Effects of slow infusions of KCl into the 3rd brain ventricle

Intraruminal fluid administration to goats: effects of handling and fluid temperature

Physiological stress response to intraruminal fluid administration was studied in 5 female goats. The fluid was given through a stomach tube. The water was cold (10 degrees C) or warm (38 degrees C) and in an amount of 7.5-10% of body weight. Plasma concentrations of adrenaline, noradrenaline and cortisol increased significantly after both treatments. Adrenaline and noradrenaline responses were greater and more longlasting after cold water administration, but there was no difference in cortisol response between cold and warm water. Haematocrit and plasma protein concentrations increased also and the effects of cold water lasted longer. Blood pressure showed a sharp rise of short duration and was independent of water temperature. The immediate tachycardiac response was similar with both treatments, but cold water caused an additional peak 15 min later. The cooling did not increase plasma histamine level. The results suggest that stomach intubation and administration of water into the rumen leads to strong activation of hormonal and cardiovascular stress parameters even in goats well adapted to handling. Low temperature of the fluid further heightens the effect. Warming of fluids to near body temperature before their administration is thus recommended.

Dipsogenic and feeding influences of intraventricularly infused anionic choline solutions

Chloride and bicarbonate solutions of choline were infused into the anteroventral part of the third ventricle of two different groups of rats through chronically implanted stainless steel cannulae. Dipsogenic and feeding responses elicited by these solutions were studied by observations taken at half hour intervals up to two h and then, after 24 h of infusions. Results were compared with the control response evoked by similar infusion of artificial cerebrospinal fluid (aCSF). Food and water intakes were recorded in different groups (n = 18 each) of rats. Dipsogenic response elicited by choline chloride solution in the observation taken 24 h after infusion, however, was higher only as compared to the control. Dipsogenic effect of bicarbonate solution was not significantly different from the control in the first two observations (30 and 60 min), but in the later observations (90, 120 min and 24 h), it was significantly higher. None of the choline solutions significantly alter feeding response within 2 h of infusions. However, in the observation taken 24 h after infusion, the response evoked by choline chloride was greater than that elicited by aCSF. The results support our earlier observation that chloride concentration of third ventricular CSF significantly influences water and food consumption. Intraventricularly administered choline also appears to have positive influence on these behaviors.

Influence of intracerebroventricularly infused anions on feeding response

Chloride and bicarbonate solutions of potassium, calcium, sodium, and barium were infused into the third ventricle of the rats to observe the influence of anions on feeding response. Stainless steel cannulae were chronically implanted into the anteroventral part of the third ventricle of 54 rats, which were divided in 9 equal groups. While the control group was given 10 microliters of artificial cerebrospinal fluid intraventricularly, the remaining 8 groups received the equal quantity (10 microliters) of one of the hypertonic equimolar test solutions. Chloride solutions of potassium, calcium, and barium evoked significantly (p less than 0.05) higher feeding than the control group, while none of the bicarbonate solutions influenced feeding significantly. Chloride solutions of all the 4 cations elicited significantly (p less than 0.05) higher feeding than the corresponding bicarbonate solutions in 24 hr. It was observed that though the cations differed, there was no significant difference in the responses elicited by the different chloride solutions. Similarly, various bicarbonate solutions elicited similar responses. Osmolality and pH of the infusion solution have not influenced feeding significantly. It is concluded that the anionic, but not the cationic concentration of the fluid bathing juxtacerebroventricular sensors, predominantly influence the feeding response.