The ZRT Laboratory Blog

The ZRT Blog is an extensive resource for patients and health care providers searching for health and hormone testing information. Here, you can read about ZRT’s cutting edge research, advances in testing, wellness advice, and health industry highlights.



Dr. Thomas Guilliams

Thomas G. Guilliams, PhD, earned his doctorate from the Medical College of Wisconsin where he studied molecular immunology in the Microbiology Department. Since 1996, he has spent his time studying the mechanisms and actions of natural-based therapies, and is an expert in the therapeutic uses of nutritional supplements. As the VP of Science and Regulatory Affairs for Ortho Molecular Products, he has developed a wide array of products and programs which allow clinicians to use nutritional supplements and lifestyle interventions as safe, evidence-based and effective tools for a variety of patients. Dr. Guilliams teaches at the University of Wisconsin School of Pharmacy, where he holds an appointment as a Clinical Instructor, and at the University of Minnesota School of Pharmacy, and he is a faculty member of the Fellowship in Anti-aging Regenerative and Functional Medicine (A4M).
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Recent Posts

Neurotransmitters, Mood & the Perception of Stress - Part 3

Posted by Dr. Thomas Guilliams on Friday, 01 June

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This is part three of Dr. Guilliams's Neurotransmitters & Mood series. Part one can be found here. Part two can be found here.

Monoamines and the HPA Axis

The hypothalamus is directly innervated by neuronal systems that produce neurotransmitters, such as serotonin (5-HT), dopamine and norepinephrine (NE), that are involved in mood regulation and play various other roles in cognitive health. During the acute stress crisis, the mesolimbic dopaminergic reward system is stimulated to help maintain morale. However, during chronic stress or depression, the reward system is down-regulated by stress mediators, resulting in anhedonia.

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Neurotransmitters, Mood & the Perception of Stress - Part 2

Posted by Dr. Thomas Guilliams on Friday, 18 May

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This is part two of Dr. Guilliams's Neurotransmitters & Mood series. Part one can be found here. Part three can be found here.

Glutamate, GABA & Neurosteroid Activation

Glutamate (L-glutamic acid) and GABA (gamma-aminobutyric acid) are, respectively, the principal excitatory and inhibitory neurotransmitters in the CNS and play a significant role in HPA axis function and mood [1]. These two amino acid-based neurotransmitters account for over 50% of the synapses in the brain, while the monoamines (serotonin, norepinephrine and dopamine) account for only about 5% [2].

Glutamate is required for synaptic transmission and plasticity, and learning and memory. However, abnormal function of the glutamatergic system can lead to neurotoxicity, and has been implicated in the pathophysiology of several disorders, including amyotrophic lateral sclerosis (ALS), epilepsy, Huntington’s disease, Alzheimer’s disease, schizophrenia, depression and anxiety disorders [3].

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Neurotransmitters, Mood & the Perception of Stress

Posted by Dr. Thomas Guilliams on Friday, 06 April

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This is part one of Dr. Guilliams's Neurotransmitters & Mood series. Part two can be found here. Part three can be found here. 

When we talk about “stress,” or allostatic load, in terms of the perception of an event, we must realize that these “events” must first be translated into neurochemical signals before they trigger the HPA axis.

Therefore, the sensitivity and outcome of translating these events (whether they are ongoing events, memories of past events, or stressful anticipation of unrealized events), is highly dependent upon signaling from other neurotransmitters. In fact, the signaling neurotransmitters that manage mood and affect often overlap with measures of HPA axis activation, and cannot be easily distinguished in some subjects. [1]

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Re-assessing the Notion of "Pregnenolone Steal"

Posted by Dr. Thomas Guilliams on Wednesday, 21 June

ThinkstockPhotos-687447022-pregnenolone-.jpgWhen clinicians measure salivary cortisol and DHEA (DHEA-S) to assess stress and HPA axis function, it is common to find DHEA levels below the reference range in a number of individuals. A common explanation for the depletion of DHEA and other hormones (e.g., progesterone, testosterone) due to chronic stress is the phenomenon known as "pregnenolone steal."

The pregnenolone steal notion states that since all steroid hormones use pregnenolone (derived from cholesterol) as a precursor, the elevated secretion of cortisol caused by acute or chronic stress will inevitably result in less available pregnenolone to serve as a precursor for the production of DHEA and other down-stream hormones.

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