Question: What naturally occurring neurotransmitter and a psychoactive drug did Andrew Luster use to commit multiple sexual assaults?

Context paragraphs:
Ibotenic acid: Ibotenic acid or ("S")-2-amino-2-(3-hydroxyisoxazol-5-yl)acetic acid, also referred to as ibotenate, is a chemical compound and psychoactive drug which occurs naturally in "Amanita muscaria" and related species of mushrooms typically found in the temperate and boreal regions of the northern hemisphere.  It is a conformationally-restricted analogue of the neurotransmitter glutamate, and due to its structural similarity to this neurotransmitter, acts as a non-selective glutamate receptor agonist.  Because of this, ibotenic acid can be a powerful neurotoxin, and is employed as a "brain-lesioning agent" through cranial injections in scientific research.

Gamma-Hydroxybutyric acid: γ-Hydroxybutyric acid (GHB), also known as 4-hydroxybutanoic acid, is a naturally occurring neurotransmitter and a psychoactive drug.  It is a precursor to GABA, glutamate, and glycine in certain brain areas, and it acts on the GHB receptor and it is a weak agonist at the GABA receptor.

Ki Database: The K Database (or K DB) is a public domain database of published binding affinities ("K") of drugs and chemical compounds for receptors, neurotransmitter transporters, ion channels, and enzymes.  The resource is maintained by the University of North Carolina at Chapel Hill and is funded by the NIMH Psychoactive Drug Screening Program and by a gift from the Heffter Research Institute.  s of 2010 , the database had data for 7449 compounds at 738 different receptors and, as of 27 2017 , 60104 "K" values.

Oxford child sex abuse ring: The Oxford child sex abuse ring was a group of seven men who, in May 2013, were convicted of sexual offences including rape, conspiracy to commit rape, arranging or facilitating child prostitution, trafficking for sexual exploitation, and procuring a miscarriage.  Their six underage victims were "subjected to sexual violence marked out by its sadism: sexual assaults designed to draw blood, multiple rapes, [and] physical attacks in which [they were] choked".  The girls were mainly white and all the abusers were not, leading to renewed discussion as to whether the crimes were racially motivated and whether the initial failure to investigate them was linked to the authorities' fear of being accused of racism.

Kamilah Willingham: Kamilah Willingham is an African American activist, feminist, speaker, and writer.  The focus of her activism centers on sexual assaults on college campuses as well as gender equality and civil rights.  She is best known for her appearance in the documentary “The Hunting Ground.”  She has also contributed essays to two novels on sexual assaults on college campuses.  Her work has garnered national attention through her collaboration with Lady Gaga and Vice President Joe Biden’s national campaign, “It’s On Us,” which raises awareness on sexual assault.  Willingham appeared on stage alongside Lady Gaga as she performed in the 2016 Grammy Awards.  Willingham currently lives in Los Angeles, California.

Serotonergic psychedelic: Serotonergic psychedelics (also known as serotonergic hallucinogens) are a subclass of psychedelic drugs with a method of action strongly tied to the neurotransmitter serotonin.  Serotonin (often referred to as 5-HT, short for its full chemical name "5-hydroxytryptamine") is a naturally occurring neurotransmitter which is tied to positive mood, certain involuntary muscle control, and countless other functions, many of which are not yet fully understood.

Randall Woodfield: Randall Brent "Randy" Woodfield (born December 26, 1950) is an American serial killer who was dubbed The I-5 Killer or The I-5 Bandit by the media due to the crimes he committed along the Interstate 5 corridor running through Washington, Oregon, and California.  Before his capture, the I-5 Killer was suspected of multiple sexual assaults and murders.  A native of Oregon, Woodfield was convicted of three murders and is suspected of killing up to 44 people.  He is currently incarcerated at the Oregon State Penitentiary.  In 2011, Woodfield was the subject of a Lifetime television movie "Hunt for the I-5 Killer".  The movie was based on the book "The I-5 Killer" by crime author Ann Rule.

Andrew Luster: Andrew Stuart Luster (born December 15, 1963) is the great-grandson of cosmetics giant Max Factor, Sr., and heir to the Max Factor cosmetics fortune.  In 2003 he was convicted of multiple sexual assaults using the date-rape drug GHB.

GHB receptor: The γ-hydroxybutyrate (GHB) receptor (GHBR), originally identified as GPR172A, is a G protein-coupled receptor (GPCR) that binds the neurotransmitter and psychoactive drug γ-hydroxybutyric acid (GHB).

Psychoactive drug: A psychoactive drug, psychopharmaceutical, or psychotropic is a chemical substance that changes brain function and results in alterations in perception, mood, consciousness or behavior.  These substances may be used medically; recreationally; to purposefully improve performance or alter one's consciousness; as entheogens; for ritual, spiritual, or shamanic purposes; or for research.  Some categories of psychoactive drugs, which have therapeutic value, are prescribed by physicians and other healthcare practitioners.  Examples include anesthetics, analgesics, anticonvulsant and antiparkinsonian drugs as well as medications used to treat neuropsychiatric disorders, such as antidepressants, anxiolytics, antipsychotics, and stimulant medications.  Some psychoactive substances may be used in the detoxification and rehabilitation programs for persons dependent on or addicted to other psychoactive drugs.

Supporting paragraphs: Andrew Luster Gamma-Hydroxybutyric acid
Answer: γ-Hydroxybutyric acid (GHB)