.17

ESM 2.75 2.86 2.63 1.22 2.80

Significance ** ** *** ***

ESM: Standard Error.

*

P < 0.05.

**

P < 0.01.

***

P < 0.001.

Figure 3 Apoptotic cells in caput epididymis of sand rats subjected to experimentations: castration, castration and testosterone

treatment, ligation of efferent ducts. Castrated animals (a—d): (a) general view, (b) negative control, (c & d) a positive signal was

observed in most of the principal cells, basal cells and fibroblasts and in few principal cells. Some principal cells were negative.

Animals castrated then treated with testosterone (e—h): e) general view, (f) negative control, (g & h) all cells observed (principal

cells, basal cells, smooth muscle cells and fibroblasts) were immunoreactive. Animals that underwent efferent ducts ligation (i—l):

a positive signal was observed in most nuclei of the principal cells, basal cells, smooth muscle cells and fibroblasts. pc: principal

cell, bc: basal cell, smc: smooth muscle cell, f: fibroblast. Blue triangle = positive signal; white triangle = negative signal.

the principal, basal and smooth muscle cells and fibroblasts Cauda epididymis

(Fig. 3e—h, Table 1).

In animals with the efferent ducts ligated (group 5), as During the breeding season, in the proximal segment of

in breeding animals (group 1), immunostaining of apoptotic cauda, principal cells were negative but muscle cells were

cells showed a wide distribution in the principal, basal and positive. In the middle segment of cauda, principal and

smooth muscle cells, although several principal cells were basal cells were positive while clear cells were negative

negative (Fig. 3i—l, Table 1). (Fig. 4a—f). In the distal segment of cauda epididymis, 6

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Figure 4 Apoptotic cells in cauda epididymis of sand rat during breeding and resting seasons. Breeding season (a—f): (a) general

view, (b) negative control, (c-f) a positive signal was observed in basal cells, smooth muscle cells and some principal cells. Clear

cells were negative. The layer of smooth muscle cells showed a very intensive signal. Resting season (g—j): (g) general view, (h)

negative control, (I & j) a positive signal was observed in smooth muscle cells, basal cells and some principal cells. pc: principal

cell, bc: basal cell, smc: smooth muscle cell, f: fibroblast, cc: clear cell. Blue triangle = positive signal; white triangle = negative

signal.

intense labelling was localized in the smooth muscle cells Discussion

(Fig. 4e—f).

During the resting season, the immuno-histochemical sig-

We observed marked effects of season and of experimen-

nal was present in some principal and basal cells, but was

tal treatment on apoptosis of the main types of cells in

more expressed in the layers of smooth muscle cells sur-

the epididymis of the with differences between

rounding the epithelial tube (Fig. 4g—j, Table 1). In the

proximal and distal segments of this long duct (Fig. 6).

connective tissue, both positive and negative fibroblasts

During the breeding season, apoptotic signal was rarely

were found.

observed in principal cells, whereas smooth muscle cells,

In castrated animals, immunostaining concerned the

fibroblasts and basal cells were positive. During the rest-

nucleus of principal and basal cells. In the connective tissue,

ing season, apoptotic signal was mainly located in basal

Apostain reaction was weaker; some smooth muscle cells

cells and in smooth muscle layers, it was also observed in

and some fibroblasts were positive, others were negative

fibroblasts while weak evidence of apoptosis of the principal

(Fig. 5a—d, Table 1).

cells was observed (Fig. 6). In the liby-

In castrated and testosterone treated animals, immunos-

cus, a nocturnal rodent characterized by a drastic decrease

taining was observed in most principal cells (Fig. 5g—h).

of testosterone levels during the resting season, apoptosis

Between principal cells, clear cells did not present any pos-

assessed with TUNEL method revealed a considerable num-

itive signal (Fig. 5h). Basal and smooth muscle cells were

ber of apoptotic nuclei in the epithelial fraction [41].

immuno-reactive (Fig. 5g—h, Table 1).

