Effects of Vasopressin on Blood‐Brain Transfer of Methionine in Dogs

Abstract

We used a simplified probe detection system for positron-emitting radionuclides in order to measure blood-brain barrier transport of amino acids in anesthetized dogs. Plasma and brain time-activity curves were recorded after intravenous bolus injection of L-[11C]methionine before and after administration of 1 microgram of vasopressin. Three-compartment models with three or four transfer coefficients were used to derive the kinetics of L-[11C]methionine uptake in brain. The blood-brain clearance of the tracer (K1) was 0.075 ml ml-1 min-1 before and 0.041 ml ml-1 min-1 after injection of vasopressin. The partition volume and the initial distribution (plasma) volume of methionine were unchanged and within the expected limits. The net accumulation rate of methionine (K), estimated by both the four-parameter (kinetic) and three-parameter (graphic) approaches, decreased after vasopressin injection in all six studies.

Developmental exposure to vasopressin increases aggression in adult prairie voles

“…Although the AVP antagonist used in the aforementioned studies was administered directly into the intracerebral ventricles of adult animals, it was assumed in our study that peripheral injections of 0.05 ng of AVP antagonist would be suitable given the size of the neonates (1͞10 of adult size) and their altricial state. It is known that the blood-brain barrier in altricial species is not fully formed at birth (22) and there is mounting physiological and behavioral evidence (23)(24)(25)(26)(27)(28)(29)(30) to suggest that AVP can pass and perhaps play a facilitatory role in the blood-brain barrier of neonatal and adult rats, respectively (31)(32)(33)(34). In our study, all of the pharmacological agents were injected intraperitoneally once per day by using a 30-gauge, 0.5-inch hypodermic needle affixed to a 100-l Hamilton syringe.…”

Developmental Exposure to Vasopressin Increases Aggression in Adult Prairie Voles

“…Although the AVP antagonist used in the aforementioned studies was administered directly into the intracerebral ventricles of adult animals, it was assumed in our study that peripheral injections of 0.05 ng of AVP antagonist would be suitable given the size of the neonates (1͞10 of adult size) and their altricial state. It is known that the blood-brain barrier in altricial species is not fully formed at birth (22) and there is mounting physiological and behavioral evidence (23)(24)(25)(26)(27)(28)(29)(30) to suggest that AVP can pass and perhaps play a facilitatory role in the blood-brain barrier of neonatal and adult rats, respectively (31)(32)(33)(34). In our study, all of the pharmacological agents were injected intraperitoneally once per day by using a 30-gauge, 0.5-inch hypodermic needle affixed to a 100-l Hamilton syringe.…”

Development of 18F-labeled radiotracers for neuroreceptor imaging with positron emission tomography

“…Preclinical PET studies in animals are suitable for this purpose [7, 8] and hence permit appropriate radiotracer evaluation. Initially, the PET scanner´s resolution was rather low (~10 mm) [238] allowing successful quantitation only in the brains of larger animals such as primates [239,240] , dogs [241][242][243] , cats [244,245] , and pigs [246][247][248] .…”

“…Preclinical PET studies in animals are suitable for this purpose [7, 8] and hence permit appropriate radiotracer evaluation. Initially, the PET scanner´s resolution was rather low (~10 mm) [238] allowing successful quantitation only in the brains of larger animals such as primates [239,240] , dogs [241][242][243] , cats [244,245] , and pigs [246][247][248] .During the last decade, various dedicated PET cameras for imaging in small animals have been developed, providing a resolution of 1-2 mm [6,249] .Moreover, the first PET/MRI systems have become available for both human and small-animal imaging, allowing more accurate identification of brain regions [250] .Thus, accurate quantitation is possible and similar to that achievable with autoradiography [7] . In addition, pharmacokinetic, multiple-tracer, and longitudinal studies can be performed in single subjects constituting a great potential for basic neuroscience research [251] , neuropharmacology [8,252] , and the investigation of animal models of neurological and neuropsychiatric disorders [7] .…”