ABSTRACT
Anuran amphibians' ability to maintain their activity at high temperatures or low humidity depends on their capacity to face dehydration, especially when they display diurnal and terrestrial life habits. Melanophryniscus rubriventris is a diurnal and terrestrial toad from humid Yungas Andean forests that breeds in temporary ponds. It is exposed to the recurrent risk of dehydration because of pond desiccations during the breeding season. Here, we study how M. rubriventris males behaviorally respond to dehydration by measuring their voluntary activity under an ex-situ experiment. Toads with different hydration levels were exposed to a circular track for voluntary activity measurements. Dehydrated males of M. rubriventris toads did not adopt a water-conserving posture staying active during the test and increasing walking under severe dehydration. Certain tolerance to dehydration would allow performing daily activities under challenging diurnal conditions. The increased walking under severe dehydration suggests water or shelter-seeking behavior that would be crucial for diurnal and terrestrial toads to overcome the unpredictable hydric environment during the breeding season.
ABSTRACT
Context Coriandrum sativum L. (Apiaceae) (coriander) is an herb grown throughout the world as a culinary, medicinal or essential crop. In traditional medicine, it is used for the relief of anxiety and insomnia. Systemic hydro-alcoholic and aqueous extract from aerial parts and seeds had anxiolytic and sedative action in rodents, but little is known about its central effect in chicks. Objective To study the effects of intracerebroventricular administration of essential oil from coriander seeds and its major component linalool on locomotor activity and emotionality of neonatal chicks. Materials and methods The chemical composition of coriander essential oil was determined by a gas-chromatographic analysis (> 80% linalool). Behavioural effects of central administration of coriander oil and linalool (both at doses of 0.86, 8.6 and 86 µg/chick) versus saline and a sedative diazepam dose (17.5 µg/chick, standard drug) in an open field test for 10 min were observed. Results Doses of 8.6 and 86 µg from coriander oil and linalool significantly decreased (p < 0.05) squares crossed number, attempted escapes, defecation number and distress calls, and significantly increased (p < 0.05) the sleeping posture on an open field compared with saline and were similar to the diazepam group. Discussion and conclusion The results indicate that intracerebroventricular injection of essential oil from Coriandrum sativum seeds induced a sedative effect at 8.6 and 86 µg doses. This effect may be due to monoterpene linalool, which also induced a similar sedative effect, and, therefore, could be considered as a potential therapeutic agent similar to diazepam.