Effects of photoperiod on hamster pineal melatonin concentrations

Morphometric analysis of the pineal complex of the golden hamster over a 24‐hour light: Dark cycle: I. The superficial pineal in untreated and optically enucleated animals

“…The rhythm in nuclear volume found in this study was similar to the pattern of melatonin production in golden hamsters maintained on a 14:lO 1ight:dark cycle, with peak values toward the end of the scotophase (dark period) (Panke et al, 1980). Our findings of circadian variation in nuclear volume are not, however, in agreement with earlier reports.…”

“…Since protein synthesis increases prior to melatonin production (Morrissey and Lovenberg, 1978), the peak values for the rough endoplasmic reticulum may reflect enhanced protein synthesis during the dark phase, possibly as a result of greater enzyme production. Alternatively, the biphasic rhythm in smooth endoplasmic reticulum is similar to the pattern of indole production by golden hamster pinealocytes, with nadirs occurring at the 1ight:dark interfaces (Panke et al, 1980;Steinlechner et al, 1983). Rhythms in the volume density of the Golgi complex and number of dense-cored vesicles displayed similar patterns.…”

Morphometric analysis of the pineal complex of the golden hamster over a 24‐hour light: Dark cycle: I. The superficial pineal in untreated and optically enucleated animals

“…The rhythm in nuclear volume found in this study was similar to the pattern of melatonin production in golden hamsters maintained on a 14:lO 1ight:dark cycle, with peak values toward the end of the scotophase (dark period) (Panke et al, 1980). Our findings of circadian variation in nuclear volume are not, however, in agreement with earlier reports.…”

“…Since protein synthesis increases prior to melatonin production (Morrissey and Lovenberg, 1978), the peak values for the rough endoplasmic reticulum may reflect enhanced protein synthesis during the dark phase, possibly as a result of greater enzyme production. Alternatively, the biphasic rhythm in smooth endoplasmic reticulum is similar to the pattern of indole production by golden hamster pinealocytes, with nadirs occurring at the 1ight:dark interfaces (Panke et al, 1980;Steinlechner et al, 1983). Rhythms in the volume density of the Golgi complex and number of dense-cored vesicles displayed similar patterns.…”

Daily and seasonal rhythmicity in the methylation of pineal indolic compounds in adult male golden hamsters, kept under natural conditions

“…7). Panke et aL (1978Panke et aL ( , 1979Panke et aL ( , 1980, Tamarkin et aL (1979), Rollag et aL (1980), and Brainard et al (1982 b), measuring aMT concentration, found higher concentrations of aMT only during the dark showing a peak at the end of the dark period. This difference might be explained by the use of different experimental approaches (see .…”

Rhythmic synthesis of various 5-methoxyindoles in the pineal gland of male adult golden hamsters, kept under the same artificial conditions throughout the year

“…The same result was obtained in hamsters by Pdvet et al (1980) and . However, Panke et al (1978Panke et al ( , 1979Panke et al ( , 1980, Tamarkin et al (1979), Rollag et al (1980) and Brainard et al (1982), determining the concentration of aMT, constantly observed a single peak during the night only. The discrepancy between both data, obtained by two different techniques, might be explained by the fact that a high concentration does not simply mean a high synthesis.…”

Morphometric analysis of the pineal complex of the golden hamster over a 24‐hour light: Dark cycle: I. The superficial pineal in untreated and optically enucleated animals

“…The rhythm in nuclear volume found in this study was similar to the pattern of melatonin production in golden hamsters maintained on a 14:lO 1ight:dark cycle, with peak values toward the end of the scotophase (dark period) (Panke et al, 1980). Our findings of circadian variation in nuclear volume are not, however, in agreement with earlier reports.…”

“…Since protein synthesis increases prior to melatonin production (Morrissey and Lovenberg, 1978), the peak values for the rough endoplasmic reticulum may reflect enhanced protein synthesis during the dark phase, possibly as a result of greater enzyme production. Alternatively, the biphasic rhythm in smooth endoplasmic reticulum is similar to the pattern of indole production by golden hamster pinealocytes, with nadirs occurring at the 1ight:dark interfaces (Panke et al, 1980;Steinlechner et al, 1983). Rhythms in the volume density of the Golgi complex and number of dense-cored vesicles displayed similar patterns.…”

Daily and seasonal rhythmicity in the methylation of pineal indolic compounds in adult male golden hamsters, kept under natural conditions

“…7). Panke et aL (1978Panke et aL ( , 1979Panke et aL ( , 1980, Tamarkin et aL (1979), Rollag et aL (1980), and Brainard et al (1982 b), measuring aMT concentration, found higher concentrations of aMT only during the dark showing a peak at the end of the dark period. This difference might be explained by the use of different experimental approaches (see .…”

Rhythmic synthesis of various 5-methoxyindoles in the pineal gland of male adult golden hamsters, kept under the same artificial conditions throughout the year

“…The same result was obtained in hamsters by Pdvet et al (1980) and . However, Panke et al (1978Panke et al ( , 1979Panke et al ( , 1980, Tamarkin et al (1979), Rollag et al (1980) and Brainard et al (1982), determining the concentration of aMT, constantly observed a single peak during the night only. The discrepancy between both data, obtained by two different techniques, might be explained by the fact that a high concentration does not simply mean a high synthesis.…”

Morphometric analysis of the pineal complex of the golden hamster over a 24‐hour light: Dark cycle: I. The superficial pineal in untreated and optically enucleated animals

“…The rhythm in nuclear volume found in this study was similar to the pattern of melatonin production in golden hamsters maintained on a 14:lO 1ight:dark cycle, with peak values toward the end of the scotophase (dark period) (Panke et al, 1980). Our findings of circadian variation in nuclear volume are not, however, in agreement with earlier reports.…”

“…Since protein synthesis increases prior to melatonin production (Morrissey and Lovenberg, 1978), the peak values for the rough endoplasmic reticulum may reflect enhanced protein synthesis during the dark phase, possibly as a result of greater enzyme production. Alternatively, the biphasic rhythm in smooth endoplasmic reticulum is similar to the pattern of indole production by golden hamster pinealocytes, with nadirs occurring at the 1ight:dark interfaces (Panke et al, 1980;Steinlechner et al, 1983). Rhythms in the volume density of the Golgi complex and number of dense-cored vesicles displayed similar patterns.…”

Daily and seasonal rhythmicity in the methylation of pineal indolic compounds in adult male golden hamsters, kept under natural conditions

“…7). Panke et aL (1978Panke et aL ( , 1979Panke et aL ( , 1980, Tamarkin et aL (1979), Rollag et aL (1980), and Brainard et al (1982 b), measuring aMT concentration, found higher concentrations of aMT only during the dark showing a peak at the end of the dark period. This difference might be explained by the use of different experimental approaches (see .…”

Rhythmic synthesis of various 5-methoxyindoles in the pineal gland of male adult golden hamsters, kept under the same artificial conditions throughout the year

“…The same result was obtained in hamsters by Pdvet et al (1980) and . However, Panke et al (1978Panke et al ( , 1979Panke et al ( , 1980, Tamarkin et al (1979), Rollag et al (1980) and Brainard et al (1982), determining the concentration of aMT, constantly observed a single peak during the night only. The discrepancy between both data, obtained by two different techniques, might be explained by the fact that a high concentration does not simply mean a high synthesis.…”