Neonatal inhalatory anesthetic exposure: reproductive changes in male rats

Beyond Genes: Germline Disruption in the Etiology of Autism Spectrum Disorders

Investigations into the etiology of autism spectrum disorders have been largely confined to two realms: variations in DNA sequence and somatic developmental exposures. Here we suggest a third route-disruption of the germline epigenome induced by exogenous toxicants during a parent's gamete development. Similar to cases of germline mutation, these molecular perturbations may produce dysregulated transcription of brain-related genes during fetal and early development, resulting in abnormal neurobehavioral phenotypes in offspring. Many types of exposures may have these impacts, and here we discuss examples of anesthetic gases, tobacco components, synthetic steroids, and valproic acid. Alterations in parental germline could help explain some unsolved phenomena of autism, including increased prevalence, missing heritability, skewed sex ratio, and heterogeneity of neurobiology and behavior.

General anesthesia, germ cells and the missing heritability of autism: an urgent need for research

Agents of general anesthesia (GA) are commonly employed in surgical, dental and diagnostic procedures to effectuate global suppression of the nervous system, but in addition to somatic targets, the subject's germ cells-from the embryonic primordial stage to the mature gametes-may likewise be exposed. Although GA is generally considered safe for most patients, evidence has accumulated that various compounds, in particular the synthetic volatile anesthetic gases (SVAGs) such as sevoflurane, can exert neurotoxic, genotoxic and epigenotoxic effects, with adverse consequences for cellular and genomic function in both somatic and germline cells. The purpose of this paper is to review the evidence demonstrating that GA, and in particular, SVAGs, may in some circumstances adversely impact the molecular program of germ cells, resulting in brain and behavioral pathology in the progeny born of the exposed cells. Further, we exhort the medical and scientific communities to undertake comprehensive experimental and epidemiological research programs to address this critical gap in risk assessment.

Hormone Inhibition During Mini-Puberty and Testicular Function in Male Rats

BACKGROUND

The mini-pubertal period of almost six hours in neonatal male rats is thought to be an important stage in sexual development.

OBJECTIVES

The aim of this study was to investigate the effect of hormone inhibition during mini-puberty on testicular function in male rats.

MATERIALS AND METHODS

We measured serum testosterone (T), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels in male rats at different time points after birth by enzyme linked immunosorbent assay (ELISA) and established a "no mini-puberty" model by ether inhalation. The mRNA expression levels of testicular androgen receptor (AR), insulin-like growth factor 3 (INSL3), anti-Mullerian hormone (AMH), and ghrelin were determined by real-time polymerase chain reaction (PCR) assays on postnatal days 45 and 75. Testicular tissue biopsies were stained with hematoxylin and eosin (H & E) and the structure, number and maturity of testis cells (including spermatogenic, Sertoli, and Leydig cells) were observed under microscopy at the same time.

RESULTS

Serum T and LH levels peaked at two hours after birth, while FSH peaked at hour 0, and bilateral testicular weight peaked at four hours after birth. The rats that underwent ether inhalation five minutes after birth had markedly reduced serum hormone levels. The mini-puberty model group revealed visible morphologic alterations in the tests on postnatal day 45. Then, on postnatal day 75, the mRNA expression level of AMH significantly decreased (P < 0.05) in the same group.

CONCLUSIONS

The inhibition of mini-puberty period in male rats was demonstrated to have an effect on their testicular function to some extent.

Effect of honey on the reproductive system of male rat offspring exposed to prenatal restraint stress

Exposure to prenatal stress is associated with impaired reproductive function in male rat offspring. Honey is traditionally used by the Malays for enhancement of fertility. The aim of this study was to determine the effect of honey on reproductive system of male rat offspring exposed to prenatal restraint stress. Dams were divided into four groups (n = 10/group): control, honey, stress and honey + stress groups. Dams from honey and honey + stress groups received oral honey (1.2 g kg(-1) body weight) daily from day 1 of pregnancy, meanwhile dams from stress and honey + stress groups were subjected to restraint stress (three times per day) from day 11 of pregnancy until delivery. At 10 weeks old, each male rat offspring was mated with a regular oestrus cycle female. Male sexual behaviour and reproductive performance were evaluated. Then, male rats were euthanised for assessment on reproductive parameters. Honey supplementation during prenatal restraint stress significantly increased testis and epididymis weights as well as improved the percentages of abnormal spermatozoa and sperm motility in male rat offspring. In conclusion, this study might suggest that supplementation of honey during pregnancy seems to reduce the adverse effects of restraint stress on reproductive organs weight and sperm parameters in male rat offspring.

Prenatal maternal restraint stress exposure alters the reproductive hormone profile and testis development of the rat male offspring

Several studies have demonstrated that the presence of stressors during pregnancy induces adverse effects on the neuroendocrine system of the offspring later in life. In the present work, we investigated the effects of early programming on the male reproductive system, employing a prenatal stress (PS) paradigm. This study found that when pregnant dams were placed in a plastic restrainer three times a day during the last week of pregnancy, the offspring showed reduced anogenital distance and delayed testicular descent. Serum luteinising hormone (LH) and follicle-stimulating hormone (FSH) levels were decreased at postnatal day (PND) 28 and testosterone was decreased at PND 75. Increased testosterone plus dihydrotestosterone (T + DHT) concentrations correlated with increased testicular 5α Reductase-1 (5αR-1) mRNA expression at PND 28. Moreover, PS accelerated spermatogenesis at PND 35 and 60, and increased mean seminiferous tubule diameter in pubertal offspring and reduced Leydig cell number was observed at PND 35 and 60. PS offspring had increased androgen receptor (AR) mRNA level at PND 28, and at PND 35 had increased the numbers of Sertoli cells immunopositive for AR. Overall, the results confirm that stress during gestation can induce long-term effects on the male offspring reproductive system. Of particular interest is the pre-pubertal imbalance of circulating hormones that probably trigger accelerated testicular development, followed by an increase in total androgens and a decrease in testosterone concentration during adulthood. Exposure to an unfavourable intrauterine environment might prepare for harsh external conditions by triggering early puberty, increasing reproductive potential.

EFFECTS OF EXPOSURE TO NEW INHALATIONAL ANESTHETICS ON SPERMATOGENESIS AND SPERM MORPHOLOGY IN RABBITS

The effects of chronic exposure to new inhalation anesthetics (sevoflurane and isoflurane) on spermatogenesis and sperm morphology were examined in 23 rabbits, randomly divided in 3 groups. Rabbits received 20 exposure hours (four hours/day x 5 days), as follows: group I: 2.3% (1.2 MAC) sevoflurane + 2L/min oxygen, group II: 1.3% (1.2 MAC) isoflurane + 2L/min oxygen, and group III (control): 2L/min oxygen. Semen was collected on the 12th, 19th, 26th, 33rd, and 41st days of exposure. Sperm concentration, motility and morphological changes were evaluated. On the 41st day, testicular biopsies were taken and observed with light microscopy. Sperm concentration and motility significantly decreased in the sevoflurane and the isoflurane groups, compared to control. There were no significant changes in the control group. It is concluded that chronic exposure to the new inhalational anesthetics had negative effects on spermatogenesis and sperm morphology.