Pallav Sengupta

Men and mice: Relating their ages

Since the late 18th century, the murine model has been widely used in biomedical research (about 59% of total animals used) as it is compact, cost-effective, and easily available, conserving almost 99% of human genes and physiologically resembling humans. Despite the similarities, mice have a diminutive lifespan compared to humans. In this study, we found that one human year is equivalent to nine mice days, although this is not the case when comparing the lifespan of mice versus humans taking the entire life at the same time without considering each phase separately. Therefore, the precise correlation of age at every point in their lifespan must be determined. Determining the age relation between mice and humans is necessary for setting up experimental murine models more analogous in age to humans. Thus, more accuracy can be obtained in the research outcome for humans of a specific age group, although current outcomes are based on mice of an approximate age. To fill this gap between approximation and accuracy, this review article is the first to establish a precise relation between mice age and human age, following our previous article, which explained the relation in ages of laboratory rats with humans in detail.

Environmental and occupational exposure of metals and their role in male reproductive functions

This review summarizes the effects of more than 20 metals that, research has indicated, may influence male reproductive health. Though males lack an apparent, easily measurable reproductive cycle, progress has been made in evaluating tests to identify chemical hazards and estimate reproductive health risks. Some agents discussed in this review are well known to have potential toxic effects on the male reproductive system, whereas some are not so well established in toxicology. This review attempts to cover most of the known toxicants and their effects on male fertility. The literature suggests a need for further research in those chemicals that are reactive and capable of covalent interactions in biological systems, as well as those defined as mutagens and/or carcinogens, to cause aneuploidy or other chromosomal aberrations, affect sperm motility in vitro, share hormonal activity or affect hormone action, and those that act directly or indirectly to affect the hypothalamo-pituitary-gonadal axis.

Environmental toxins: alarming impacts of pesticides on male fertility.

This review comprehensively summarizes the effects of more than 15 mostly used pesticides on male reproductive physiology, as recent experimental and epidemiological research have indicated their alarming impact on overall human health. Mechanisms have described that pesticide exposure damages spermatozoa, alter Sertoli or Leydig cell function, both in vitro and in vivo and thus affects semen quality. But, the literature suggests a need for more intricate research in those pesticides that are defined as mutagens or carcinogens and directly affect the hypothalamic–pituitary–gonadal axis. This literature review also proposes specific solutions to overcome these health effects.

Unilateral and bilateral cryptorchidism and its effect on the testicular morphology, histology, accessory sex organs, and sperm count in laboratory mice

BACKGROUND: Experimental unilateral cryptorchidism (ULC) and bilateral cryptorchidism (BLC) are excellent methods to study undescended testis in relation to spermatogenesis against a temperature gradient. OBJECTIVES: In case of ULC, it is possible to compare the testicular functions between normal condition and cryptorchidism in the same animal, whereas BLC shows the necessity of testicular androgens for proper maintenance of reproductive structures and functions. MATERIALS AND METHODS: In the present study, experimental ULC and BLC was done on same-aged adult mature male mice and kept for 15 days and 30 days, respectively, to observe the changes due to the induced cryptorchidism on the different reproductive organs, viz., the testis and accessory sex organs along with epididymal sperm count. Reproductive tissues were collected from individual animals and histopathological studies of testis were done to investigate different cytological changes. RESULTS: The size of the testes and accessory sex organs were found to be significantly reduced in BLC mice, whereas only testicular weight reduction was observed in ULC mice. Histopathological studies showed degenerative changes throughout the seminiferous tubules. CONCLUSION: Thus, the present investigation showed compensatory androgen production in ULC mice, whereas absence of androgen mediated reproductive functions in BLC animals.

