Prenatal undernutrition disrupted the sexual maturation, but not the sexual behavior, in male rats

Abstract

PurposeExposure to various stressors, including psychological, metabolic, and immune, in the perinatal period induces long‐lasting effects in physiological function and increase the risk of metabolic disorders in later life. In the present study, sexual maturation and sexual behavior were assessed in prenatally undernourished mature male rats.MethodsAll the pregnant rats were divided into the maternal normal nutrition (mNN) group and the maternal undernutrition (mUN) group. The mUN mothers received 50% of the amount of the daily food intake of the mNN mothers. Preputial separation and sexual behavior were observed in randomly selected pups of the mNN and mUN groups.ResultsThe body weight of the mothers was significantly lighter in the mUN group than in the mNN group. Similarly, the pups in the mUN group showed a significantly lower body weight than those in the mNN group from postnatal day (PND) 1 to PND 15. The preputial separation day was significantly delayed in the mUN group, compared to the mNN group. Sexual behavior did not show any significant difference between the two groups.ConclusionThese findings indicated that prenatal undernutrition delayed sexual maturation, but did not suppress sexual behavior, in mature male rats.

The influence of psychological stress in early life on sexual maturation and sexual behavior in male and female rats

“…In addition, the cognitive and reading abilities of the children of undernourished mothers were also lower than those of the children of normally nourished mothers . Furthermore, in rats we have shown that sexual maturation was disturbed in both the male and female offspring of undernourished mothers . These findings indicate that prenatal nutritional stress has adverse effects on physiological, psychological, and reproductive functions, and these changes might cause certain diseases in later life.…”

“…Newly purchased male and female rats (9 weeks of age) were used as partners for the sexual behavior test. In the sexual behavior test, a pair of rats was put in a cage together after the male had been allowed 5 minutes' habituation in the cage, and sexual behavior was monitored via a video recording for 30 minutes . Mounting (the male places its forequarters on the hindquarters of the female from behind), intromission (mounting with vaginal insertion), and ejaculation (mounting with vaginal insertion and emission) were evaluated as male sexual behaviors, and proceptive behavior (hopping and darting, ear wiggling) and receptive behavior (the lordosis quotient [LQ]: lordotic responses/mounts × 100, and the lordosis rating [LR]: the mean number of lordosis reflexes in the first 10 mounts) were evaluated as female sexual behaviors .…”

The reduction in sexual behavior induced by neonatal immune stress is not related to androgen levels in male rats

“…From PND35, the pups were inspected daily for preputial separation (PS), which is an indicator of male puberty. The penis was evaluated by examining and attempting to retract the prepuce to determine if it had separated from the glans penis (Stoker et al, 2000; Matsuzaki et al, 2017).…”

“…Two weeks later, estradiol benzoate (10 μg/body) dissolved in 0.1 mL sesame oil was injected subcutaneously (s.c.) into the backs of the female rats at 48 h and 24 h before the test session. Progesterone (1 mg/body) dissolved in 0.2 mL sesame oil was injected s.c. into the female rats 4 h before the test session (Govic et al, 2008; matsuzaki et al, 2017). At 11 and 12 weeks of age, sexual behavior tests were conducted under the following conditions.…”

“…In addition to metabolic functions, experiencing stress early in life can also have an impact on reproductive functions. We and others have reported that prenatal undernutrition delayed sexual maturation in male and female rats (Engelbregt et al, 2000; Iwasa et al, 2010a, b; Castellano et al, 2011; Matsuzaki et al, 2017), and immune stress in the early neonatal period delayed sexual maturation in male and female rats (Knox et al, 2009; Wu et al, 2011; Walker et al, 2011) and strongly suppressed the pulsatile secretion of gonadotropin‐releasing hormone (GnRH) after the administration of lipopolysaccharide (LPS) in adult male rats (Li et al, 2007). Furthermore, maternal separation in the early neonatal period, which is a form of psychological stress, reduced sexual behavior in male rats in adulthood (Rhees et al, 2001), and immune stress in the neonatal period downregulated sexual behavior in male and female rats in adulthood (Walker et al, 2011).…”