Does reduction of blood prolactin levels reveal the activation of central dopaminergic pathways conveying reward in top athletes?

Prolactin blood levels are modulated directly by CNS via the known tubero-infundibular dopaminergic neurons which exert an inhibitory action on lactotrope cells in the hypophysis. Prolactin is devoid of peripheral negative feedback and via lesser known central pathways (e.g., mesolimbic and mesocortical) might be further tuned by means of appropriate stimuli (e.g., addictive drugs, gambling, exercise and so forth). Therefore, a prolactin test can be utilised to obtain an objective index to assess the compliance to exercise in men. This index may be used to identify the most suitable athlete for a given sport and mainly to survey exercise as rewarding behaviour in trained people. Prolactin was assessed in male top world windsurfers (WS) and in a control group of non-windsurfer trained subjects (CS) during an exercise simulating marine windsurfing. The result was that prolactin levels decreased significantly in WS with respect to CS when compared with pre-test levels (WS: -22.7%; P<0.05).

Unchanging cardiac activity while increasing respiratory activity at the start of exercise in man: a beat-by-beat analysis by means of the impedance cardiography method.

Both respiratory and cardiodynamic parameters were analyzed (the latter non invasively by means of a computerized impedance cardiograph) in 6 subjects at the start of voluntary dorsal ankle flexions. Increased mean inspiratory flow with a slow reduction in end tidal PCO2 was shown in the breath following the start of movements, and these findings indicate the nervous origin of this hyperventilation. Within the same breath, left cardiac output, stroke volume and ventricular ejection time remained unchanged, and the same is true of heart rate and ventricular performance indexes depending on both the first derivative of the base thoracic electrical bioimpedance and on the mean left ventricle ejection flow, as well as in the systemic venous return index depending on the basal value of the thoracic impedance. These results, indicating that no cardiodynamic intervention in the neurogenic hyperventilation was seen, show that nervous stimuli elicited at the start of voluntary exercise may exert a direct action on respiratory control structures.

[Plasma lipoprotein levels in relation to dietary habits]. / Livello delle lipoproteine plasmatiche in rapporto alle abitudini alimentari.

We carried out a nutritional and haematological survey on 130 pupils of a boarding school in Cagliari in order to determine the relationship between plasma lipoprotein and nutritional habits, particularly, we determined beta/alpha ratio of lipoprotein comparing it with plasma values in hospitalized patients, suffering from metabolic and cardiovascular disease. The results allowed us to observe that 92% of hospitalized patients and 17% of subjects, presumably in good health, showed beta/alpha ratio greater than 2,5. The latter, apparently insignificant, is very important because it was detected in young subjects; as their diet was high-fat and high-carbohydrate, a nutritional and haematological survey will be always necessary in order to prevent illnesses.

[Dietary habits of apparently healthy boys and hospitalized adults]. / Le abitudini alimentari di ragazzi apparentemente sani e di adulti ospedalizzati.

We required into the nutritional habits of adolescents--presumably in good health--and of hospitalized adults. We observed that caloric excesses, through equally distributed in protides, carbohydrates and lipids, might be negative factors in young people who practise no sports; taking into account that their diet was similar to the diet of that patients suffering from metabolic and cardiovascular diseases, used to eat when they were young.