Pubertal delay in male nonhuman primates (Macaca mulatta) treated with methylphenidate.

Juvenile male rhesus monkeys treated with methylphenidate hydrochloride (MPH) to evaluate genetic and behavioral toxicity were observed after 14 mo of treatment to have delayed pubertal progression with impaired testicular descent and reduced testicular volume. Further evaluation of animals dosed orally twice a day with (i) 0.5 mL/kg of vehicle (n = 10), (ii) 0.15 mg/kg of MPH increased to 2.5 mg/kg (low dose, n = 10), or (iii) 1.5 mg/kg of MPH increased to 12.5 mg/kg (high dose, n = 10) for a total of 40 mo revealed that testicular volume was significantly reduced (P < 0.05) at months 15 to 19 and month 27. Testicular descent was significantly delayed (P < 0.05) in the high-dose group. Significantly lower serum testosterone levels were detected in both the low- (P = 0.0017) and high-dose (P = 0.0011) animals through month 33 of treatment. Although serum inhibin B levels were increased overall in low-dose animals (P = 0.0328), differences between groups disappeared by the end of the study. Our findings indicate that MPH administration, beginning before puberty, and which produced clinically relevant blood levels of the drug, impaired pubertal testicular development until ∼5 y of age. It was not possible to resolve whether MPH delayed the initiation of the onset of puberty or reduced the early tempo of the developmental process. Regardless, deficits in testicular volume and hormone secretion disappeared over the 40-mo observation period, suggesting that the impact of MPH on puberty is not permanent.

Nocturnal penile tumescence and rigidity testing in bicycling patrol officers.

A health assessment study was conducted in response to complaints of groin numbness in a bicycling police unit. Seventeen male cyclists were compared with 5 nonbiking men. The cyclists rode an average of 5.4 hours per day, and 91% indicated they experienced groin numbness on occasion. Each man wore the RigiScan Plus Rigidity Assessment System for one normal sleep session. Pressure measurements were also taken between the cyclist and the bicycle saddle. The percentage of sleep sessions that recorded an erectile event was significantly lower in the cyclists than it was in noncyclists (cyclists 27.1%; noncyclists 42.8%; P =.008). This duration percentage is negatively correlated with average hours a day that cyclists rode their bikes (r = -.41; P =.05), the number of days a week they rode (r = -.55; P =.009), and the average pressure exerted on the nose of the bike saddle (r = -.39; P =.08). The other measures of erectile quality (tumescence activity units [TAUs] and rigidity activity units [RAUs] of both the base and tip of the penis) were lower in the cyclists, but did not reach statistical significance. The number of hours cyclists rode during the day of RigiScan Plus assessment was negatively correlated with penis tip RAU (r = -.41; P =.04), and tip TAU (r = -.45; P =.04). These data suggest that prolonged bicycle riding may have negative effects on nocturnal erectile function and indicate a need for innovative bicycle saddle designs.

Sperm storage in turtles: A male perspective.

The storage and behavior of sperm collected from the epididymis of two emyiid turtles were examined. In Chrysemys picta, the weight of the epididymis does not change significantly throughout the year as does the testis. However, in this species, as well as in Trachemys scripta, the epididymis contains sperm throughout the entire year. Sperm from both species have a relatively low motility and velocity of movement. In C. picta, equally low motilities are observed both in the autumn, shortly after spermiation, and in spring. Motility could be augmented by the addition of isobutyl methyl xanthine (IBMX, 0.5 mmol l(-1)). Epididymal sperm remained viable in excess of 40 days in vitro when stored in F-10 buffer, during which time motility and swimming velocity could be augmented with IBMX. The longevity and low motility of turtle sperm facilitates its storage by either males or females, and creates conditions that promote the wide dissemination, over time, of gametes produced in a narrow time window.