Mesa, J. | Search bioRxiv

bioRxiv2025

Embryonic and larval development of Atelopus cruciger (Lichtenstein and Martens, 1856) (Anura: Bufonidae)

Harlequin toads (Atelopus) are one of the amphibian groups in greatest need of urgent conservation measures, Atelopus cruciger is one of the few species with known stable populations, yet basic natural history, including the embryonic and larval stages, remains largely unknown. We describe for the first time the development of its tadpole, from egg to tail resorption. The tadpole of Atelopus cruciger is gastromyzophorous with a general morphology resembling that for other congeneric species but with a distinct W-shaped whitish band that spans transversely across the midline of its dorsum. Development from egg to tail resorption takes between 110-147 days. In the wild, tadpoles live camouflaged beneath and alongside rocks in shallow sections of fast-flowing streams, with clear soft waters.

zoology↗

bioRxiv2020

Role of prefrontal cortex projections to the nucleus accumbens core in mediating the effects of ceftriaxone on cued cocaine relapse

Ceftriaxone is an antibiotic that reliably attenuates the reinstatement of cocaine-seeking after extinction while preventing the nucleus accumbens (NA) core glutamate efflux that drives reinstatement. However, when rats undergo abstinence without extinction, ceftriaxone attenuates context-primed relapse but NA core glutamate efflux still increases. Here we sought to determine if the same would occur when relapse is prompted by both context and discrete cues (context+cues) after cocaine abstinence. Male rats self-administered intravenous cocaine for 2 hr/day for 2 weeks. Cocaine delivery was accompanied by drug-associated cues (light+tone). Rats were then placed into abstinence with daily handling but no extinction training for two weeks. Ceftriaxone (200 mg/kg IP) or vehicle was administered during the last 6 days of abstinence. During a context+cue relapse test, microdialysis procedures were conducted. Rats were perfused at the end of the test for later Fos analysis. A separate cohort of rats was infused with the retrograde tracer cholera toxin B in the NA core and underwent the same self-administration and relapse procedures. Ceftriaxone increased baseline glutamate and attenuated both context+cue-primed relapse and NA core glutamate efflux during this test. Ceftriaxone reduced Fos expression in regions sending projections to the NA core (prefrontal cortex, basolateral amygdala, ventral tegmental area) and specifically reduced Fos in prelimbic cortex and not infralimbic cortex neurons projecting to the NA core. Thus, when relapse is primed by drug-associated cues and context, ceftriaxone is able to attenuate relapse by preventing NA core glutamate efflux, likely through reducing activity in prelimbic NA core-projecting neurons.

neuroscience↗