The effect of phenothiazine on plasma prolactin levels in non-pregnant mares.

This research paper studied the effect of perphenazine and phenothiazine on the plasma prolactin levels in non-pregnant pony mares and found that perphenazine increased plasma prolactin concentrations, while phenothiazine had no effect.

Study Design

The researchers recruited sixteen non-pregnant pony mares and grouped them into four clusters based on their age and body weights. The groups were randomly assigned one of four treatments. These treatments consisted of:

• Oral administration of perphenazine at 0.5 mg/kg body weight
• Oral administration of perphenazine at 1.0 mg/kg body weight
• Oral administration of phenothiazine at 10 mg/kg body weight
• A control group that likely received no treatment

Blood samples were collected from these mares for the measurement of plasma prolactin levels.

Methodology

Blood samples were taken by way of jugular venepuncture, and the plasma prolactin concentrations were measured using an homologous assay for equine prolactin. The researchers made use of a statistical technique known as variance analysis for the data which was arranged in a split plot over time format.

Findings

The findinds of the study showed that perphenazine, when given orally at the doses of 0.5 and 1.0 mg/kg body weight, led to an increase in the plasma prolactin concentrations. However, significant increases were noticed only 3 and 6 hours after feeding. By the 11th hour post-drug administration, prolactin concentrations had returned to normal levels.

Side Effects

The higher dose of perphenazine (1.0 mg/kg body weight) was discontinued after two days due to two mares exhibiting signs of hyperesthesia, a condition marked by an increased sensitivity to sensory stimuli, such as touch or pain. This shows that there might be severe side effects involved with the use of perphenazine, even though it proved effective in increasing prolactin levels.

No Effect of Phenothiazine

Interestingly, the study found no noticeable change in plasma prolactin concentrations following the oral administration of phenothiazine at 10 mg/kg body weight. This implies that phenothiazine doesn’t bring about a change in prolactin levels in non-pregnant pony mares, at least at the dosage used in this study.