The Positive Effects of Anabolic-Androgenic Steroids on Libido (Part 2: Men)

Introduction

In the realm of sports, bodybuilding, supplements, and steroid usage, there is a complex relationship between these elements and their influence on libido. This two-part series delves into the impact of androgens on sexual desire in both men and women. This first installment focuses on men, while the second part explores the effects on women. Additionally, we will examine nandrolone as an exception to the generally positive influence of androgens on libido and discuss the potential mechanisms behind its unique impact. Moreover, we'll explore the role of dopamine, a neurotransmitter, and its relevance to the suppression of libido attributed to nandrolone. We will also introduce a novel perspective on how nandrolone may contribute to reduced libido through altered dopamine metabolism.

Male Libido and Androgens

In men, natural androgens like testosterone (T) and its derivative, DHT, play a pivotal role in shaping sexual behavior and desire. From the onset of spermarche (the first ejaculation) through puberty, testosterone exhibits a profound influence on sexual desire or libido. As puberty unfolds, there is an astonishing 18-fold increase in endogenous testosterone concentrations in males.

Men tend to display higher libido levels compared to women, a distinction acknowledged by researchers and the general public alike. Despite this consensus, conflicting evidence exists in the literature regarding the precise impact of androgens on libido, particularly in women. We will explore the effects of androgens on female libido in the second part of this series.

Threshold Effect

It is widely accepted in the medical community that testosterone replacement therapy (TRT) can alleviate symptoms of low libido, especially in hypogonadal men, unless there are underlying organic issues affecting sexual function.

Medical experts generally view testosterone levels in men through the lens of a threshold effect. This means that there is a baseline range of normal total testosterone (TT) and free testosterone (fT) concentrations. Below this baseline, adverse effects on libido and sexual function are more likely to occur, whereas above it, few behavioral changes are typically observed.

TRT has been effective in relieving symptoms of hypogonadism, including low libido. However, it's important to note that TRT is often prescribed to older, otherwise healthy men in stable relationships, which naturally leads to increased opportunities for sexual activity. Cultural factors also come into play, as different societies have varying attitudes towards masturbation and its frequency, which can affect measurements of changes in libido.

Is There a "Ceiling Effect" for Androgen's Impact on Libido?

Research indicates that there may not be a theoretical upper limit, or ceiling, to the behavioral effects of androgens. Studies on healthy men have shown that even high-normal endogenous circulating androgen levels can lead to increased sexual interest and arousal.

For instance, a weekly dose of 200 mg of testosterone enanthate has been shown to enhance sexual interest in healthy men. Similarly, a daily dose of 240 mg of methyltestosterone increased sexual arousal in normal healthy men. Furthermore, male athletes using androgens for performance enhancement purposes engage in higher frequencies of sexual intercourse and achieve more weekly ejaculations compared to non-users.

The Role of Androgen Receptor Function in the Central Nervous System (CNS) in Males

Androgen Receptor Knockout (ARKO) models provide valuable insights into the function of testosterone and androgens in the CNS. In CNS tissues, the absence of the androgen receptor (AR) leads to male rodents behaving in ways that lack male sexual and aggressive behaviors.

This has implications for understanding the social construct of men typically taking the role of romantic pursuers and exhibiting aggression in intimate relationships. Evolutionary pressures and the human species' focus on reproduction likely contribute to men asserting their sexual roles, often tied to physical prowess.

The Desensitization Hypothesis

The Desensitization Hypothesis, to be covered in-depth in the second part of this series, proposes a theoretical model to explain the processes of behavioral desensitization to androgens in males. This desensitization is believed to result from the surge in testosterone during the perinatal period, potentially leading to maladaptive behaviors when testosterone levels increase significantly in adulthood.

Factors that may influence nandrolone's negative impact on libido include:

  1. Estrogens: Nandrolone often leads to sub-normal estrogen levels in men, which can affect libido. However, the relationship between estrogen levels and libido remains complex.
  2. 5α-Reduction to DHN: Nandrolone's androgenic potency is reduced in target organs compared to testosterone because it yields DHN (5α-dihydronandrolone) instead of the more potent DHT.
  3. Negative Feedback of Gonadotropins: Nandrolone can disrupt the regulation of gonadotropin secretion in the hypothalamic-pituitary-gonadal axis, affecting hormonal balance.
  4. Increased Dopamine Metabolism: Nandrolone may increase serum homovanillic acid (HVA), reflecting heightened dopamine metabolism, which could potentially reduce sexual arousal.

Dopamine and Libido

The excitatory system, primarily driven by brain dopamine (DA) systems, plays a central role in governing libido and sexual behaviors. Drugs that stimulate DA activity or inhibit other neurotransmitters like ECB or 5-HT can enhance libido.

Steroid hormones, including androgens and estrogens, influence libido by regulating the synthesis of enzymes and receptors in the DA, NE, MC, and OT neurochemical systems. These systems stimulate sexual arousal, attention, and behaviors while dampening inhibitory mechanisms that lead to sexual reward, sedation, and satiety.

In conclusion, endogenous androgens, such as testosterone and DHT, have a significant impact on male libido. Supraphysiological androgens tend to enhance libido in men, even those who are healthy. However, modifications to androgens can influence their effects on libido. Nandrolone stands as an exception, demonstrating a potential to diminish libido. Understanding the interplay between androgens, dopamine, and other neurotransmitters is crucial in unraveling the complexities of libido regulation.

The second part of this series will delve into the multifaceted dynamics of hormonal changes in women, affecting their libido, and explore various factors influencing female sexual desire.