Castration induced intense apoptotic effects in the prin-

In animals with the efferent ducts ligated, immunostain-

cipal cells of the caput and cauda epididymis (Fig. 6). This

ing was positive in the principal cells but negative in the

result matches previous studies in sand rats and merion

clear cells (Fig. 5i—1, Table 1).

where castration provoked a decrease of epididymal mass,

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Figure 5 Apoptotic cells in cauda epididymis of sand rat in castrated animals, castrated then treated animals with testosterone

and in animals that underwent efferent ducts ligation. Castrated animals (a—d): (a) general view, (b) negative control, (c & d)

a positive signal was observed in most principal cells, basal cells, smooth muscle cells and fibroblasts. Castrated animals then

treated with testosterone (e—h): (e) general view, (f) negative control, (g & h) most of the cells observed (principal cells, basal

cells, smooth muscle cells) were immunoreactive. Clear cells were negative. Animals that underwent efferent ducts ligation (i—l):,

(i) general view, (j) negative control, (k & l) a positive signal was observed in most nuclei of the principal cells and not in clear

cells. pc: principal cell, bc: basal cell, smc: smooth muscle cell, f: fibroblast, cc: clear cell. Blue triangle = positive signal; white

triangle = negative signal.

cell atrophy and tissue remodeling with disorganization of immediately after castration while in the current study it

the epididymal epithelium and the development of inter- was administrated two weeks later.

tubular connective tissue [42,43]. In male sand rats with ligated efferent ducts, apopto-

In Sprague-Dawley rats, a wave of apoptosis begins 18 h sis was less pronounced compared to castrated animals and

after castration in the caput and ends after a week in castrated then treated animals (Fig. 6). After ligation of the

the cauda epididymis [44]. More precisely, apoptosis first efferent ducts, the effects were less noticeable in the caput

observed in the caput peaked after 3 days and persisted epididymis and they were completely absent in the cauda

until the 5th day in this segment; in the cauda epididymis, epididymis [43]. In Sprague-Dawley rats, the ligation of the

apoptosis occurred after 5 days and peaked on the 6th day efferent ducts induced effects similar to castration in the

[44]. But in the sand rat, apoptosis persisted at least 30 initial segment [44]. In the absence of lumicrin factors, sev-

days after castration. Moreover, apoptosis persisted in indi- eral cells of the initial segment underwent apoptosis after

viduals castrated and then treated for 15 days, thus during 24 h [44]. Thus in the caput epididymis our results corrobo-

a total of 45 days (Fig. 6). Testosterone supplementation rate those obtained in the laboratory rat, but they contrast

did not prevent cell death. These results suggest that apop- with the cauda epididymis where apoptosis persisted.

tosis is a process at least partly independent of the time Molecules involved in apoptosis have been described in

elapsed after castration and of testosterone levels. These the epididymis of laboratory rodents, notably factors Bcl-

outcomes partly contrast with those obtained in laboratory 2 and Fas. Bcl-2 that exerts an anti-apoptotic role became

rats where orchidectomy triggered apoptosis but treatment undetectable 36 h after castration [44]; Fas (death recep-

with testosterone prevented it [44]. It should be noted, tor) associated with DNA fragmentation, appeared 48 h after

however, that testosterone treatment was administrated castration [46]. Likely, Fas pathway was involved since

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Conclusion

Beside the diversity of the factors inducing apoptosis across

species, empirical and experimental evidences suggest that

this process is involved in the regulation of the function-

ing of the epididymis, especially through remodeling of the

epithelium. In that respect, the marked seasonal changes

exhibited by the sand rat, and the strong responsiveness to

experimental treatments, show that this rodent represents

an excellent model to study the adaptive roles of apoptosis

during reproductive cycles.

Disclosure of interest

The authors declare that they have no competing interest.

Funding source

The Ministry of Higher Education and Scientific Research of

Algeria supported this work.

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