Thyroid Function in Male Infertility

Thyroid gland, previously supposed not tohave any impact on spermatogenesis andmale fertility, are now being recognized ashaving important role in male reproduc-tive functions. Most of the studies on theeffectof thyroidhormonesonmalefertilitywereconductedbetweentheyears1970and2000 (1). The effects of thyroid hormonealterationsonthereproductivesystemhavebeen studied extensively in human sub-jects and animal models that have gener-ally shown that changes from normal thy-roid function resulted in decreased sexualactivity and fertility (2,3). The underly-ing mechanisms,however,are not constantthroughout all species, and results fromdifferent studies disagree (4).In rats rendered thyrotoxic by T4resulted in decreased serum gonadotropinlevels (5), decrease in total lipids, cho-lesterol, and phospholipids in testes, andsynthesize increased amounts of testos-terone(6).Inimmaturemalemiceagedlessthan 4weeks,the administration of slightlysupra-physiological T4 doses resulted ina tendency toward early maturation andshortening of development period. Con-versely, larger TH doses resulted indecreased testes weights and seminal vesi-cles, both in mice and rabbits (3). Directeffects of T4 resulted in minimal oxygenconsumption changes in testes when T4was present in testicular slice incubations(7). Finally, the effects of T4 on spermato-genesis are conflicting (8), but it wouldappear that T4 does not exert a direct effecton spermatogenesis in mature rats or rams(9). In rats, T3 affects testis maturation,and thyroid receptor (TR) type-1 (TR-1)expression in rats’ testes (10,11). Maxi-mal Sertoli cell proliferation coincides withmaximal T3 binding capacity in testis, sug-gesting that the main target of T3 action istheSertolicell.However,T3alsoplaysasig-nificant role in differentiation of the semi-niferous epithelium,and studies in rodentshave shown that T3 is an important factorin maturation of Leydig cells. The presenceof T3 is necessary to initiate differentiationof mesenchymal cells into Leydig progeni-torcells,andT3worksinconcertwithotherhormones [luteinizing hormone (LH) andIGF-I] to promote Leydig cell development(12). Data from other animal species (suchas deer, sheep, cattle, birds, and mink) alsosuggest that T3 is a component of the neu-roendocrine system that regulates seasonalcycles of reproductive activity (13). Theunderlying mechanisms postulate that T3triggers cessation of reproduction at theend of the reproduction season becausecirculating T3 levels in deer rise at thetime of seasonal transition to the non-breeding state and thyroidectomy resultsin the absence of seasonal regression ofthetestis(14,15).Hypothyroidisminducedor occurring soon after birth was associ-ated with marked sexual maturation anddevelopment delays in animals (16). Ratsmade hypothyroid transiently by propy-lthiouracil (PTU) administration showeda decrease in testicular size, retardation inSertoli cell differentiation, and prolonga-tion of Sertoli cell proliferation time (17).When the rats became older and returnedto a euthyroid status, there was an increaseintestissize,Sertolicellnumber,andspermproduction (18). In other studies whereexperimental hypothyroidism in rats andrams was left untreated for more than1month, there was an arrest of sexualmaturity, decreased testosterone concen-tration as well as an absence of libido andejaculate (6,19). It would therefore appearthat hypothyroidism affects the immature,but not the mature, testis. Pekary and Sat-tin (20) showed that both hypothyroidismand castration reduced TRH levels (20).The two most common types of thyroiddiseases are hypothyroidism and hyper-thyroidism. Studies assessing the role ofhypo- and hyperthyroidism in male infer-tility have also been conducted in humansubjects. Hypothyroidism may result ina decrease in the sex hormone bindingglobulin (SHBG) levels and a decreasein total serum testosterone levels, as wellas a decrease in the LH and the folliclestimulating hormone (FSH) levels (21). Incases of prolonged pre-pubertal hypothy-roidism due to drop in LH and FSH lev-els, the Leydig and Sertoli cells, respec-tively are less stimulated to differentiateinto mature cells, negatively affecting sper-matogenesis. This increases the number ofcells in the testes but decreases the num-ber of mature cells. Thus, in patients withhypothyroidism, increased testicular size isobserved along with a significant drop inmature germ cells within the seminifer-ous tubules (22,23). Fortunately, hypothy-roidism is very rare in males with anoccurrence rate of only 0.1% in the gen-eral population (21). Among the studieson human subjects, Corrales Hernandezet al. (24) analyzed blood and semen sam-ples of patients with primary hypothy-roidism (24). The study concluded thathypothyroidism adversely affected semenquality by compromising semen volumeand progressive sperm motility. Krassas

Male reproductive health and yoga

Now-a-days reproductive health problems along with infertility in male is very often observed. Various Assisted Reproductive Technologies have been introduced to solve the problem, but common people cannot afford the cost of such procedures. Various ayurvedic and other alternative medicines, along with regular yoga practice are proven to be not only effective to enhance the reproductive health in men to produce a successful pregnancy, but also to regulate sexual desire in men who practice celibacy. Yoga is reported to reduce stress and anxiety, improve autonomic functions by triggering neurohormonal mechanisms by the suppression of sympathetic activity, and even, today, several reports suggested regular yoga practice from childhood is beneficial for reproductive health. In this regard the present review is aimed to provide all the necessary information regarding the effectiveness of yoga practice to have a better reproductive health and to prevent infertility.

