Cardiorespiratory and Neuroprotective Effects of Caffeine in Neonate Animal Models

Caffeine is widely used to improve neonatal health in animals with low vitality. Due to its pharmacokinetics and pharmacodynamics, caffeine stimulates the cardiorespiratory system by antagonism of adenosine receptors and alteration in Ca+2 ion channel activity. Moreover, the availability of intracellular Ca+2 also has positive inotropic effects by increasing heart contractibility and by having a possible positive effect on neonate vitality. Nonetheless, since neonatal enzymatic and tissular systems are immature at birth, there is a controversy about whether caffeine is an effective therapy for newborns. This review aims to analyze the basic concepts of caffeine in neonatal animal models (rat and mouse pups, goat kids, lambs, and piglets), and it will discuss the neuroprotective effect and its physiological actions in reducing apnea in newborns.

Simultaneous Quantification of Caffeine and Its Main Metabolites by Gas Chromatography Mass Spectrometry in Horse Urine

Caffeine is one of the naturally occurring alkaloids and it is metabolized to paraxanthine, theophylline, and theobromine. The analyses of caffeine and its metabolites are challenging since the metabolites theophylline and paraxanthine generate similar product and precursor ions. In this study, a new method was developed for simultaneous analysis of caffeine, paraxanthine, theobromine and theophylline in horse urine using Gas chromatography-Mass Spectrometry (GC-MS). Urine samples were treated using solid phase extraction followed by the elution with dichloromethane/isopropanol (90/10) after pH was adjusted to 6, and then derivatization with MSTFA-1%TMCS before analysis by GC-MS. Sample preparation and derivatization steps were optimized and the method permitted elution all of these analytes within 13 min. The method was fully validated according to Commission Decision 2002/657/EC guidelines. The calibration curves were linear with a correlation coefficient of >0.99. Precision and accuracy were well within the 15% acceptance range and the method was robust. The validation results demonstrated that the method is highly reproducible, easily applicable and selective. The method was applied to urine samples collected from racehorses to demonstrate its applicability.

The use of caffeine as a respiratory stimulant in a cat

OBJECTIVE

To report the use of caffeine as a respiratory stimulant in a cat with hypoventilation.

CASE SUMMARY

A cat was mechanically ventilated due to persistent hypercapnia (P_et co₂  > 75 mm Hg) following median sternotomy and thymectomy. After 3 days of mechanical ventilatory support, the cat would initiate breaths but failed weaning due to persistent hypercapnia. Following administration of intravenous caffeine (total 12 mg/kg over 24 h), respiratory and mental status rapidly improved. The cat was subsequently extubated and able to maintain Pvco₂  < 50 mm Hg. The cat was later diagnosed with myasthenia gravis. Quality of life 13 months after discharge was reported as excellent by her owner.

NEW OR UNIQUE INFORMATION PROVIDED

Caffeine may be considered as a respiratory stimulant in cats with hypoventilation.

Intense Exercise and Aerobic Conditioning Associated with Chromium or L-Carnitine Supplementation Modified the Fecal Microbiota of Fillies

Recent studies performed in humans and rats have reported that exercise can alter the intestinal microbiota. Athletic horses perform intense exercise regularly, but studies characterizing horse microbiome during aerobic conditioning programs are still limited. Evidence has indicated that this microbial community is involved in the metabolic homeostasis of the host. Research on ergogenic substances using new sequencing technologies have been limited to the intestinal microbiota and there is a considerable demand for scientific studies that verify the effectiveness of these supplements in horses. L-carnitine and chromium are potentially ergogenic substances for athletic humans and horses since they are possibly able to modify the metabolism of carbohydrates and lipids. This study aimed to assess the impact of acute exercise and aerobic conditioning, associated either with L-carnitine or chromium supplementation, on the intestinal microbiota of fillies. Twelve “Mangalarga Marchador” fillies in the incipient fitness stage were distributed into four groups: control (no exercise), exercise, L-carnitine (10g/day) and chelated chromium (10mg/day). In order to investigate the impact of acute exercise or aerobic conditioning on fecal microbiota all fillies undergoing the conditioning program were analyzed as a separate treatment. The fillies underwent two incremental exercise tests before and after training on a treadmill for 42 days at 70–80% of the lactate threshold intensity. Fecal samples were obtained before and 48 h after acute exercise (incremental exercise test). Bacterial populations were characterized by sequencing the V4 region of the 16S rRNA gene using the MiSeq Illumina platform, and 5,224,389 sequences were obtained from 48 samples. The results showed that, overall, the two most abundant phyla were Firmicutes (50.22%) followed by Verrucomicrobia (15.13%). The taxa with the highest relative abundances were unclassified Clostridiales (17.06%) and "5 genus incertae sedis" from the phylum Verrucomicrobia (12.98%). There was a decrease in the phylum Chlamydiae and in the genus Mycobacterium after the second incremental exercise test. Intense exercise changed the community’s structure and aerobic conditioning was associated with changes in the composition and structure of the intestinal bacterial population of fillies. The intra-group comparison showed that chromium or L-carnitine induced moderate changes in the fecal microbiota of fillies, but the microbiota did not differ from the control group, which was exercised with no supplementation. Fecal pH correlated positively with Simpson’s index, while plasma pH correlated negatively. Our results show that exercise and aerobic conditioning can change in the microbiota and provide a basis for further studies enrolling a larger number of horses at different fitness levels to better understand the effects of exercise and training on the intestinal microbiota of horses.