Suppression of Serum Prolactin Levels after Sports Concussion with Prompt Resolution Upon Independent Clinical Assessment To Permit Return-to-Play

Abstract

A significant outflow of neurotransmitters and metabolites with associated enhanced cortical excitation occurs after concussive head trauma. Cellular changes in the acute post-injury period cannot be observed directly in humans, and as such, require indirect evidence from systems sufficiently sensitive to central neuronal cellular excitation. Dopamine is a neurotransmitter with numerous targets in the central and peripheral nervous system. Changes to central dopaminergic tone result in reciprocal responses to the level of serum prolactin (PRL). Thus, a concussion may lead to abnormal dopaminergic tone, resulting in dynamic perturbations in the serum PRL concentration. To determine the effect of concussion on serum PRL concentrations, venipuncture was performed in the morning in four male intercollegiate athletes (age, 20 ± 1 years; height, 71 ± 5 inches; weight, 174 ± 21 pounds) within 48 h of concussion and again at 7 and 14 days post-injury. Serum PRL concentrations for each visit were categorized by quartile within the normal range. In all athletes, serum PRL concentrations increased from the lower quartiles in samples obtained closer to the time of injury to the higher quartiles at 14 days post-injury. These serum PRL changes accompanied the resolution of symptoms and the clinical decision to permit return-to-play. It may be postulated that transient augmentation of central dopaminergic tone resulted in inhibition of PRL secretion early after concussion and that disinhibition of PRL release occurred when central dopaminergic tone subsequently returned to baseline levels. This novel observation provides evidence for dopaminergic dysfunction after concussion that may be tracked by determination of serum PRL levels.

Analysis of serum cortisol to predict recovery in paediatric sport-related concussion

“…Previous studies have examined the neurometabolic response to SRC. These studies have examined alterations in tau protein, 4,5 s100B protein, [5][6][7] neuron specific enolase (NSE), 5,6 AMPAR peptide, 8 glial fibrillary acidic protein (GFAP), 9 prolactin levels, 10 plasma soluble prion protein (PrPC), 9 metabolites, 11 saliva cortisol 12 and metabolic markers of depression in an attempt to develop more accurate diagnostic and prognostic methods for concussion. 11 Interestingly, Hutchison et al looked at changes in acute saliva cortisol levels post SRC.…”

“…Further, two studies have examined acute pituitary changes following adult SRC. La Fountaine et al reported acute prolactin was significantly decreased in collegiate football players with SRC and gradual increase in prolactin mirrored recovery 10. Prolactin is released by the anterior pituitary and an acute decline in prolactin may reflect direct damage to the HPA following SRC.…”

Role of advanced neuroimaging, fluid biomarkers and genetic testing in the assessment of sport-related concussion: a systematic review

“…In contrast, NSE,72 visinin-like protein-1,74 total tau,41 74 81 tau-A79 and salivary cortisol82 did not distinguish concussed athletes from non-concussed athletes. Several serum biomarkers such as SNTF,78 quinolinic acid,83 prolactin84 and tau-A79 showed early evidence in predicting outcomes following sport concussion. Finally, decreased levels of amyloid-beta-42 and increased neurofilament light in CSF were observed in athletes with postconcussion syndrome, although these results were largely driven by athletes with postconcussion syndrome duration of more than 1 year 81…”

Preliminary Evidence for a Window of Increased Vulnerability to Sustain a Concussion in Females: A Brief Report

“…Specifically, the hypothesis stated that a “…TBI occurring in the setting of high progesterone results in a sudden decrease of progesterone.” The basis for the decline in progesterone among their luteal phase injury participants was not specified, nor was a blood concentration obtained to verify it. However, secondary hypopituitarism has been shown to emerge following MTBI across a wide range of clinical presentations (31–37). In their study cohort, nearly twice as many females who met the inclusion criterion sustained the MTBI during the follicular phase than in the luteal phase, and women taking hormone contraceptives were separated into their own group without consideration for the phase of the cycle that they were in (e.g., where they were in the pill pack), if they had a monthly menstruation or were suppressing menstruation altogether.…”