Metals and female reproductive toxicity.

Research into occupational exposure of metals and consequences of reproductive systems has made imperative scientific offerings in the preceding few decades. Early research works focused on possible effects on the reproductive functions rather than the complete reproductive health of the woman. Later, it was realized that metals, as reproductive toxins, may also induce hormonal changes affecting other facets of reproductive health such as the menstrual cycle, ovulation, and fertility. Concern is now shifting from considerations for the pregnant woman to the entire spectrum of occupational health threats and thus reproductive health among women.

Screening obesity by direct and derived anthropometric indices with evaluation of physical efficiency among female college students of Kolkata

Background: The available information regarding the obesity pattern of the undergraduate female students of Kolkata is inadequate, though there are several reports which indicate the complications and/or awful consequences of obesity on female health particularly, during the reproductive years. Aim: The present investigation has thus been carried out to report their present physiological status along with the prevalence of obesity, based on their body mass index (BMI), some direct and derived anthropometric indices, and physical fitness. Subjects and Methods: This small-scale cross-sectional study conducted in randomly selected 100 female students of different colleges of Kolkata with the age of 18-22 [mean age 20.4 (2.3)] years. Measurements of body composition included total 24 variables, with thirteen direct and eleven derived anthropometric variables; while physical efficiency parameters were physical fitness index, VO2max, energy expenditure and anaerobic power. The data of the experimental group were compared with those of the control group by t-test, using SPSS v.15.0 and MS-Excel v.2013. Results: Analysis of collected data showed majority of the students have normal range of BMI (67.95%), but, 21.95% of students found to be overweight and 3.84% are obese. They also showed higher fat mass [14.40 (4.11)], but, lower waist-to-hip ratio and conicity index. They were found to have poor to moderate physical fitness [57.60 (3.90)] and higher energy expenditure [5.61 (0.72)]. Conclusion: The findings of the present obesity screening reports almost one of four female students (24 out of 100 participants) are overweight/obese, indicated higher body fat distribution and increased propensity of being obese with age. Thus, the overall data along with their low physical fitness points out to health risks among female undergraduates of Kolkata.

The Disappearing Sperms: Analysis of Reports Published Between 1980 and 2015

Reports regarding the changes in sperm concentration in different counties of the world are inconsistent. Furthermore, the reports that sprung up from specific epidemiological and experimental examinations did not include data of prior studies or geographical variations. The current study, following a previous report of massive fall in semen volume over the past 33 years, attempts to delineate the trend of altering sperm concentrations and factors responsible for this by reviewing article published from 1980 to July 2015 with geographic differences. The current study identified an overall 57% diminution in mean sperm concentration over the past 35 years (r = −.313, p = .0002), which, when analyzed for each geographical region, identified a significant decline in North America, Europe, Asia, and Africa. An increasing trend of sperm concentration was identified only in Australia. The association of male age with such a trend (R2 = .979) is reported. The authors also correlated male fertility with sperm concentration. Thus, this comprehensive, evidence-based literature review aims to concisely and systematically present the available data on sperm concentration from 1980 to 2015, as well as to statistically analyze the same and correlate male health with the declining pattern of sperm count in a single scientific review to serve the scientific research zone related to reproductive health. It points to the threat of male infertility in times ahead.

Decline in sperm count in European men during the past 50 years

Purpose: To investigate whether the sperm concentration of European men is deteriorating over the past 50 years of time. Materials and Methods: We analysed the data published in English language articles in the past 50 years in altering sperm concentration in European men. Results: A time-dependent decline of sperm concentration (r = −0.307, p = 0.02) in the last 50 years and an overall 32.5% decrease in mean sperm concentration was noted. Conclusion: This comprehensive, evidence-based meta-analysis concisely presents the evidence of decreased sperm concentration in European male over the past 50 years to serve the scientific research zone related to male reproductive health.