A previous study has shown that following castration of adult rats, neurally evoked contractions of their vasa deferentia were reduced in amplitude and resistant to α-adrenoceptor antagonists (MacDonald & McGrath, 1980). These and our current findings demonstrate the complex array of androgen actions on this tissue and its innervation during early development. However, while both pre- and postpubertal castration produced a decrease in total axonal volume within the rat vas deferens, there was an increase in the density of both sympathetic and parasympathetic axons (Keast et al. 2002). Prepubertal castration arrests development of the vasa deferentia whereas postpubertal castration produces a marked reduction in their size, so that they resemble those of prepubertal animals (Wakade et al. 1975; Calixto & Rae, 1981; Bustamante et al. 1989; Keast et al. 2002). The effects of pre or postpubertal castration on the rat vas deferens have been fairly extensively investigated (reviewed by Keast, 2006). Circulating androgens also increase during this period, to reach maximum around day 55 (McKinney & Desjardin, 1973).
This could indirectly influence testosterone levels, as poor sleep has been linked to lower testosterone levels. Magnesium is another essential mineral that has been shown to increase testosterone levels in men. Research has shown a correlation between low Vitamin D levels and low testosterone levels.
Nevertheless, more studies are needed to determine the exact hypothalamic sites and mechanisms of androgen action that promote metabolic homeostasis or metabolic dysfunction during male androgen deficiency and female androgen excess. The studies reviewed here demonstrate that testosterone acts in the CNS to differentially impact glucose homeostasis and energy balance in males and females. Women with PCOS exhibit increased gonadotropin-releasing hormone (GnRII) pulsatility, suggesting impairment of hypothalamic GnRH neurons.88 It is proposed that androgen activation of AR in ARC y-aminobutyric acid (GABA)ergic neurons upstream of GnRII neurons downregulates the progesterone receptor, whose activity leads to suppression of GnRH pulsatility.88 Perhaps AR action in these ARC neurons also contributes to metabolic dysfunction. Female global ARKO mice display normal metabolic phenotypes on a chow diet, yet they develop insulin resistance, glucose intolerance, and obesity when on a high-fat diet relative to normal mice on a high-fat diet.87 However, the authors did not explore if this obesity was due to increased food intake or decreased energy expenditure. The central effects of testosterone excess in adult females are summarized in Figure 1. Administration of DHT to adult female mice leads to insulin resistance and glucose intolerance.2 This effect is not observed in β-cell ARKO mice, suggesting that it is β-cell AR that is responsible for the metabolic dysfunction induced by androgen excess.2,85,86 Our lab is currently exploring if neuronal AR also contributes to androgen excess-induced metabolic dysfunction. Interestingly, androgen excess increased POMC intensity in neuronal bodies of the ARC while simultaneously decreasing the intensity of POMC projections to the DMH, suggesting that axonal transport of POMC from the soma to the nerve terminals was impaired.
When the listening session started, the participants were presented with one of the experimental sounds, types 1, 2, and 3, for 1 min. The sound pressure level (SPL) was modulated to 70 dB by measuring the maximum A-weighted SPL of these sounds in the slow mode. The use of different sound stimuli is important because sound-induced vasoconstriction would become habituated when the same sound stimulus is listened to repeatedly (Maltzman et al., 1979). These sounds can sufficiently induce a finger BVPR (Ooishi and Kashino, 2012). Next, the polarity of each type 1 sample was randomly flipped to disrupt the frequency structure of type 1, and the sound was filtered through a 20–20,000 Hz band pass filter in accordance with human aural characteristics. A fast Fourier transformation (FFT) was performed for each type 1 scratching sound. Other type 2 or 3 sounds were produced by MATLAB (The MathWorks, USA).
Studies on the direct effects of illicit drugs (CNS and PNS stimulants or depressants) on the male reproductive system described damage caused to the gonad, mainly after exposure to amphetamines, cocaine, opioids, and marijuana . The nerve fibers that reach the gonads, besides promoting crucial stimuli for testosterone production and during spermatogenesis, are responsible for the degenerative process of the testes in animals that have undergone vasectomy . Acetylcholine did not produce muscle contraction in humans, and in mice noradrenaline promoted muscle cell relaxation.