Titi monkey neophobia and visual abilities allow for fast responses to novel stimuli

The Snake Detection Theory implicates constricting snakes in the origin of primates, and venomous snakes for differences between catarrhine and platyrrhine primate visual systems. Although many studies using different methods have found very rapid snake detection in catarrhines, including humans, to date no studies have examined how quickly platyrrhine primates can detect snakes. We therefore tested in captive coppery titi monkeys (Plecturocebus cupreus) the latency to detect a small portion of visible snake skin. Because titi monkeys are neophobic, we designed a crossover experiment to compare their latency to look and their duration of looking at a snake skin and synthetic feather of two lengths (2.5 cm and uncovered). To test our predictions that the latency to look would be shorter and the duration of looking would be longer for the snake skin, we used survival/event time models for latency to look and negative binomial mixed models for duration of looking. While titi monkeys looked more quickly and for longer at both the snake skin and feather compared to a control, they also looked more quickly and for longer at larger compared to smaller stimuli. This suggests titi monkeys’ neophobia may augment their visual abilities to help them avoid dangerous stimuli.

COMPARISONS OF THE HISTOLOGICAL MORPHOLOGY AND IN VITRO PERCUTANEOUS ABSORPTION OF CAFFEINE IN SHED SNAKE SKIN AND HUMAN SKIN

The employment of excised skin (human or animal) mounted in diffusion cells is frequently used for the characterization of biopharmaceutical properties of topical semisolids dosage forms. Reptile skin from snake appears to be a useful alternative to other animal and human skins in assessing the potential for transdermal drug delivery. The aim of the study was to compare human and snake skin from a histological point of view. Furthermore the absorption of caffeine, as a hydrophilic model substance, was compared on snake shed skins (two anatomical locations; ventral and dorsal), from three different species, Python regius, Epicrates maurus colombianus, Lampropeltis triangulum campbelli, and human skin. Snake skin shows histological similarity to human Stratum corneum in term of thickness and composition. Regarding the absorption, the cumulative amount of caffeine increased linearly with time through the dorsal and ventral shed skins of all 3 species. Except for Lampropeltis triangulum campbelli ventral skin, the caffeine permeation behavior obtained on all snake shed skins evaluated was in a similar range as on human skin. One main advantage of shed skin, is that snakes molt regularly and can provide many sheds, that can be obtained without sacrificing the animals.Key words: caffeine; transdermal; shed skin; in vitro; snake; topical formulation PRIMERJAVA HISTOLOŠKE ZGRADBE TER PERKUTANE ABSORPCIJE KOFEINA IN VITRO V LEVKU KAČ IN ČLOVEŠKI KOŽI Povzetek: Koža (človeškega ali živalskega izvora) se pogosto uporablja kot orodje za proučevanje biofarmacevtskih lastnosti topikalnih zdravil. Koža kač bi lahko bila uporabna alternativa drugim živalskim kožam in človeški koži pri oceni sposobnosti prenosa zdravil preko kože. Cilj študije je bil histološka primerjava človeške in kačje kože ter primerjava absorpcije kofeina kot hidrofilne modelne snovi na levkih kač iz dorzalnega in ventralnega področja treh različnih vrst kač: kraljevega pitona (Python regius), mavričnega udava (Epicrates maurus colombianus), mlečne kače (Lampropeltis triangulum campbelli). Kačja koža je histološko podobna človeški glede debeline in sestave roženi plasti (stratum corneum). Glavna prednost levitve kač je, da se dogaja večkrat, kar omogoča pridobitev več levkov, ki se jih lahko pridobi brez žrtvovanja živali. Rezultati so pokazali, da se je skupna količina kofeina sčasoma linearno povečevala v dorzalnih in ventralnih levkih pri vseh treh vrstah kač, razen na na ventralnem področju levka mlečne kače (Lampropeltis triangulum campbelli), pri katerem je bila prehodnost kofeina podobna kot pri prehodu skozi človeško kožo. Ključne besede: kofein; transdermalno; levek; in vitro; kača; topikalni pripravek