Hydralazine-treated rabbits ate less, weighed less, and had less bodyfat

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Friday, June 11, 2004 12:20 pm Email this article
Rabbits given the antihypertensive drug hydralazine ate less, weighed less, and had a lower percent bodyfat according to a study from researchers at the University of North Texas Health in Fort Worth.

“[H]ydralazine had profound effects on body composition,” the authors of the study concluded.

HYDRALAZINE-TREATED RABBITS ATE 13% LESS

Obese rabbits treated with hydralazine ate 13 percent less food than control rabbits.

The obese rabbits were fed a high-fat diet and allowed to eat as much as they wanted.

HYDRALAZINE-TREATED RABBITS WEIGHED 8% LESS

Hydralazine-treated obese rabbits weighed 8 percent less than controls.

Hydralazine did not affect the bodyweight of lean rabbits that were kept on a maintenance diet.

HYDRALAZINE-TREATED RABBITS HAD 5% PERCENT BODYFAT

Obese animals given hydralazine had roughly 5 percent lower bodyfat than obese animals in the control group that weighed the same: 23 percent bodyfat versus 28 percent. (This data was approximated from figure 1 on page 186.)

Lean animals given hydralazine and kept on a maintenance diet also had roughly 5 percent lower bodyfat than lean controls: 8 percent bodyfat versus 13 percent. (This data was approximated from figure 1 on page 186.)

Note: The abstract states that percent bodyfat in hydralazine-treated animals was 15.7 percent compared to 21.8 percent in controls, however, this is an average of all animals, both lean and obese, and not a comparison of lean animals of the same weight and obese animals of the same weight. Comparing treated and untreated animals of the same weight reveals the effect of the drug better than animals of different weights.

HYDRALAZINE-TREATED RABBITS HAD 4% HIGHER PERCENT WATER CONTENT

Percent body water was 4.4 percent greater in hydralazine-treated obese rabbits than control: 59.8 percent water for hydralazine-treated rabbits versus 55.4 percent for controls.

NAUSEA PROBABLY NOT RESPONSIBLE FOR HYDRALAZINE’S EFFECT ON APPETITE

Nausea, a possible side effect of hydralazine, might have been responsible for the decrease in food consumption eaten by hydralazine-treated animals, the authors suggested. However, this does not seem to be the case since hydralazine-treated animals that weighed the same as controls, still had less bodyfat.

HYDRALAZINE MIGHT STIMULATE RELEASE OF ADRENALINE AND NORADRENLINE

Hydralazine’s effect on appetite and bodyfat might be due to a stimulation of the sympathetic nervous system, an increase in adrenaline and noradrenaline, however, they only took a single measurement in this study, and did not find levels to be elevated. Another study, however, found hydralazine increase daily output of adrenaline and noradrenaline levels in fructose-fed rats.

THIS WAS NOT AN OBESITY STUDY

The purpose of this study was not to test hydralazine as a possible treatment for obesity.

This study was conducted because hydralazine is often used as a control drug in animal studies to compare with other antihypertensive medication, and the assumption has been that hydralazine has no other effect on the body except to lower blood pressure, which turns out is not correct.

NO MENTION OF HYDRALAZINE AS OBESITY TREATMENT

The authors of this study do not discuss the possibility of using hydralazine as a treatment for obesity.

DOSES USED SOMEWHAT LARGER THAN THOSE RECOMMENDED FOR HUMANS

The doses in this study of rabbits were 2.7 mg per pound of body weight for lean animals, and 4.5 to 6.4 mg per pound of body weight for obese animals. this would be the equivalent of 270 mg in a 200 pound human.

Doses used in humans for the control of blood pressure are “40 to 200 milligrams (mg) per day divided into two or four doses” according to MedlinePlus.

Hydralazine lowers blood pressure by dilating blood vessels.

In humans, hydralazine is often combined with beta-blockers and diuretics to minimize side effects such as tachycardia (elevated heart rate), edema (swelling due to fluid accumulation) and nausea.

LOSS OF APPETITE IS A KNOWN SIDE EFFECT OF THE DRUG

MedlinePlus states that loss of appetite, nausea or vomiting are some of the possible side effects of the drug.

REFERENCE

Carroll J, King J, Cohen J. Hydralazine treatment alters body composition in the rabbit model of obesity. Acta Physiol Scand. 2004 Jun, 181(2):183-91.

AUTHOR CORRESPONDENCE:

J. F. Carroll
Department of Integrative Physiology
University of North Texas Health Science Center
3500 Camp Bowie Blvd
Fort Worth, TX 76107-2699 USA

Articles on the same subject can be found here:

• Blood Pressure

• Body Composition

• Hydralazine