A Concept on the Interplay of Desire for Sex and Food in the Brain

Introduction

The Masturbation Diet is a fanciful way of describing the highly evolved balance in humans between the desire for and satisfaction with food vs the desire for and satisfaction with sex. It is not as some would contend a way to approach weight loss. 

The human brain is a complex network of neurons and circuits that regulate a myriad of behaviors essential for survival, including feeding and reproduction. Both sex and food are critical for the continuation of our species and individual survival, respectively. While they share common neurological pathways at certain levels of the brain, such as the mesolimbic dopamine system (more on this later), they are distinctly regulated at the hypothalamic level, the part of our brains that controls basic body functions like breathing, balance, and coordination, and simple survival urges like feeding, mating, and defense. Together, these parts–the brain stem, cerebellum, and basal ganglia–are casually referred to as our “lizard brain”. 

This brief review explores the dichotomous regulation of two desires, desires for food and desires for sex, highlighting the role of different brain regions, peptides, and neurotransmitters controlling whether you are hungry for food, or hungry aka “horny” for sex and why.

The Mesolimbic Dopamine System: A Common Pathway

The mesolimbic dopamine system in the brain is often referred to as the brain’s reward pathway. It is integral to the regulation of both sexual and feeding behaviors. This system includes the ventral tegmental area (VTA) and the nucleus accumbens (NAc), which are crucial for the processing of reward and motivation (see Figure 1)

Dopamine and Reward 

Dopamine, a key neurotransmitter in this pathway, is released in response to rewarding stimuli such as food and sex. This release promotes feelings of pleasure and reinforcement, driving the individual to seek out these stimuli again. The dopamine system’s activation by both food and sexual cues suggests a shared neural basis for these fundamental behaviors.

Figure 1: The Mesolimbic Dopamine System

Figure 1: Schematic representation of the mesolimbic dopamine system, highlighting the ventral tegmental area (VTA) and the nucleus accumbens (NAc). (Source: Wikimedia Commons)

The Hypothalamus: Distinct Control Centers

While the mesolimbic dopamine system provides a common pathway for the reward aspects of feeding and sex, the hypothalamus offers distinct regulatory mechanisms for these two distinct behaviors. The hypothalamus, located at the base of the brain, is a crucial center for homeostatic regulation, a mechanism by which we achieve physiological balance. Among these regulatory mechanisms are hunger for food, and desire for reproductive behaviors. In addition to feeding and sex, our focus here, the hypothalamus, is important for control of: thirst, hunger, water and food intake, heart rate, body temperature, blood pressure, sex drive, and emotional expression. It maintains learning and memory, and controls breastfeeding, just to name a few of its functions.

Feeding Behavior 

The arcuate nucleus (ARC) of the hypothalamus plays a pivotal role in regulating hunger for food. It contains two primary sets of neurons: orexigenic neurons, which promote feeding, and anorexigenic neurons, which inhibit feeding. Key peptides, or proteins, involved in this regulation include:

• Neuropeptide Y (NPY) and Agouti-related peptide (AgRP): These peptides are produced by orexigenic neurons and stimulate appetite.
• Pro-opiomelanocortin (POMC) and Cocaine- and Amphetamine-Regulated Transcript (CART): These peptides are produced by anorexigenic neurons and suppress appetite.

Sexual Behavior 

Sexual behavior is regulated by other regions of the hypothalamus, such as the medial preoptic area (mPOA) and the ventromedial hypothalamus (VMH). These areas are influenced by sex hormones (estrogen, progesterone, testosterone, etc.), and contain neurons that produce peptides and neurotransmitters involved in sexual desire, arousal and behavior.

Peptides and Neurotransmitters The interplay between feeding and sexual behavior is mediated by various peptides and neurotransmitters. For instance:

• Kisspeptin: A key regulator of puberty and fertility, kisspeptin neurons in the hypothalamus can also influence feeding behavior.
• Ghrelin: Known as the “hunger hormone,” ghrelin stimulates appetite and is also involved in modulating reproductive hormones.

This should suggest that there is some overlap between such regulatory messengers.

Inhibition and Reciprocity: Feeding vs. Sex

One fascinating aspect of hypothalamic regulation is the reciprocal inhibition of feeding and sexual behaviors. When the body is in a state of hunger, the need to acquire food suppresses reproductive behaviors, and vice versa.

Feeding Inhibits Sex When hunger is a priority, feeding-related peptides like NPY and AgRP are elevated, which can suppress sexual desire. This makes evolutionary sense, as obtaining food is essential for survival, and the energy required for sexual activity can be conserved until food is secured. Further, enough food and stored fat is required in women to support menstruation and the reproductive hormonal signals triggering sexual activity. 

Sex Inhibits Feeding Conversely, when sexual activity is prioritized, peptides like kisspeptin and neurotransmitters involved in sexual arousal can inhibit feeding behavior. This ensures that the body’s resources are allocated towards reproduction when conditions are favorable. 

Integration and Balance

The integration of feeding and sexual behaviors in the hypothalamus involves a delicate balance of signals. This balance is crucial for maintaining homeostasis and ensuring that both survival and reproductive needs are met appropriately.

Homeostatic vs. Hedonic Feeding 

Feeding behavior can be driven by homeostatic needs (energy balance) or hedonic pleasure (reward). The hypothalamus primarily regulates homeostatic feeding, while the mesolimbic dopamine system is more involved in hedonic feeding. Similarly, sexual behavior has both homeostatic (reproductive drive) and hedonic (pleasure) components.

Clinical Implications 

Understanding the neural regulation of feeding and sexual behaviors has significant clinical implications. Disorders such as obesity and anorexia can result from dysregulation of hypothalamic pathways. Similarly, sexual dysfunction can arise from hormonal imbalances or disruptions in hypothalamic function.

Pharmacological Targets 

Targeting specific peptides and neurotransmitters offers potential therapeutic avenues. For example, drugs that modulate NPY or AgRP signaling could help treat obesity, while those affecting kisspeptin might address certain reproductive disorders. Addressing the balance between these two could result in treatments to lose weight and increase sexual desire. (See: The Masturbation Diet: The Clinical Importance.)

Conclusion

The interplay between feeding and sexual behaviors in the brain exemplifies the complexity of neural regulation. While the mesolimbic dopamine system provides a common reward pathway, the hypothalamus distinctively controls these behaviors through various peptides and neurotransmitters. This reciprocal inhibition ensures that the body’s needs are met in a prioritized manner, balancing survival and reproduction. Understanding these mechanisms not only sheds light on fundamental human behaviors, but also offers insights into potential treatments for related disorders.

References

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