Mydriasis model in rats as a simple system to evaluate α2-adrenergic activity of the imidazol(in)e compounds

How Does Usage of Serotonin Noradrenaline Reuptake Inhibitors Affect Intraocular Pressure in Depression Patients?

PURPOSE

To evaluate anterior segment parameters and intraocular pressure (IOP) modifications in patients using serotonin noradrenaline reuptake inhibitors (SNRIs) due to major depressive disorder.

METHODS

This cross-sectional study included 170 eyes of 85 subjects. All subjects were divided into three groups: group 1 included 44 healthy control subjects, group 2 included 22 patients receiving antidepressants for 1 week to 6 months, and group 3 included 19 patients receiving antidepressants for >6 months. All subjects underwent a detailed ophthalmologic examination, including gonioscopy. Anterior segments of all subjects were evaluated with the Scheimpflug system and pupil diameter (PD), central corneal thickness, anterior chamber depth (ACD), anterior chamber volume, and anterior chamber angle (ACA) measurements were enrolled.

RESULTS

The median IOP was significantly lower in patients using antidepressants [16.0 (11.0-21.0) mmHg] than the control group [17.5 (12.0-21.0) mmHg] (P = 0.041). The PD was significantly larger in patients using antidepressants [3.56 (2.29-5.60) mm] than the control group [2.95 (2.00-4.40) mm] (P = 0.000). In the study group, PD was also significantly larger in patients using SNRIs for ≥6 months [3.67 (2.38-5.08) mm] than <6 months [3.31 (2.29-5.60) mm] (P = 0.000). The median ACD was significantly lower in patients using antidepressants for ≥6 months [3.21 (2.52-4.06) mm] than the control group [3.44 (2.63-4.29) mm] (P = 0.000). ACAs were measured between 25° and 55° by Scheimpflug imaging.

CONCLUSIONS

Treatment of SNRIs causes mydriasis and decrease in width of ACD. These changes may not increase IOP as long as the patient has an open angle. SNRIs lead to decrease in IOP particularly in long-term usage.

Are Alpha-2D Adrenoceptor Subtypes Involved in Rat Mydriasis Evoked by New Imidazoline Derivatives: Marsanidine and 7-Methylmarsanidine?

The imidazoline compounds may produce mydriasis after systemic administration to some species (rats, cats, and mice). In mydriatic activity of imidazolines, α_2D-adrenoceptors subtype(s) seems to be involved. In this study, the pupil dilatory effect evoked by 2 newly synthesized imidazoline derivatives—α₂-adrenoceptor agonists: marsanidine and 7-methylmarsanidine—was compared. The compounds were tested alone as well as in the presence of α₂-adrenoceptor antagonists (nonselective, yohimbine, and selective toward the following α₂-adrenoceptor subtypes—α_2A-2-[(4,5-dihydro-1H-imidazol-2-yl)methyl]-2,3-dihydro-1-methyl-1H-isoindole maleate (BRL44408), α_2B-2-[2-(4-(2-methoxyphenyl)piperazin-1-yl)ethyl]-4,4-dimethyl-1,3-(2H,4H)-isoquinolindione dihydrochloride (ARC239), α_2C-JP1302, α_2D-2-(2,3-dihydro-2-methoxy-1,4-benzodioxin-2-yl)-4,5-dihydro-1H-imidazole hydrochloride [RX821002]). The agonists were studied in male Wistar rats and were administered intravenously in cumulative doses. The antagonistic compounds were given in a single dose before the experiment with marsanidine or 7-methylmarsanidine. Pupil diameter was measured with stereoscopic microscope equipped in green light filter. Marsanidine and 7-methylmarsanidine exerted marked mydriatic effects. BRL44408, JP1302, and ARC239 did not cause significant parallel shift to the right of the dose–effect curves obtained for both imidazolines. In case of yohimbine and RX821002, the marked parallel shifts of dose–response curves were observed, with the antagonistic effects of RX821002 more pronounced. In vivo pharmacodynamics experiment suggests that α_2D-adrenoceptor subtype is mainly engaged in mydriatic effects evoked in rats by imidazoline derivatives, in particular by clonidine.

NO system dependence of atropine-induced mydriasis and L-NAME- and L-arginine-induced miosis: Reversal by the pentadecapeptide BPC 157 in rats and guinea pigs

We revealed an immediate and hours-lasting particular NO-specific parallel miotic effect of L-NAME and L-arginine in rats and guinea pigs and a stable gastric pentadecapeptide BPC 157 157-particular effect vs. that of atropine-induced mydriasis while examining the NO system role in the normal pupils responses and pupils with atropine-induced mydriasis. We also assessed the responses to BPC 157 and its possible modulation of the changes caused by L-NAME/L-arginine and atropine. We administered locally (two drops/eye) or systemically (intraperitoneally/kg) [BPC 157 (0.4µg/eye; 10µg, 10ng, 10pg/kg), L-NAME (0.1mg/eye; 5mg/kg), and L-arginine (2mg/eye; 100mg/kg) alone and combined] at 3min prior to assessment (normal pupils) or alternatively at maximal 1% atropine-induced mydriasis (30min after two drops were administered to each eye). L-NAME/L-arginine. Normal pupil. L-NAME-miosis and L-arginine-miosis shortened and attenuated each other's responses when combined (L-NAME+L-arginine) (except with guinea pigs treated locally) and were thereby NO-specific. Atropine-pupil. Both L-NAME and L-arginine counteracted atropine-induced mydriasis. With few exceptions, the atropine+L-NAME+L-arginine-animals showed a consistent shift toward the left. BPC 157. Normal pupil. Always, BPC 157 alone (both species; locally; systemically; all regimens) did not affect normal pupils. Despite specific exceptions, BPC 157 distinctively affects L-arginine-miosis (prolongation) and L-NAME-miosis (shortening). When L-arginine and L-NAME were combined (L-NAME+L-arginine+BPC 157), the effect was less pronounced. Atropine-pupil. BPC 157 alone counteracted atropine-induced mydriasis. With few exceptions (when administered with L-NAME or L-arginine or L-NAME+L-arginine), BPC 157 augments their counteracting effects. Thus, along with its l-NAME/L-arginine effects, BPC 157 participates in ocular control, potentially via NO-mediated and cholinergic mechanisms.