Gonadotropin-releasing hormone (GnRH) is the central regulator of the hypothalamic-pituitary-gonadal axis. Steroid hormones synthesized and released by the gonads, such as androgens, negatively feedback to the hypothalamus to regulate GnRH synthesis and secretion, and precise regulation is vital for proper reproductive function. In vitro experiments, utilizing the GnRH immortalized neuronal cell line, GT1-7, were performed to elucidate the mechanisms by which androgen receptor (AR) disrupts GnRH transcription. We show that methyltrienolone (R1881), an AR agonist, represses GnRH expression through the proximal promoter (GnRHp) as well as the distal enhancer (GnRHe) and causes increased AR interaction with those regions. Classical gene regulation by AR involves binding to androgen responsive elements (AREs). However, GnRHp and GnRHe do not contain putative AREs. Thus, repression may be occurring via AR interaction with DNA-bound transcription factors or with co-factors. We find that multiple regions, including the -91/-86 region in GnRHp, are required for AR-mediated repression rather than a single transcription factor-binding site. On the other hand, repression of GnRHe maps to the -1800/-1766 region and may require nucleotides -1789/-1787. AR and thyroid transcription factor-1 (TTF-1 or Nkx2.1) may be part of unknown protein complexes binding to the -1795/-1790 and - 1792/-1784 regions of GnRHe, respectively. Interestingly, we also find that R1881 suppresses the activity of Rous sarcoma virus promoter (RSVp) when three copies of the Nkx2.1 consensus binding sequence are positioned directly upstream of RSVp. In conclusion, AR activation by R1881 represses GnRH expression by utilizing multiple sites throughout GnRHp, the 1800/-1766 region of GnRHe, and possibly involves Nkx2.1

We previously identified FOXL2 as a critical component in FSHβ gene transcription. Here, we show that mice deficient in FOXL2 have lower levels of gonadotropin gene expression and fewer LH- and FSH-containing cells, but the same level of other pituitary hormones compared to wild-type littermates, highlighting a role of FOXL2 in the pituitary gonadotrope. Further, we investigate the function of FOXL2 in the gonadotrope cell and determine which domains of the FOXL2 protein are necessary for induction of FSHβ transcription. There is a stronger induction of FSHβ reporter transcription by truncated FOXL2 proteins, but no induction with the mutant lacking the forkhead domain. Specifically, FOXL2 plays a role in activin induction of FSHβ, functioning in concert with activin-induced SMAD proteins. Activin acts through multiple promoter elements to induce FSHβ expression, some of which bind FOXL2. Each of these FOXL2-binding sites is either juxtaposed or overlapping with a SMAD-binding element. We determined that FOXL2 and SMAD4 proteins form a higher order complex on the most proximal FOXL2 site. Surprisingly, two other sites important for activin induction bind neither SMADs nor FOXL2, suggesting additional factors at work. Furthermore, we show that FOXL2 plays a role in synergistic induction of FSHβ by GnRH and activin through interactions with the cJUN component of the AP1 complex that is necessary for GnRH responsiveness. Collectively, our results demonstrate the necessity of FOXL2 for proper FSH production in mice and implicate FOXL2 in integration of transcription factors at the level of the FSHβ promoter.

Background

The potential for impaired driving due to medication use can occur at any age, though older adults are more likely to take multiple prescribed medications and experience side effects that may affect driving ability. The purpose of this study was to characterize the relationship between medications and driving safety behaviors.

Methods

Data for this study came from the five-site Longitudinal Research on Aging Drivers (LongROAD) project. Participants were active drivers, age 65-79 years at enrollment, and patients at one of the 5 participating sites. Medication names and doses were obtained at baseline based on the "brown-bag review" method. Medications were coded using the American Hospital Formulary Service system. Driving data were collected by a GPS accelerometer installed in the study participants' main vehicles.

Results

Medication data were available for 2949 (98.6%) of the 2990 participants, and 2898 (96.9% of all participants) had both medication data and at least 30 recorded days of driving. The median number of medications taken per study participant was seven, with a range of 0-51. Total number of medications was significantly associated with a higher rapid deceleration rate. Certain medication classes were significantly associated with other driving outcomes, including central nervous system agents (more speeding events), hormones and gastrointestinal medications (more rapid decelerations), electrolytes (fewer rapid decelerations), and antihistamines (greater right to left turn ratio).

Conclusions

Older adult drivers are taking large quantities of prescription and non-prescription medications that may affect their driving safety. Certain medication classes are associated with potentially adverse driving patterns, such as speeding and rapid decelerations, while others are associated with potentially protective maneuvers, such as right hand turning. Further research is warranted to identify and mitigate potential adverse effects of such medications on driving safety in older adults.